JP2004359842A

JP2004359842A - Red light-emitting phosphor and light-emitting device

Info

Publication number: JP2004359842A
Application number: JP2003160563A
Authority: JP
Inventors: Tsutomu Odaki; 勉小田喜
Original assignee: Fine Rubber Kenkyusho KK
Current assignee: Fine Rubber Kenkyusho KK
Priority date: 2003-06-05
Filing date: 2003-06-05
Publication date: 2004-12-24
Anticipated expiration: 2023-06-05
Also published as: JP4238980B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a red light-emitting phosphor exhibiting high emission intensity at a wavelength of 400 to 410 nm and to provide a light-emitting device using the same. <P>SOLUTION: The red light-emitting phosphor is represented by the compositional formula: Li<SB>y</SB>A<SB>(1-y)</SB>Eu<SB>x</SB>Sm<SB>(1-x)</SB>W<SB>2</SB>O<SB>8</SB>(1) or Li<SB>z</SB>A<SB>(1-z)</SB>EuW<SB>2</SB>O<SB>8</SB>(2) and emits light when excited with light of a wavelength of 350 to 420 nm. The light-emitting device uses the same. In formulae (1) and (2), A is at least one member selected from the group consisting of Na, K, Rb, and Cs; x is a positive number in the range: 0.8≤x<1; y is a positive number in the range: 0.4≤y≤1; and z is a positive number in the range: 0.7≤z<1. This phosphor has a heretofore unattainably high emission intensity at a wavelength of 400 to 410 nm and can provide a red-light-emitting device, a white- or neutral-color-emitting device when used in conjunction with a green light-emitting phosphor and a blue light-emitting phosphor, and especially a light-emitting device that emits red light or white or neutral-color light at high luminance by using a light-emitting device using an element in which the light emitting wavelength at which the external quantum efficiency is the highest is in the range of 400 to 410 nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、３５０〜４２０ｎｍの長波長紫外線又は短波長可視光線により励起され赤色に発光する赤色発光蛍光体及びその赤色発光蛍光体を用いた発光装置に関する。
【０００２】
【従来の技術】
発光ダイオード（ＬＥＤ：ＬｉｇｈｔＥｍｉｔｔｉｎｇＤｉｏｄｅ）は、光を放射する半導体発光素子であり、電気エネルギーを紫外光、可視光、赤外光などに変換するものである。例えば、可視光を利用するものとしては、ＧａＰ、ＧａＡｓＰ、ＧａＡｌＡｓ等の発光材料で形成した半導体発光素子があり、これらを透明樹脂等で封止したＬＥＤランプが広く使用されている。また、発光材料をプリント基板や金属リードの上面に固定し、数字や文字をかたどった透明樹脂ケースで封止したディスプレイ型のＬＥＤランプなども多用されている。
【０００３】
また、発光ダイオードは半導体素子であるため、寿命が長く、信頼性も高く、光源として用いた場合には、その交換作業も軽減できることから、携帯通信機器、パーソナルコンピュータ周辺機器、ＯＡ機器、家庭用電気機器、オーディオ機器、各種スイッチ、バックライト用光源、掲示板等の各種表示装置などの構成部品として広く使用されている。
【０００４】
このようなＬＥＤランプは、各種の蛍光体粉末を、半導体発光素子を封止する透明樹脂中に含有させることにより、ＬＥＤランプから放射される光の色を変化させることが可能であり、使用用途に応じて青色から赤色まで可視光領域の広い範囲の色を得ることが可能である。
【０００５】
しかしながら、最近では、上記各種表示装置の色彩に対する需要者の要求が高まり、表示装置に微妙な色合いをより精密に再現できる性能が要求されていると共に、１個のＬＥＤランプにより白色や各種の中間色を発光させることができることが強く求められている。
【０００６】
そのため、ＬＥＤランプの半導体発光素子の表面に、赤色、緑色、青色の各種蛍光体を塗布したり、ＬＥＤランプの封止材、コーティング材等に上記各種蛍光体を含有させたりすることにより、１個のＬＥＤランプで白色や各種の中間色を表示できるように構成することも試行されている。
【０００７】
このような蛍光体の中で、長波長紫外線又は短波長可視光線（３５０〜４２０ｎｍ）で励起する蛍光体として、現在、主に使用されているものとしては、発光色が青色のＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ、（Ｓｒ，Ｃａ，Ｂａ）_５（ＰＯ_４）_３Ｃｌ：Ｅｕ、発光色が緑色のＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ，Ｍｎ、Ｚｎ_２ＧｅＯ_４：Ｍｎ、発光色が赤色のＹ_２Ｏ_２Ｓ：Ｅｕ、Ｌａ_２Ｏ_２Ｓ：Ｅｕ、３．５ＭｇＯ・０．５ＭｇＦ_２・ＧｅＯ_２：Ｍｎなどがあり、これらの発光蛍光体を適宜用いることにより広い範囲の発光色を得ることができる。
【０００８】
しかしながら、上記赤色発光蛍光体には、青色、緑色発光蛍光体と比較して長波長紫外線及び短波長可視光線（３５０〜４２０ｎｍ）に対する発光が弱いという問題がある。
【０００９】
そのため、これらの波長の光を用いて白色系の発光色を得る場合、赤色発光蛍光体の割合を多くしなければならず、コストが高くなること、白色系の発光色は、赤色、緑色、青色の発光量のバランスを合わせることにより白色を得ることができるものであるから、白色系の発光色を得るためには、赤色の発光量に合わせて緑色及び青色の発光量を減らさざるを得ず、また、蛍光体の使用量にも上限があるため、得られる白色光の発光量が少なくなってしまい、高輝度の白色が得られないことなどが問題となっている。
【００１０】
また、近年、長波長紫外線及び短波長可視光線領域の光を発光し、高輝度発光を可能とするＬＥＤ素子として注目されているＩｎＧａＮ系素子（非特許文献１参照）は、外部量子効率が最も高い値を示す発光波長が４００ｎｍ前後、特に４００〜４１０ｎｍ程度の波長にあることが報告されており、この範囲の波長において赤色光を高強度で発光できる赤色発光蛍光体が求められている。しかしながら、酸化物系化合物の電子対の励起エネルギーに対応する波長は紫外領域にあり、長波長紫外線及び短波長可視光線（３５０〜４２０ｎｍ）の波長は蛍光体の吸収端と重なるため、これらの赤色発光蛍光体の３５０ｎｍより長波長側での吸収強度は、波長が長くなるに従って急激に低下し、４００ｎｍ以上の範囲ではかなり低くなってしまう。
【００１１】
励起波長を長波長側へシフトさせた赤色発光蛍光体としては、例えば、ユーロピウムで付活された希土類酸硫化物蛍光体が特開平１１−２４６８５７号公報（特許文献１）や特開２０００−１４４１３０号公報（特許文献２）などにおいて提案され、また、本発明者らは、特開２００３−４１２５２号公報（特許文献３）において、ＥｕとＹ，Ｌａ，Ｇｄ及びＬｕからなる群より選ばれた少なくとも１種とを含む金属酸化物系の赤色発光蛍光体について報告しているが、これらの蛍光体の４００ｎｍ以上の励起波長に対する発光強度は十分なものとはなっていなかった。
【００１２】
【特許文献１】
特開平１１−２４６８５７号公報
【特許文献２】
特開２０００−１４４１３０号公報
【特許文献３】
特開２００３−４１２５２号公報
【非特許文献１】
田口常正，「ＬＥＤディスプレイ」，照明学会誌，社団法人照明学会，２００３年，第８７巻，第１号，ｐ．４２−４７
【００１３】
【発明が解決しようとする課題】
本発明は、上記問題点を解決するためになされたものであり、４００〜４１０ｎｍの波長において、高い発光強度を示す赤色発光蛍光体及びこれを用いた発光装置を提供することを目的とする。
【００１４】
【課題を解決するための手段及び発明の実施の形態】
本発明者は、上記問題を解決するため鋭意検討を重ねた結果、波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であって、下記組成式（１）
Ｌｉ_ｙＡ_{（１−ｙ）}Ｅｕ_ｘＳｍ_{（１−ｘ）}Ｗ_２Ｏ_８…（１）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｘは０．８≦ｘ＜１を満たす正数、ｙは０．４≦ｙ≦１を満たす正数である。）
で表わされる赤色発光蛍光体が、４００〜４１０ｎｍの波長において従来にない高い発光強度を示すものであること、更に、上記組成式（１）中のｘが０．９５≦ｘ＜１を満たす正数である赤色発光蛍光体の場合、４００〜４１０ｎｍの波長において従来にない高い発光強度を示すと共に、３５０〜４２０ｎｍの励起光に対して従来の蛍光体と同等又はそれ以上の発光強度を示すものであり、長波長紫外線から短波長可視光線の領域の広い範囲の波長に対して安定して高い強度で赤色を発光できるものであることを見出した。
【００１５】
また、波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であって、下記組成式（２）
Ｌｉ_ｚＡ_{（１−ｚ）}ＥｕＷ_２Ｏ_８…（２）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｚは０．７≦ｚ＜１を満たす正数である。）
で表わされる赤色発光蛍光体が、４００〜４１０ｎｍの波長において従来にない高い発光強度を示すと共に、３５０〜４２０ｎｍの励起光に対して従来の蛍光体より高い発光強度を示すものであり、長波長紫外線から短波長可視光線の領域の広い範囲の波長に対して安定して高い強度で赤色を発光できるものであることを見出した。
【００１６】
更に、これらの赤色発光蛍光体を用いた赤色を表示する発光装置又は緑色発光蛍光体、青色発光蛍光体と併用して白色若しくは中間色を表示する発光装置は高輝度で発光する発光装置となり、特に、ＩｎＧａＮ系素子等の外部量子効率が最も高い値を示す発光波長が４００〜４１０ｎｍ、特に４０５ｎｍ前後にある素子を用いた発光装置として有効であること、更に、上記組成式（１）で示され、式中のｘが０．９５≦ｘ＜１を満たす正数である赤色発光蛍光体又は上記組成式（２）で示される赤色発光蛍光体を用いた場合、励起波長が３５０〜４２０ｎｍの広い範囲において高い発光強度を示すため、発光素子の個体差による励起光の波長の変動の影響を受けにくく、例えば、緑色発光蛍光体、青色発光蛍光体と併用して上記波長の光を発光する半導体発光素子からの光により蛍光体を発光させて白色若しくは中間色を表示する場合、微妙な色合いをより精密に再現性よく、また高輝度で表示することができることを見出し、本発明をなすに至った。
【００１７】
即ち、本発明は、
［１］波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であって、下記組成式（１）
Ｌｉ_ｙＡ_{（１−ｙ）}Ｅｕ_ｘＳｍ_{（１−ｘ）}Ｗ_２Ｏ_８…（１）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｘは０．８≦ｘ＜１を満たす正数、ｙは０．４≦ｙ≦１を満たす正数である。）
で表わされるものであることを特徴とする赤色発光蛍光体、
［２］上記組成式（１）中のｘが０．９５≦ｘ＜１を満たす正数であることを特徴とする［１］記載の赤色発光蛍光体、
［３］波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であって、下記組成式（２）
Ｌｉ_ｚＡ_{（１−ｚ）}ＥｕＷ_２Ｏ_８…（２）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｚは０．７≦ｚ＜１を満たす正数である。）
で表わされるものであることを特徴とする赤色発光蛍光体、
［４］波長が３５０〜４２０ｎｍの光を発光する半導体発光素子が封止材内に封止されてなる発光装置であって、上記封止材に［１］乃至［３］のいずれかに記載の赤色発光蛍光体を分散させたことを特徴とする発光装置、
［５］波長が３５０〜４２０ｎｍの光を発光する半導体発光素子が封止材内に封止されてなる発光装置であって、上記半導体発光素子から発光する光の光路上に［１］乃至［３］のいずれかに記載の赤色発光蛍光体を含む蛍光層を設けたことを特徴とする発光装置、
［６］上記半導体発光素子上又は封止材上に蛍光層を設けたことを特徴とする［５］記載の発光装置、及び
［７］上記蛍光層が上記赤色発光蛍光体を樹脂、ゴム、エラストマー又はガラスに分散してなるものであることを特徴とする［６］記載の発光装置
を提供する。
【００１８】
以下、本発明について更に詳述する。
まず、本発明の赤色発光蛍光体の第１の態様について説明する。この第１の態様の赤色発光蛍光体は、波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であり、下記組成式（１）
Ｌｉ_ｙＡ_{（１−ｙ）}Ｅｕ_ｘＳｍ_{（１−ｘ）}Ｗ_２Ｏ_８…（１）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｘは０．８≦ｘ＜１を満たす正数、ｙは０．４≦ｙ≦１を満たす正数である。）
で表わされるものである。
【００１９】
本発明の第１の態様の赤色発光蛍光体において、上記組成式（１）で表される赤色発光蛍光体は、式中のｙが０．４≦ｙ≦１を満たす範囲となるように、Ｌｉと共に、Ａで示されるＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種のアルカリ金属、好ましくはＮａ及びＫからなる群より選ばれる少なくとも１種のアルカリ金属、特に好ましくはＮａを含有するものである。即ち、本発明の赤色発光蛍光体は、アルカリ金属として、Ｌｉのみを含有するもの（ｙ＝１の場合）、並びにＬｉを含み、更に、Ａで示されるＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種のアルカリ金属、好ましくはＮａ及びＫからなる群より選ばれる少なくとも１種のアルカリ金属、特に好ましくはＮａを含有するもの（０．４≦ｙ＜１の場合）である。なお、上記組成式（１）中のｙは０．４≦ｙ≦１を満たす範囲であるが、このｙの範囲（下限）は０．６以上、特に０．７以上であることが好ましく、またｙの範囲（上限）は１未満、特に０．９以下であることが好ましい。
【００２０】
また、本発明の第１の態様の赤色発光蛍光体は、Ｅｕ（ユウロピウム）と共にＳｍ（サマリウム）を含むものであり、上記組成式（１）で表されるものであるが、このようなものとしては、例えば、下記組成式（３）、
ＬｉＥｕＷ_２Ｏ_８…（３）
で表される金属酸化物の結晶中のＥｕ（Ｅｕイオン）サイトの一部がＳｍ（Ｓｍイオン）で置換された構造のもの、また、上記組成式（１）中のＡで示されるアルカリ金属を含有する場合（０．４≦ｙ＜１の場合）は、更に結晶中のＬｉ（Ｌｉイオン）サイトの一部がＡで示されるアルカリ金属（Ａで示されるアルカリ金属のイオン）で置換された構造のものが挙げられる。結晶中にＥｕとＳｍとを共存させることにより、４００〜４１０ｎｍ、特に４０５ｎｍ前後の励起光で高強度の赤色発光を示す赤色発光蛍光体となり、更に結晶中にＬｉとＮａとを共存させることにより、特に高強度の赤色発光を示す赤色発光蛍光体となる。
【００２１】
更に、ＥｕとＳｍとの比は上記組成式（１）中のｘが０．８≦ｘ＜１、好ましくは０．９≦ｘ＜１を満たす正数（ＥｕイオンからＳｍイオンへの置換率Ｒが０＜Ｒ≦２０ａｔ％、好ましくは０＜Ｒ≦１０ａｔ％）となる比率である。ｘの値が０．８未満の場合（置換率Ｒが２０％を超える場合）は、上記した４００〜４１０ｎｍ、特に４０５ｎｍ前後の励起光による十分な赤色発光が得られない。
【００２２】
本発明の第１の態様の赤色発光蛍光体においては、更に、上記組成式（１）中のｘが０．９５≦ｘ＜１、特に０．９６≦ｘ＜１、とりわけ０．９６≦ｘ≦０．９８を満たす正数（ＥｕイオンからＳｍイオンへの置換率Ｒが０＜Ｒ≦５ａｔ％、特に０＜Ｒ≦４ａｔ％、とりわけ２≦Ｒ≦４ａｔ％）であることが好ましい。ｘ（置換率Ｒ）がこの範囲を満たす場合、この赤色発光蛍光体は、４００〜４１０ｎｍ、特に４０５ｎｍ前後の励起光により、特に高強度の赤色発光を示す赤色発光蛍光体となる上に、３５０〜４２０ｎｍの範囲の励起光に対して（即ち、４００〜４１０ｎｍよりも広い範囲の励起光に対しても）従来の蛍光体と同等又はそれ以上の発光強度を示すものとなり、励起波長が３５０〜４２０ｎｍの広い範囲において高い発光強度を示す極めて優れた赤色発光蛍光体となるため好ましい。
【００２３】
次に、本発明の赤色発光蛍光体の第２の態様について説明する。この第２の態様の赤色発光蛍光体は、波長が３５０〜４２０ｎｍの光により励起されて発光する赤色発光蛍光体であり、下記組成式（２）
Ｌｉ_ｚＡ_{（１−ｚ）}ＥｕＷ_２Ｏ_８…（２）
（式中、ＡはＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種であり、ｚは０．７≦ｚ＜１を満たす正数である。）
で表わされるものである。
【００２４】
本発明の第２の態様の赤色発光蛍光体において、上記組成式（２）で表される赤色発光蛍光体は、式中のｚが０．７≦ｚ＜１を満たす範囲となるように、Ｌｉと共に、Ａで示されるＮａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種のアルカリ金属、好ましくはＮａ及びＫからなる群より選ばれる少なくとも１種のアルカリ金属、特に好ましくはＮａを含有するものである。なお、上記組成式（２）中のｚは０．７≦ｚ＜１を満たす範囲であるが、このｚの範囲（下限）は０．８以上であることが好ましく、またｚの範囲（上限）は０．９９以下、特に０．９５以下であることが好ましい。
【００２５】
また、本発明の第２の態様の赤色発光蛍光体は、アルカリ金属としてＬｉと共に上記組成式（２）中のＡで示されるアルカリ金属を含むものであり、上記組成式（２）で表されるものであるが、このようなものとしては、例えば、下記組成式（３）、
ＬｉＥｕＷ_２Ｏ_８…（３）
で表される金属酸化物の結晶中のＬｉ（Ｌｉイオン）サイトの一部がＡで示されるアルカリ金属（Ａで示されるアルカリ金属のイオン）で置換された構造のものが挙げられる。結晶中にＬｉとＮａとを共存させることにより、４００〜４１０ｎｍ、特に４０５ｎｍ前後の励起光で高強度の赤色発光を示す赤色発光蛍光体となる。
【００２６】
本発明において、赤色発光蛍光体は、原料として、赤色発光蛍光体を構成する元素を含む酸化物、炭酸塩など、例えば、Ｌｉ_２ＣＯ_３、Ｎａ_２ＣＯ_３、Ｅｕ_２Ｏ_３、Ｓｍ_２Ｏ_３、Ｗ_２Ｏ_３等を、焼成後に上記組成式（１）又は組成式（２）で示される所定の組成となるように化学量論比で配合し、ボールミル等で混合して得た原料混合物を焼成し、必要に応じて水洗、粉砕、篩分けして得ることができる。
【００２７】
焼成の方法は、蛍光体として用いられる金属酸化物の製造に用いられる従来公知の方法を適用することが可能であり、特に限定されないが、例えばアルミナ製坩堝中に上記原料混合物を入れて、電気炉等の焼成炉で焼成して製造する方法が採用し得る。この場合、焼成温度は８００〜１，０００℃、特に８５０〜９００℃であることが好ましく、また、焼成時間は３０分〜４８時間、特に２〜１２時間であることが好ましい。
【００２８】
更に、本発明においては、上記組成式（１）又は組成式（２）で表わされる赤色発光蛍光体の、式中のアルカリ金属元素、即ち、Ｌｉ及び／又はＡ（Ｎａ，Ｋ，Ｒｂ及びＣｓからなる群より選ばれる少なくとも１種）の一部が、共付活剤として添加されるＭｇ、Ｃａ、Ｓｒ及びＢａからなる群より選ばれる少なくとも１種で置換されたものも好適である。この場合の置換率は、Ｌｉ及びＡ（Ｎａ，Ｋ，Ｒｂ及びＣｓ）の総量に対するＭｇ、Ｃａ、Ｓｒ及びＢａの総量の比で０．５（原子比）未満、好ましくは０．３（原子比）以下、更に好ましくは０．２（原子比）以下、特に好ましくは０．１（原子比）以下であることが好ましい。また、この場合、置換率の下限は特に限定されるものではないが、好ましくは０．０１（原子比）以上、更に好ましくは０．０５（原子比）以上である。
【００２９】
次に、本発明の発光装置について説明する。
まず、本発明の発光装置の第１の態様について説明する。この第１の態様の発光装置は、波長が３５０〜４２０ｎｍの光を発光する半導体発光素子が封止材内に封止されてなる発光装置であって、上記封止材に上述した本発明の赤色発光蛍光体を分散させたものである。
【００３０】
具体的には、図１に示されるような、リード１，２、波長が３５０〜４２０ｎｍの光を発光する半導体発光素子３、半導体発光素子３とリード２とを電気的に接続するリード細線４を、封止材５で砲弾型に封止した構造の、いわゆる砲弾タイプの発光ダイオードや、図２に示されるような、上面が開口した箱形の発光体収容部材６の内底から一対のリード１，２を発光体収容部材６の外部へ延出し、この発光体収容部材６の内部に波長が３５０〜４２０ｎｍの光を発光する半導体発光素子３やリード細線４，４を収容し、これらを接続して発光体収容部材６内部を封止材５で封止した構造の、いわゆるチップ型の発光ダイオードなどの封止材５中に、本発明の赤色発光蛍光体を分散させたものが挙げられる。
【００３１】
この場合、封止材５中に上述した本発明の赤色発光蛍光体のみを分散させれば、高輝度の赤色を発光する発光装置となり、ＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ，Ｍｎ、Ｚｎ_２ＧｅＯ_４：Ｍｎ等の緑色発光蛍光体、ＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ、（Ｓｒ，Ｃａ，Ｂａ）_５（ＰＯ_４）_３Ｃｌ：Ｅｕ等の青色蛍光発光体と共に分散させれば、高輝度の白色又は中間色を発光する発光装置となる。これらいずれの発光装置においても、赤色発光蛍光体として本発明の赤色発光蛍光体以外の赤色発光蛍光体、例えば、Ｙ_２Ｏ_２Ｓ：Ｅｕ、Ｌａ_２Ｏ_２Ｓ：Ｅｕ、３．５ＭｇＯ・０．５ＭｇＦ_２・ＧｅＯ_２：Ｍｎ等を添加することが可能である。
【００３２】
なお、この発光装置は、半導体発光素子等を封止する際に、樹脂、ゴム、エラストマー、ガラスなどの封止材材料に蛍光体を混合して封止することにより製造することができる。特に、複数種の蛍光体を用いる場合、本発明の赤色発光蛍光体は、一般的な蛍光体に比べ、真比重が高いため封止材料と混合したときに他の蛍光体よりも速く沈降して色むらを引き起こすおそれがある。そのため、本発明の赤色発光蛍光体は、粘度の高いもの、例えば、チキソトロピー調整剤で粘度を調整したシリコーンゴム組成物、シリコーン樹脂組成物などに混合し、これを硬化させる方法で封止材中に分散させることが好ましい。また、封止材中には色調変換材料として上述した蛍光体の他に、顔料、染料、擬似顔料などを添加してもよい。
【００３３】
次に、本発明の発光装置の第２の態様について説明する。この第２の態様の発光装置は、波長が３５０〜４２０ｎｍの光を発光する半導体発光素子が封止材内に封止されてなる発光装置であって、上記半導体発光素子から発光する光の光路上に上述した本発明の赤色発光蛍光体を含む蛍光層を設けたものである。
【００３４】
このようなものとしては、例えば、半導体発光素子上又は封止材上に本発明の赤色発光蛍光体を含む蛍光層を設けたものが挙げられ、具体的には、図３に示されるような、リード１，２、波長が３５０〜４２０ｎｍの光を発光する半導体発光素子３、半導体発光素子３とリード２とを電気的に接続するリード細線４を、封止材５で砲弾型に封止した構造の、いわゆる砲弾タイプの発光ダイオードの半導体発光素子３上に蛍光層７を設けて半導体発光素子３等と共に封止したもの、図４に示されるような上面が開口した箱形の発光体収容部材６の内底から一対のリード１，２を発光体収容部材６の外部へ延出し、この発光体収容部材６の内部に波長が３５０〜４２０ｎｍの光を発光する半導体発光素子３やリード細線４，４を収容し、これらを接続して、発光体収容部材６内部を封止材５で封止した構造の、いわゆるチップ型の発光ダイオードの半導体発光素子３上に蛍光層７を設けて半導体発光素子３等と共に封止したもの、図５に示されるような砲弾タイプの発光ダイオードの封止材５上に封止材５を被覆するように蛍光層７を設けたもの、図６に示されるようなチップ型の発光ダイオードの封止材５上に蛍光層７を設けたものが挙げられる。なお、図５、図６中の蛍光層以外の構成は図１、図２に各々示される構成と同様であるため説明を省略する。
【００３５】
また、上述したような、蛍光層を発光ダイオード内部に又は発光ダイオードと隣接して設けたいわゆる透過型のものに限らず、図７に示されるように、蛍光層７を発光ダイオード８から離間する位置に設けると共に、この蛍光層から発光した光を反射板９で反射させるいわゆる反射型の発光装置も挙げられる。また、図５、図６に示されるような封止材上に蛍光層を設けた発光装置の蛍光層を、更に封止材で封止することも可能である。
【００３６】
この場合、蛍光層中に上述した本発明の赤色発光蛍光体のみを分散させれば、高輝度の赤色を発光する発光装置となり、ＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ，Ｍｎ、Ｚｎ_２ＧｅＯ_４：Ｍｎ等の緑色発光蛍光体、ＢａＭｇ_２Ａｌ_１６Ｏ_２７：Ｅｕ、（Ｓｒ，Ｃａ，Ｂａ）_５（ＰＯ_４）_３Ｃｌ：Ｅｕ等の青色蛍光発光体と共に分散させれば、高輝度の白色又は中間色を発光する発光装置となる。これらいずれの発光装置においても、赤色発光蛍光体として本発明の赤色発光蛍光体以外の赤色発光蛍光体、例えば、Ｙ_２Ｏ_２Ｓ：Ｅｕ、Ｌａ_２Ｏ_２Ｓ：Ｅｕ、３．５ＭｇＯ・０．５ＭｇＦ_２・ＧｅＯ_２：Ｍｎ等を添加することが可能である。
【００３７】
なお、蛍光層を半導体発光素子上に設ける場合は、蛍光体をそのままで用いてもバインダーと共に混合して用いてもよい。この場合、図３、図４に示されるように、蛍光層は半導体発光素子と共に封止材中に封止されることとなる。
【００３８】
一方、蛍光層を封止材上に設ける場合、赤色発光蛍光体を透光性の樹脂、ゴム、エラストマー又はガラス、特にシリコーン樹脂又はシリコーンゴムに分散させて用いることが好ましい。特に、複数種の蛍光体を蛍光層に分散させる場合、上述した封止材に本発明の赤色発光蛍光体を分散させる場合と同様、チキソトロピー調整剤で粘度を調整したシリコーンゴム組成物、シリコーン樹脂組成物などに混合し、これを硬化させる方法で蛍光層中に分散させることが好ましい。また、蛍光層は、蛍光体を混合して１層としたものでも、蛍光体をいくつかの層にわけて積層したものでもよい。また、蛍光層中には色調変換材料として上述した蛍光体の他に、顔料、染料、擬似顔料などを添加してもよい。
【００３９】
本発明の発光装置は、赤色発光蛍光体として上記組成式（１）又は上記組成式（２）で示される赤色発光蛍光体を用いているため、ＩｎＧａＮ系素子等の外部量子効率が最も高い値を示す発光波長が４００〜４１０ｎｍ、特に４０５ｎｍ前後にある素子を用いた発光装置として好適である。特に、上記組成式（１）で示され、式中のｘが０．９５≦ｘ＜１を満たす正数である赤色発光蛍光体又は上記組成式（２）で示される赤色発光蛍光体を用いた発光装置は、励起波長が３５０〜４２０ｎｍの広い範囲において高い発光強度を示すため、発光素子の個体差による励起光の波長の変動の影響を受けにくく、例えば、緑色発光蛍光体、青色発光蛍光体と併用して上記波長の光を発光する半導体発光素子からの光により蛍光体を発光させて白色若しくは中間色を表示する場合、微妙な色合いをより精密に再現性よく、また高輝度で表示することができることから好ましい。
【００４０】
【実施例】
以下、実施例及び比較例を挙げて本発明を具体的に説明するが、本発明は下記実施例に限定されるものではない。
【００４１】
［実施例１］
蛍光体構成原料として、表１に示すように、ＷＯ_３粉末を７．８１１２ｇ、Ｅｕ_２Ｏ_３粉末を２．９３４６ｇ、Ｓｍ_２Ｏ_３粉末を０．０２９４ｇ、Ｌｉ_２ＣＯ_３粉末を０．６２２４ｇ各々秤量し、これらをボールミルで均一に混合して原料混合物とした。
【００４２】
次に、得られた原料混合物を、アルミナ製坩堝に入れ９００℃の温度で６時間焼成した。得られた焼成物を純水にて十分洗浄して不要な可溶成分を除去し、その後、ボールミルにより細かく粉砕し、篩分け（目開き５３μｍ）してＬｉＥｕ_０．９９Ｓｍ_０．０１Ｗ_２Ｏ_８で示される組成の赤色発光蛍光体を得た。
【００４３】
この赤色発光蛍光体について、３８０ｎｍ、３９５ｎｍ及び４０５ｎｍ励起下において小型分光蛍光光度計ＦＰ−７５０（日本分光（株）製）で各々の励起波長における発光強度を測定した。結果を表１及び図８に示す。
【００４４】
［実施例２〜６］
Ｅｕ_２Ｏ_３粉末及びＳｍ_２Ｏ_３粉末の量を表１に示すようにした以外は、実施例１と同様の方法で赤色発光蛍光体（ＬｉＥｕ_０．９８Ｓｍ_０．０２Ｗ_２Ｏ_８（実施例２）、ＬｉＥｕ_０．９７Ｓｍ_０．０３Ｗ_２Ｏ_８（実施例３）、ＬｉＥｕ_０．９６Ｓｍ_０．０４Ｗ_２Ｏ_８（実施例４）、ＬｉＥｕ_０．９５Ｓｍ_０．０５Ｗ_２Ｏ_８（実施例５）、ＬｉＥｕ_０．９０Ｓｍ_０．１０Ｗ_２Ｏ_８（実施例６））を得、実施例１と同様に発光強度を測定した。結果を表１及び図８に示す。また、実施例３で得られた赤色発光蛍光体の励起スペクトルを図９に、実施例６で得られた赤色発光蛍光体のＸ線回折パターンを図１０に示す。
【００４５】
［実施例７］
蛍光体構成原料として、表１に示すように、ＷＯ_３粉末を７．８１１２ｇ、Ｅｕ_２Ｏ_３粉末を２．８４５６ｇ、Ｓｍ_２Ｏ_３粉末を０．１１７５ｇ、Ｎａ_２ＣＯ_３粉末を０．２６７９ｇ、Ｌｉ_２ＣＯ_３粉末を０．４３５７ｇ各々秤量し、これらをボールミルで均一に混合して原料混合物とした。
【００４６】
次に、得られた原料混合物を、アルミナ製坩堝に入れ９００℃の温度で６時間焼成した。得られた焼成物を純水にて十分洗浄して不要な可溶成分を除去し、その後、ボールミルにより細かく粉砕し、篩分け（目開き５３μｍ）してＬｉ_０．７Ｎａ_０．３Ｅｕ_０．９６Ｓｍ_０．０４Ｗ_２Ｏ_８で示される組成の赤色発光蛍光体を得た。
【００４７】
この赤色発光蛍光体について、３８０ｎｍ、３９５ｎｍ及び４０５ｎｍ励起下において小型分光蛍光光度計ＦＰ−７５０（日本分光（株）製）で各々の励起波長における発光強度を測定した。結果を表１に示す。
【００４８】
［比較例１］
Ｅｕ_２Ｏ_３粉末の量を表１に示すようにし、Ｓｍ_２Ｏ_３粉末を配合しなかった以外は、実施例１と同様の方法でＬｉＥｕＷ_２Ｏ_８で示される組成の赤色発光蛍光体を得、実施例１と同様に発光強度を測定した。結果を表１及び図８に示す。また、この赤色発光蛍光体の励起スペクトルを図９に、Ｘ線回折パターンを図１０に示す。
【００４９】
【表１】

【００５０】
表１及び図８，９から本発明の第１の態様の赤色発光蛍光体の一例である実施例１〜７の赤色発光蛍光体が４０５ｎｍの波長において従来にない高い発光強度を示すものであることがわかる。また、上記組成式（１）中のｘが０．９５≦ｘ＜１の範囲にある実施例１〜５及び実施例７は３５０〜４２０ｎｍの広い範囲の波長において、比較例１で示す従来のものと同等又はそれ以上の発光強度を示すものであり、特に、上記組成式（１）中のＡとしてＮａを含有し、ｙが０．７である実施例７は３５０〜４２０ｎｍの広い範囲の波長において、比較例１で示す従来のものをはるかに超える高い発光強度を示すものであることがわかる。
【００５１】
更に、図１０に示されるように、Ｓｍを最も多く含有する実施例６の赤色発光蛍光体のＸ線回折パターンがＬｉＥｕＷ_２Ｏ_８と同様のＸ線回折パターンを示すこと（Ｓｍに由来するピークが出現していないこと）から、本発明の赤色発光蛍光体が、下記式（４）
ＬｉＥｕＷ_２Ｏ_８…（４）
で表されるＥｕを含む金属酸化物の結晶中のＥｕ（Ｅｕイオン）サイトの一部がＳｍ（Ｓｍイオン）に置換された構造を有しているものであることが支持される。
【００５２】
［実施例８］
蛍光体構成原料として、表２に示すように、ＷＯ_３粉末を７．８１１２ｇ、Ｅｕ_２Ｏ_３粉末を２．９６４２ｇ、Ｎａ_２ＣＯ_３粉末を０．１７８６ｇ、Ｌｉ_２ＣＯ_３粉末を０．４９７９ｇ各々秤量し、これらをボールミルで均一に混合して原料混合物とした。
【００５３】
次に、得られた原料混合物を、アルミナ製坩堝に入れ９００℃の温度で６時間焼成した。得られた焼成物を純水にて十分洗浄して不要な可溶成分を除去し、その後、ボールミルにより細かく粉砕し、篩分け（目開き５３μｍ）してＬｉ_０．８Ｎａ_０．２ＥｕＷ_２Ｏ_８で示される組成の赤色発光蛍光体を得た。
【００５４】
この赤色発光蛍光体について、３８０ｎｍ、３９５ｎｍ及び４０５ｎｍ励起下において小型分光蛍光光度計ＦＰ−７５０（日本分光（株）製）で各々の励起波長における発光強度を測定した。結果を表２に比較例１の結果と共に示す。また、得られた赤色発光蛍光体の励起スペクトルを図１１に比較例１のスペクトルと共に示す。
【００５５】
【表２】

【００５６】
表２及び図１１から本発明の第２の態様の赤色発光蛍光体の一例である実施例８の赤色発光蛍光体が４０５ｎｍの波長において従来にない高い発光強度を示すと共に、３５０〜４２０ｎｍの広い範囲の波長において、比較例１で示す従来のものより高い発光強度を示すものであることがわかる。
【００５７】
【発明の効果】
以上のように、本発明の赤色発光蛍光体は、４００〜４１０ｎｍ、特に４０５ｎｍ前後の波長において従来にない高い発光強度を示すものであり、赤色を表示する発光装置又は緑色発光蛍光体、青色発光蛍光体と併用して白色若しくは中間色を表示する発光装置、特に、ＩｎＧａＮ系素子等の外部量子効率が最も高い値を示す発光波長が４００〜４１０ｎｍ、特に４０５ｎｍ前後にある素子を用いた発光装置に用いることにより高輝度で赤色又は白色若しくは中間色を発光する発光装置が得られる。
【図面の簡単な説明】
【図１】本発明の光学装置の一例を示す図であり、砲弾型の発光ダイオードの封止材に本発明の赤色発光蛍光体を分散させた発光装置を示す断面図である。
【図２】本発明の光学装置の一例を示す図であり、チップ型の発光ダイオードの封止材に本発明の赤色発光蛍光体を分散させた発光装置を示す断面図である。
【図３】本発明の光学装置の一例を示す図であり、砲弾型の発光ダイオードの半導体発光素子上に本発明の赤色発光蛍光体を含む蛍光層を設けた発光装置を示す断面図である。
【図４】本発明の光学装置の一例を示す図であり、チップ型の発光ダイオードの半導体発光素子上に本発明の赤色発光蛍光体を含む蛍光層を設けた発光装置を示す断面図である。
【図５】本発明の光学装置の一例を示す図であり、砲弾型の発光ダイオードの封止材上に本発明の赤色発光蛍光体を含む蛍光層を設けた発光装置を示す断面図である。
【図６】本発明の光学装置の一例を示す図であり、チップ型の発光ダイオードの封止材上に本発明の赤色発光蛍光体を含む蛍光層を設けた発光装置を示す断面図である。
【図７】本発明の光学装置の一例を示す図であり、蛍光層を発光ダイオードから離間する位置に設けると共に、この蛍光層から発光した光を反射させる発光装置を示す断面図である。
【図８】実施例１〜６及び比較例１の赤色発光蛍光体の３８０ｎｍ、３９５ｎｍ及び４０５ｎｍの励起光による発光強度をＳｍの置換率に対してプロットしたグラフである。
【図９】実施例３及び比較例１の赤色発光蛍光体の励起スペクトルである。
【図１０】実施例６及び比較例１の赤色発光蛍光体のＸ線回折パターンである。
【図１１】実施例８及び比較例１の赤色発光蛍光体の励起スペクトルである。
【符号の説明】
１，２リード
３半導体発光素子
４リード細線
５封止材
６発光体収容部材
７蛍光層
８発光ダイオード
９反射板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a red light-emitting phosphor that emits red light when excited by long-wavelength ultraviolet light or short-wavelength visible light of 350 to 420 nm, and a light-emitting device using the red light-emitting phosphor.
[0002]
[Prior art]
A light emitting diode (LED: Light Emitting Diode) is a semiconductor light emitting element that emits light, and converts electrical energy into ultraviolet light, visible light, infrared light, and the like. For example, as a device using visible light, there is a semiconductor light emitting element formed of a light emitting material such as GaP, GaAsP, or GaAlAs, and an LED lamp in which these are sealed with a transparent resin or the like is widely used. In addition, a display-type LED lamp in which a light emitting material is fixed on the upper surface of a printed circuit board or a metal lead and sealed with a transparent resin case shaped like a number or letter is also frequently used.
[0003]
In addition, since the light emitting diode is a semiconductor element, it has a long life, high reliability, and when used as a light source, the replacement work can be reduced. Therefore, portable communication devices, personal computer peripheral devices, OA devices, home use It is widely used as a component of various display devices such as electric devices, audio devices, various switches, backlight light sources, and bulletin boards.
[0004]
Such an LED lamp can change the color of light emitted from the LED lamp by including various phosphor powders in a transparent resin that seals the semiconductor light emitting device. Accordingly, it is possible to obtain a wide range of colors in the visible light region from blue to red.
[0005]
However, recently, demands from consumers for the colors of the various display devices have been increased, and the display device has been required to have a performance capable of reproducing subtle hues more precisely, and white and various intermediate colors can be obtained by a single LED lamp. There is a strong demand to be able to emit light.
[0006]
Therefore, by applying various phosphors of red, green, and blue to the surface of the semiconductor light emitting element of the LED lamp, or by incorporating the various phosphors into the sealing material, coating material, etc. of the LED lamp, 1 Attempts have also been made to configure white LED and various intermediate colors with a single LED lamp.
[0007]
Among such phosphors, currently used as a phosphor that is excited by long-wavelength ultraviolet light or short-wavelength visible light (350 to 420 nm), the light emission color is BaMg. ₂ Al ₁₆ O ₂₇ : Eu, (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ Cl: Eu, green color of BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn, Zn ₂ GeO ₄ : Mn, Y whose emission color is red ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, 3.5MgO / 0.5MgF ₂ ・ GeO ₂ : Mn and the like, and a wide range of emission colors can be obtained by appropriately using these light emitting phosphors.
[0008]
However, the red light-emitting phosphor has a problem that light emission with respect to long-wavelength ultraviolet light and short-wavelength visible light (350 to 420 nm) is weaker than blue and green light-emitting phosphors.
[0009]
Therefore, when obtaining a white emission color using light of these wavelengths, the proportion of the red light emitting phosphor must be increased, the cost is increased, and the white emission color is red, green, Since white can be obtained by adjusting the balance of the blue light emission amount, in order to obtain a white light emission color, the green and blue light emission amounts must be reduced in accordance with the red light emission amount. In addition, since there is an upper limit to the amount of phosphor used, there is a problem in that the amount of white light obtained is reduced, and high brightness white cannot be obtained.
[0010]
In recent years, InGaN-based devices (see Non-Patent Document 1), which are attracting attention as LED devices that emit light in the long-wavelength ultraviolet and short-wavelength visible light regions and enable high-intensity light emission, have the highest external quantum efficiency. It has been reported that an emission wavelength exhibiting a high value is around 400 nm, particularly about 400 to 410 nm, and a red light emitting phosphor capable of emitting red light with high intensity at a wavelength in this range is desired. However, the wavelength corresponding to the excitation energy of the electron pair of the oxide compound is in the ultraviolet region, and the wavelengths of long-wavelength ultraviolet light and short-wavelength visible light (350 to 420 nm) overlap with the absorption edge of the phosphor. The absorption intensity of the light emitting phosphor on the longer wavelength side than 350 nm rapidly decreases as the wavelength becomes longer, and becomes considerably low in the range of 400 nm or more.
[0011]
As red light emitting phosphors whose excitation wavelength is shifted to the longer wavelength side, for example, rare earth oxysulfide phosphors activated with europium are disclosed in JP-A-11-246857 (Patent Document 1) and JP-A-2000-144130. The present inventors have been selected from the group consisting of Eu, Y, La, Gd and Lu in Japanese Patent Application Laid-Open No. 2003-41252 (Patent Document 3). Although metal oxide-based red light-emitting phosphors containing at least one kind have been reported, the emission intensity of these phosphors with respect to excitation wavelengths of 400 nm or more has not been sufficient.
[0012]
[Patent Document 1]
JP 11-246857 A
[Patent Document 2]
JP 2000-144130 A
[Patent Document 3]
JP 2003-41252 A
[Non-Patent Document 1]
Taguchi Tsunemasa, "LED Display", Journal of the Illuminating Society of Japan, Illuminating Institute of Japan, 2003, Vol. 87, No. 1, p. 42-47
[0013]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a red light emitting phosphor exhibiting a high light emission intensity at a wavelength of 400 to 410 nm and a light emitting device using the red light emitting phosphor.
[0014]
Means for Solving the Problem and Embodiment of the Invention
As a result of intensive studies to solve the above problems, the present inventor is a red light emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (1)
Li _y A _(1-y) Eu _x Sm _(1-x) W ₂ O ₈ ... (1)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, x is a positive number satisfying 0.8 ≦ x <1, and y satisfies 0.4 ≦ y ≦ 1. (It is a positive number.)
The red light-emitting phosphor represented by the formula (1) exhibits an unprecedented high emission intensity at a wavelength of 400 to 410 nm, and x in the composition formula (1) is a positive value satisfying 0.95 ≦ x <1. In the case of a red light emitting phosphor, which is a number, it exhibits an unprecedented high emission intensity at a wavelength of 400 to 410 nm, and an emission intensity equal to or higher than that of a conventional phosphor for excitation light of 350 to 420 nm The present inventors have found that red light can be emitted stably and with high intensity with respect to a wide range of wavelengths ranging from long-wavelength ultraviolet light to short-wavelength visible light.
[0015]
Further, it is a red light emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (2)
Li _z A _(1-z) EuW ₂ O ₈ ... (2)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, and z is a positive number satisfying 0.7 ≦ z <1.)
The red light-emitting phosphor represented by the formula has a higher emission intensity than the conventional phosphor at a wavelength of 400 to 410 nm, and a higher emission intensity than the conventional phosphor with respect to the excitation light of 350 to 420 nm, and has a long wavelength. It has been found that red light can be emitted stably and with high intensity over a wide range of wavelengths from ultraviolet to short-wavelength visible light.
[0016]
Further, a light emitting device that displays red using these red light emitting phosphors, or a light emitting device that displays white or an intermediate color in combination with a green light emitting phosphor or a blue light emitting phosphor is a light emitting device that emits light with high brightness. It is effective as a light-emitting device using an element having an emission wavelength having the highest external quantum efficiency such as an InGaN-based element of 400 to 410 nm, particularly around 405 nm, and is further represented by the above composition formula (1). When the red light emitting phosphor in which x in the formula is a positive number satisfying 0.95 ≦ x <1 or the red light emitting phosphor represented by the composition formula (2) is used, the excitation wavelength is wide at 350 to 420 nm. Since it shows high emission intensity in the range, it is not easily affected by fluctuations in the wavelength of the excitation light due to individual differences of the light emitting elements.For example, it emits light with the above wavelengths in combination with green light emitting phosphors and blue light emitting phosphors. In the case of displaying a white or intermediate color by emitting a phosphor with light from a semiconductor light emitting device, it has been found that subtle hues can be displayed more precisely with high reproducibility and with high brightness. It came.
[0017]
That is, the present invention
[1] A red light-emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (1)
Li _y A _(1-y) Eu _x Sm _(1-x) W ₂ O ₈ ... (1)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, x is a positive number satisfying 0.8 ≦ x <1, and y satisfies 0.4 ≦ y ≦ 1. (It is a positive number.)
A red light-emitting phosphor, characterized in that
[2] The red-emitting phosphor according to [1], wherein x in the composition formula (1) is a positive number satisfying 0.95 ≦ x <1;
[3] A red light-emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (2)
Li _z A _(1-z) EuW ₂ O ₈ ... (2)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, and z is a positive number satisfying 0.7 ≦ z <1.)
A red light-emitting phosphor, characterized in that
[4] A light-emitting device in which a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material, wherein the sealing material is any one of [1] to [3]. A red light-emitting phosphor dispersed therein,
[5] A light-emitting device in which a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material, and the light-emitting device emits light from the semiconductor light-emitting element. 3], a light emitting device comprising a fluorescent layer containing the red light emitting phosphor according to any one of
[6] The light-emitting device according to [5], wherein a fluorescent layer is provided on the semiconductor light-emitting element or the sealing material;
[7] The light emitting device according to [6], wherein the fluorescent layer is formed by dispersing the red light emitting phosphor in resin, rubber, elastomer, or glass.
I will provide a.
[0018]
The present invention will be described in detail below.
First, the 1st aspect of the red light emission fluorescent substance of this invention is demonstrated. The red light-emitting phosphor of the first aspect is a red light-emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (1)
Li _y A _(1-y) Eu _x Sm _(1-x) W ₂ O ₈ ... (1)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, x is a positive number satisfying 0.8 ≦ x <1, and y satisfies 0.4 ≦ y ≦ 1. (It is a positive number.)
It is represented by
[0019]
In the red light-emitting phosphor of the first aspect of the present invention, the red light-emitting phosphor represented by the composition formula (1) is such that y in the formula is in a range satisfying 0.4 ≦ y ≦ 1. Along with Li, at least one alkali metal selected from the group consisting of Na, K, Rb and Cs represented by A, preferably at least one alkali metal selected from the group consisting of Na and K, particularly preferably Na. It contains. That is, the red light-emitting phosphor of the present invention contains only Li as an alkali metal (in the case of y = 1), and further includes a group consisting of Na, K, Rb and Cs represented by A. One containing at least one alkali metal selected from the group consisting of Na and K, particularly preferably containing Na (when 0.4 ≦ y <1). In addition, y in the composition formula (1) is a range satisfying 0.4 ≦ y ≦ 1, but the range (lower limit) of y is preferably 0.6 or more, particularly preferably 0.7 or more, The range (upper limit) of y is preferably less than 1, particularly 0.9 or less.
[0020]
The red-emitting phosphor of the first aspect of the present invention contains Eu (europium) and Sm (samarium), and is represented by the composition formula (1). As, for example, the following composition formula (3),
LiEuW ₂ O ₈ ... (3)
A structure in which a part of Eu (Eu ion) site in the metal oxide crystal represented by the formula is substituted with Sm (Sm ion), and an alkali metal represented by A in the composition formula (1) (0.4 ≦ y <1), a part of the Li (Li ion) site in the crystal is further substituted with an alkali metal represented by A (an alkali metal ion represented by A). The thing of the structure which was made is mentioned. By making Eu and Sm coexist in the crystal, it becomes a red light emitting phosphor that exhibits high-intensity red light emission with excitation light of 400 to 410 nm, particularly around 405 nm, and further by making Li and Na coexist in the crystal. In particular, it becomes a red light emitting phosphor exhibiting high intensity red light emission.
[0021]
Furthermore, the ratio of Eu and Sm is a positive number satisfying x in the above composition formula (1) satisfying 0.8 ≦ x <1, preferably 0.9 ≦ x <1 (substitution rate from Eu ion to Sm ion) R is a ratio such that 0 <R ≦ 20 at%, preferably 0 <R ≦ 10 at%. When the value of x is less than 0.8 (when the substitution rate R exceeds 20%), sufficient red light emission cannot be obtained by the above-described excitation light of 400 to 410 nm, particularly around 405 nm.
[0022]
In the red-emitting phosphor according to the first aspect of the present invention, x in the composition formula (1) is 0.95 ≦ x <1, particularly 0.96 ≦ x <1, especially 0.96 ≦ x. It is preferable that it is a positive number satisfying ≦ 0.98 (the substitution rate R from Eu ions to Sm ions is 0 <R ≦ 5 at%, particularly 0 <R ≦ 4 at%, especially 2 ≦ R ≦ 4 at%). When x (substitution rate R) satisfies this range, this red light-emitting phosphor becomes a red light-emitting phosphor exhibiting particularly high-intensity red light emission by excitation light of 400 to 410 nm, particularly around 405 nm, and 350 With respect to excitation light in the range of ˜420 nm (that is, with respect to excitation light in a range wider than 400 to 410 nm), the emission intensity is equal to or higher than that of conventional phosphors, and the excitation wavelength is 350˜ This is preferable because it is an extremely excellent red light emitting phosphor exhibiting high light emission intensity in a wide range of 420 nm.
[0023]
Next, a second aspect of the red light emitting phosphor of the present invention will be described. The red light-emitting phosphor of the second embodiment is a red light-emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, and has the following composition formula (2)
Li _z A _(1-z) EuW ₂ O ₈ ... (2)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, and z is a positive number satisfying 0.7 ≦ z <1.)
It is represented by
[0024]
In the red light-emitting phosphor of the second aspect of the present invention, the red light-emitting phosphor represented by the composition formula (2) is such that z in the formula satisfies a range of 0.7 ≦ z <1. Along with Li, at least one alkali metal selected from the group consisting of Na, K, Rb and Cs represented by A, preferably at least one alkali metal selected from the group consisting of Na and K, particularly preferably Na. It contains. Note that z in the composition formula (2) is in a range satisfying 0.7 ≦ z <1, but this z range (lower limit) is preferably 0.8 or more, and z range (upper limit) ) Is preferably 0.99 or less, particularly preferably 0.95 or less.
[0025]
Moreover, the red light-emitting phosphor of the second aspect of the present invention contains an alkali metal represented by A in the above composition formula (2) together with Li as an alkali metal, and is represented by the above composition formula (2). As such, for example, the following composition formula (3),
LiEuW ₂ O ₈ ... (3)
A structure in which a part of the Li (Li ion) site in the metal oxide crystal represented by the formula (1) is substituted with an alkali metal represented by A (an alkali metal ion represented by A) is included. By allowing Li and Na to coexist in the crystal, a red light emitting phosphor exhibiting high-intensity red light emission with excitation light of 400 to 410 nm, particularly around 405 nm is obtained.
[0026]
In the present invention, the red light-emitting phosphor is a raw material such as an oxide or carbonate containing an element constituting the red light-emitting phosphor, such as Li ₂ CO ₃ , Na ₂ CO ₃ , Eu ₂ O ₃ , Sm ₂ O ₃ , W ₂ O ₃ Etc. are calcined in a stoichiometric ratio so as to have a predetermined composition represented by the above composition formula (1) or composition formula (2) after firing, and a raw material mixture obtained by mixing with a ball mill or the like is fired, necessary Depending on the case, it can be obtained by washing, grinding and sieving.
[0027]
The firing method can be a conventionally known method used for the production of a metal oxide used as a phosphor, and is not particularly limited. For example, the raw material mixture is placed in an alumina crucible, A method of producing by firing in a firing furnace such as a furnace may be employed. In this case, the firing temperature is preferably 800 to 1,000 ° C., particularly preferably 850 to 900 ° C., and the firing time is preferably 30 minutes to 48 hours, particularly preferably 2 to 12 hours.
[0028]
Furthermore, in the present invention, the alkali metal element in the red light emitting phosphor represented by the composition formula (1) or the composition formula (2), that is, Li and / or A (Na, K, Rb, and Cs). It is also preferred that a part of at least one selected from the group consisting of is substituted with at least one selected from the group consisting of Mg, Ca, Sr and Ba added as a coactivator. The substitution rate in this case is less than 0.5 (atomic ratio), preferably 0.3 (atomic ratio) in terms of the ratio of the total amount of Mg, Ca, Sr and Ba to the total amount of Li and A (Na, K, Rb and Cs). Ratio) or less, more preferably 0.2 (atomic ratio) or less, and particularly preferably 0.1 (atomic ratio) or less. In this case, the lower limit of the substitution rate is not particularly limited, but is preferably 0.01 (atomic ratio) or more, more preferably 0.05 (atomic ratio) or more.
[0029]
Next, the light emitting device of the present invention will be described.
First, the 1st aspect of the light-emitting device of this invention is demonstrated. The light-emitting device according to the first aspect is a light-emitting device in which a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material. A red light emitting phosphor is dispersed.
[0030]
Specifically, as shown in FIG. 1, leads 1 and 2, a semiconductor light emitting element 3 that emits light having a wavelength of 350 to 420 nm, and a lead thin wire 4 that electrically connects the semiconductor light emitting element 3 and the lead 2. Of a so-called shell-type light emitting diode having a structure sealed in a shell shape with a sealing material 5 or a pair of box-shaped light emitter housing members 6 having an open top surface as shown in FIG. The leads 1 and 2 are extended to the outside of the light emitter housing member 6, and the semiconductor light emitting element 3 and the lead

thin wires

4 and 4 that emit light having a wavelength of 350 to 420 nm are housed inside the light emitter housing member 6. Are obtained by dispersing the red light emitting phosphor of the present invention in a sealing material 5 such as a so-called chip-type light emitting diode having a structure in which the inside of the light emitting body housing member 6 is sealed with a sealing material 5. Can be mentioned.
[0031]
In this case, if only the above-described red light-emitting phosphor of the present invention is dispersed in the sealing material 5, a light-emitting device that emits red with high luminance is obtained. ₂ Al ₁₆ O ₂₇ : Eu, Mn, Zn ₂ GeO ₄ : Green light emitting phosphor such as Mn, BaMg ₂ Al ₁₆ O ₂₇ : Eu, (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ When dispersed together with a blue fluorescent light emitting material such as Cl: Eu, a light emitting device that emits white or intermediate color with high luminance is obtained. In any of these light emitting devices, red light emitting phosphors other than the red light emitting phosphor of the present invention, such as Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, 3.5MgO / 0.5MgF ₂ ・ GeO ₂ : Mn or the like can be added.
[0032]
This light-emitting device can be manufactured by mixing a phosphor with a sealing material such as resin, rubber, elastomer, or glass when sealing a semiconductor light-emitting element or the like. In particular, when a plurality of types of phosphors are used, the red light emitting phosphor of the present invention has a higher true specific gravity than a general phosphor, and therefore settles faster than other phosphors when mixed with a sealing material. May cause uneven color. Therefore, the red light-emitting phosphor of the present invention is mixed with a high viscosity material such as a silicone rubber composition or a silicone resin composition whose viscosity is adjusted with a thixotropy adjusting agent, and is cured by a method of curing the mixture. It is preferable to be dispersed. In addition to the phosphor described above as a color tone conversion material, pigments, dyes, pseudo pigments, and the like may be added to the sealing material.
[0033]
Next, a second aspect of the light emitting device of the present invention will be described. The light-emitting device according to the second aspect is a light-emitting device in which a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material, and the light emitted from the semiconductor light-emitting element. A fluorescent layer containing the above-described red light emitting phosphor of the present invention is provided on the road.
[0034]
As such a thing, what provided the fluorescent layer containing the red light emission fluorescent substance of this invention on a semiconductor light emitting element or a sealing material, for example is mentioned, Specifically, as shown in FIG. The

lead

1 and 2, the semiconductor light emitting device 3 that emits light having a wavelength of 350 to 420 nm, and the lead thin wire 4 that electrically connects the semiconductor light emitting device 3 and the lead 2 are sealed in a shell shape with a sealing material 5. A so-called shell-type light-emitting diode semiconductor light-emitting element 3 having a fluorescent layer 7 sealed with the semiconductor light-emitting element 3 and the like, and a box-shaped light-emitting body with an open top as shown in FIG. A pair of

leads

1 and 2 are extended from the inner bottom of the housing member 6 to the outside of the light emitter housing member 6, and the semiconductor light emitting element 3 and leads that emit light having a wavelength of 350 to 420 nm inside the light emitter housing member 6. Accommodates

fine wires

4 and 4 Subsequently, a phosphor layer 7 is provided on the semiconductor light emitting element 3 of a so-called chip-type light emitting diode having a structure in which the inside of the light emitter housing member 6 is sealed with the sealing material 5 and sealed together with the semiconductor light emitting element 3 and the like. 5, a bullet-type light emitting diode as shown in FIG. 5 provided with a fluorescent layer 7 so as to cover the sealing material 5, a chip type light emitting diode as shown in FIG. The thing which provided the fluorescent layer 7 on the sealing material 5 of this is mentioned. The configuration other than the fluorescent layer in FIGS. 5 and 6 is the same as the configuration shown in FIGS.
[0035]
Further, the fluorescent layer 7 is not limited to the so-called transmission type in which the fluorescent layer is provided in the light emitting diode or adjacent to the light emitting diode as described above, but the fluorescent layer 7 is separated from the light emitting diode 8 as shown in FIG. There is also a so-called reflection type light-emitting device that is provided at a position and reflects light emitted from the fluorescent layer by the reflection plate 9. Further, the fluorescent layer of the light emitting device in which the fluorescent layer is provided on the sealing material as shown in FIGS. 5 and 6 can be further sealed with the sealing material.
[0036]
In this case, if only the above-described red light-emitting phosphor of the present invention is dispersed in the fluorescent layer, a light-emitting device that emits high-brightness red is obtained. ₂ Al ₁₆ O ₂₇ : Eu, Mn, Zn ₂ GeO ₄ : Green light emitting phosphor such as Mn, BaMg ₂ Al ₁₆ O ₂₇ : Eu, (Sr, Ca, Ba) ₅ (PO ₄ ) ₃ When dispersed together with a blue fluorescent light emitting material such as Cl: Eu, a light emitting device that emits white or intermediate color with high luminance is obtained. In any of these light emitting devices, red light emitting phosphors other than the red light emitting phosphor of the present invention, such as Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, 3.5MgO / 0.5MgF ₂ ・ GeO ₂ : Mn or the like can be added.
[0037]
In addition, when providing a fluorescent layer on a semiconductor light-emitting device, the phosphor may be used as it is or may be mixed with a binder. In this case, as shown in FIGS. 3 and 4, the fluorescent layer is sealed in a sealing material together with the semiconductor light emitting element.
[0038]
On the other hand, when the fluorescent layer is provided on the sealing material, it is preferable to use the red light-emitting phosphor dispersed in a light-transmitting resin, rubber, elastomer or glass, particularly silicone resin or silicone rubber. In particular, when a plurality of types of phosphors are dispersed in the phosphor layer, as in the case of dispersing the red light-emitting phosphor of the present invention in the sealing material described above, a silicone rubber composition and a silicone resin whose viscosity is adjusted with a thixotropic modifier It is preferable to disperse in the phosphor layer by a method of mixing with a composition or the like and curing it. The fluorescent layer may be a single layer obtained by mixing phosphors, or may be a laminate of phosphors divided into several layers. In addition to the phosphor described above as a color tone conversion material, pigments, dyes, pseudo pigments, and the like may be added to the fluorescent layer.
[0039]
Since the light emitting device of the present invention uses the red light emitting phosphor represented by the composition formula (1) or the composition formula (2) as a red light emitting phosphor, the value of the highest external quantum efficiency of an InGaN-based element or the like is obtained. Is suitable as a light emitting device using an element having an emission wavelength of 400 to 410 nm, particularly around 405 nm. In particular, a red light-emitting phosphor represented by the above composition formula (1), where x is a positive number satisfying 0.95 ≦ x <1, or a red light-emitting phosphor represented by the above composition formula (2) is used. Since the light emitting device has a high emission intensity in a wide range of excitation wavelengths of 350 to 420 nm, it is not easily affected by fluctuations in the wavelength of the excitation light due to individual differences of the light emitting elements. For example, a green light emitting phosphor, a blue light emitting fluorescence When displaying a white or neutral color by emitting light from a semiconductor light emitting element that emits light of the above-mentioned wavelength in combination with a body, a delicate color is displayed with high reproducibility and high brightness. This is preferable.
[0040]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example.
[0041]
[Example 1]
As phosphor constituent raw materials, as shown in Table 1, WO ₃ 7.8112 g of powder, Eu ₂ O ₃ 2.9346 g of powder, Sm ₂ O ₃ 0.0294 g of powder, Li ₂ CO ₃ 0.6224 g of each powder was weighed and uniformly mixed with a ball mill to obtain a raw material mixture.
[0042]
Next, the obtained raw material mixture was put in an alumina crucible and fired at a temperature of 900 ° C. for 6 hours. The obtained fired product is thoroughly washed with pure water to remove unnecessary soluble components, and then finely pulverized with a ball mill, sieved (opening 53 μm), and LiEu. _0.99 Sm _0.01 W ₂ O ₈ A red light-emitting phosphor having a composition represented by
[0043]
With respect to this red light-emitting phosphor, emission intensity at each excitation wavelength was measured with a small spectrofluorometer FP-750 (manufactured by JASCO Corporation) under excitation at 380 nm, 395 nm and 405 nm. The results are shown in Table 1 and FIG.
[0044]
[Examples 2 to 6]
Eu ₂ O ₃ Powder and Sm ₂ O ₃ A red-emitting phosphor (LiEu) was prepared in the same manner as in Example 1 except that the amount of powder was as shown in Table 1. _0.98 Sm _0.02 W ₂ O ₈ (Example 2), LiEu _0.97 Sm _0.03 W ₂ O ₈ (Example 3), LiEu _0.96 Sm _0.04 W ₂ O ₈ (Example 4), LiEu _0.95 Sm _0.05 W ₂ O ₈ (Example 5), LiEu _0.90 Sm _0.10 W ₂ O ₈ (Example 6) was obtained, and the emission intensity was measured in the same manner as in Example 1. The results are shown in Table 1 and FIG. FIG. 9 shows the excitation spectrum of the red light-emitting phosphor obtained in Example 3, and FIG. 10 shows the X-ray diffraction pattern of the red light-emitting phosphor obtained in Example 6.
[0045]
[Example 7]
As phosphor constituent raw materials, as shown in Table 1, WO ₃ 7.8112 g of powder, Eu ₂ O ₃ 2.8456 g of powder, Sm ₂ O ₃ 0.1175 g of powder, Na ₂ CO ₃ 0.2679 g of powder, Li ₂ CO ₃ 0.4357 g of each powder was weighed, and these were uniformly mixed by a ball mill to obtain a raw material mixture.
[0046]
Next, the obtained raw material mixture was put in an alumina crucible and fired at a temperature of 900 ° C. for 6 hours. The obtained fired product is sufficiently washed with pure water to remove unnecessary soluble components, and then finely pulverized with a ball mill and sieved (opening 53 μm). _0.7 Na _0.3 Eu _0.96 Sm _0.04 W ₂ O ₈ A red light-emitting phosphor having a composition represented by
[0047]
With respect to this red light-emitting phosphor, emission intensity at each excitation wavelength was measured with a small spectrofluorometer FP-750 (manufactured by JASCO Corporation) under excitation at 380 nm, 395 nm and 405 nm. The results are shown in Table 1.
[0048]
[Comparative Example 1]
Eu ₂ O ₃ The amount of powder is as shown in Table 1, and Sm ₂ O ₃ LiEuW was prepared in the same manner as in Example 1 except that no powder was added. ₂ O ₈ A red light-emitting phosphor having a composition represented by the above was obtained, and the emission intensity was measured in the same manner as in Example 1. The results are shown in Table 1 and FIG. Further, FIG. 9 shows an excitation spectrum of this red light emitting phosphor, and FIG. 10 shows an X-ray diffraction pattern.
[0049]
[Table 1]

[0050]
From Table 1 and FIGS. 8 and 9, the red light-emitting phosphors of Examples 1 to 7, which are examples of the red light-emitting phosphor of the first aspect of the present invention, exhibit unprecedented high emission intensity at a wavelength of 405 nm. I understand that. In addition, Examples 1 to 5 and Example 7 in which x in the composition formula (1) is in the range of 0.95 ≦ x <1 are the conventional wavelengths shown in Comparative Example 1 in a wide range of wavelengths of 350 to 420 nm. In particular, Example 7 in which Na is contained as A in the composition formula (1) and y is 0.7 is in a wide range of 350 to 420 nm. It can be seen that the wavelength shows a high emission intensity far exceeding the conventional one shown in Comparative Example 1.
[0051]
Furthermore, as shown in FIG. 10, the X-ray diffraction pattern of the red light emitting phosphor of Example 6 containing the largest amount of Sm is LiEuW. ₂ O ₈ (The peak derived from Sm does not appear), the red light-emitting phosphor of the present invention is represented by the following formula (4).
LiEuW ₂ O ₈ (4)
It is supported that a part of Eu (Eu ion) site in the metal oxide crystal containing Eu represented by the formula is substituted with Sm (Sm ion).
[0052]
[Example 8]
As a phosphor constituting raw material, as shown in Table 2, WO ₃ 7.8112 g of powder, Eu ₂ O ₃ 2.9642 g of powder, Na ₂ CO ₃ 0.1786 g of powder, Li ₂ CO ₃ 0.4979 g of each powder was weighed, and these were uniformly mixed by a ball mill to obtain a raw material mixture.
[0053]
Next, the obtained raw material mixture was put in an alumina crucible and fired at a temperature of 900 ° C. for 6 hours. The obtained fired product is sufficiently washed with pure water to remove unnecessary soluble components, and then finely pulverized with a ball mill and sieved (opening 53 μm). _0.8 Na _0.2 EuW ₂ O ₈ A red light-emitting phosphor having a composition represented by
[0054]
With respect to this red light-emitting phosphor, emission intensity at each excitation wavelength was measured with a small spectrofluorometer FP-750 (manufactured by JASCO Corporation) under excitation at 380 nm, 395 nm and 405 nm. The results are shown in Table 2 together with the results of Comparative Example 1. Moreover, the excitation spectrum of the obtained red light-emitting phosphor is shown together with the spectrum of Comparative Example 1 in FIG.
[0055]
[Table 2]

[0056]
From Table 2 and FIG. 11, the red light-emitting phosphor of Example 8, which is an example of the red light-emitting phosphor of the second aspect of the present invention, exhibits an unprecedented high emission intensity at a wavelength of 405 nm and a wide range of 350 to 420 nm. It can be seen that the emission intensity is higher than the conventional one shown in Comparative Example 1 in the wavelength range.
[0057]
【The invention's effect】
As described above, the red light-emitting phosphor of the present invention exhibits an unprecedented high emission intensity at a wavelength of 400 to 410 nm, particularly around 405 nm, and is a light-emitting device that displays red, a green light-emitting phosphor, or blue light. For a light emitting device that displays white or intermediate color in combination with a phosphor, particularly a light emitting device using an element having an emission wavelength having the highest external quantum efficiency, such as an InGaN-based element, of 400 to 410 nm, particularly around 405 nm. When used, a light emitting device that emits red, white, or an intermediate color with high luminance can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an optical device of the present invention, and is a cross-sectional view showing a light emitting device in which a red light emitting phosphor of the present invention is dispersed in a shell type light emitting diode sealing material.
FIG. 2 is a diagram showing an example of the optical device of the present invention, and is a cross-sectional view showing a light emitting device in which the red light emitting phosphor of the present invention is dispersed in a sealing material of a chip type light emitting diode.
FIG. 3 is a diagram showing an example of the optical device of the present invention, and is a cross-sectional view showing a light emitting device in which a fluorescent layer containing the red light emitting phosphor of the present invention is provided on a semiconductor light emitting element of a shell-type light emitting diode. .
FIG. 4 is a diagram showing an example of the optical device of the present invention, and is a cross-sectional view showing a light emitting device in which a fluorescent layer containing the red light emitting phosphor of the present invention is provided on a semiconductor light emitting element of a chip type light emitting diode. .
FIG. 5 is a diagram showing an example of an optical device according to the present invention, and is a cross-sectional view showing a light emitting device in which a phosphor layer containing the red light emitting phosphor according to the present invention is provided on a sealing material for a shell-shaped light emitting diode. .
FIG. 6 is a diagram showing an example of the optical device of the present invention, and is a cross-sectional view showing a light emitting device in which a phosphor layer containing the red light emitting phosphor of the present invention is provided on a sealing material of a chip type light emitting diode. .
FIG. 7 is a diagram showing an example of the optical device of the present invention, and is a cross-sectional view showing a light emitting device that provides a fluorescent layer at a position spaced from a light emitting diode and reflects light emitted from the fluorescent layer.
8 is a graph in which the emission intensity of excitation light at 380 nm, 395 nm, and 405 nm of the red light emitting phosphors of Examples 1 to 6 and Comparative Example 1 is plotted against the substitution rate of Sm. FIG.
9 is an excitation spectrum of the red light-emitting phosphor of Example 3 and Comparative Example 1. FIG.
10 is an X-ray diffraction pattern of red light emitting phosphors of Example 6 and Comparative Example 1. FIG.
11 is an excitation spectrum of red light emitting phosphors of Example 8 and Comparative Example 1. FIG.
[Explanation of symbols]
1, 2 lead
3 Semiconductor light emitting device
4 Lead wire
5 Sealing material
6 Light emitter housing member
7 Fluorescent layer
8 Light emitting diode
9 Reflector

Claims

A red light-emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, the composition formula (1)
Li _y A _(1-y) Eu _x Sm _(1-x) W ₂ O ₈ (1)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, x is a positive number satisfying 0.8 ≦ x <1, and y satisfies 0.4 ≦ y ≦ 1. (It is a positive number.)
A red light-emitting phosphor characterized by the following:

2. The red light-emitting phosphor according to claim 1, wherein x in the composition formula (1) is a positive number satisfying 0.95 ≦ x <1.

A red light emitting phosphor that emits light when excited by light having a wavelength of 350 to 420 nm, the composition formula (2)
Li _z A _(1-z) EuW ₂ O ₈ (2)
(In the formula, A is at least one selected from the group consisting of Na, K, Rb and Cs, and z is a positive number satisfying 0.7 ≦ z <1.)
A red light-emitting phosphor characterized by the following:

4. The red light-emitting fluorescent material according to claim 1, wherein a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material. A light-emitting device in which a body is dispersed.

4. A light-emitting device in which a semiconductor light-emitting element that emits light having a wavelength of 350 to 420 nm is sealed in a sealing material, and the light-emitting device emits light from the semiconductor light-emitting element. A light emitting device comprising a fluorescent layer containing the red light emitting phosphor according to 1.

6. The light emitting device according to claim 5, wherein a fluorescent layer is provided on the semiconductor light emitting element or the sealing material.

7. The light emitting device according to claim 6, wherein the fluorescent layer is formed by dispersing the red light emitting phosphor in resin, rubber, elastomer or glass.