CN108251111B - Mn (manganese)4+Doped tungstate red fluorescent powder and preparation method thereof - Google Patents

Abstract

The invention discloses a Mn ⁴⁺ doped tungstate red fluorescent powder and a preparation method thereof. The red fluorescent powder uses Al powder as a reducing agent, and has excellent luminescence performance through non-contact reduction treatment, and can better Applied to white light LED devices, the phosphor is (CaO, SrO, BaO)‑(WO ₃ , MoO ₃ , SiO ₂ , TiO ₂ , GeO ₂ )‑MnO ₂ system, which is a brand-new UV-excited red phosphor. The system components do not contain rare earth elements, and the manufacturing cost of the phosphor is low. The preparation method adopts remote Al powder reduction, which not only has the advantages of safety, high efficiency, and energy saving, but also can effectively control the spectrum of the phosphor, which greatly improves the performance of the phosphor. quantum efficiency.

Description

A kind of Mn4+ doped tungstate red phosphor and preparation method thereof

technical field

The invention relates to the technical field of fluorescent powder, in particular to a Mn ⁴⁺ doped tungstate red fluorescent powder and a preparation method thereof.

Background technique

White LEDs have significant advantages such as low power consumption, high efficiency, green environmental protection, energy saving, long life, small size, fast response, and good color rendering, so they are known as green lighting sources in the 21st century, with broad market prospects and huge The social and economic benefits have been widely concerned by the industry.

Generally speaking, there are three paths for LEDs to achieve white light emission: the first is to mix three colors of LED light; the second is to use ultraviolet LED lamps to excite three kinds of phosphors, red, green and blue, and mix the light of these three kinds of phosphors into white light. ; The third is the use of blue LEDs and the corresponding blue light excited yellow phosphors. Currently, a third way to achieve white light has been commercialized using InGaN chips emitting 450-470 nm blue light and surface-coated blue-excited Y ₃ A ₁₅ O ₁₂ :Ce ³⁺ (YAG:Ce ³⁺ ) that emits yellow light phosphor. However, the high color temperature and low color rendering index of white light due to the lack of red light components inevitably limit its application in indoor lighting. Therefore, it has become a trend to study a red phosphor that can be used in LEDs.

Currently, Eu ²⁺ doped nitride phosphors (eg, CaAlSiN ₃ : Eu ²⁺ ) have received more and more attention due to their high efficiency and high stability, and have been commercialized. However, due to its severe reabsorption and high synthesis costs, researchers have turned more attention to non-rare earth Mn ⁴⁺ doped red phosphors, which not only have low synthesis costs, but also have ideal spectra. nature. As a transition metal ion, Mn ⁴⁺ has an unfilled 3d ³ electron shell, and all species doped with Mn ^{4+ exhibit broad excitation and narrow emission bands due to the obvious electronic configuration of Mn 4+ .} Mn ⁴⁺ -doped fluoride red phosphors have become a new research direction due to their narrow-band emission of red light, excitation by ultraviolet and blue light, and cheap raw materials. Moreover, toxic HF is used, and the physical properties are unstable. Therefore, researchers at home and abroad have carried out a lot of research work on Mn ⁴⁺ doped oxide red phosphors. At present, the methods for preparing Mn ⁴⁺ doped oxide red phosphors include solid-phase reaction method, sol-gel method, etc., but the luminescence intensity of the phosphor obtained by the above method is weak. At present, there is no report on the preparation of Mn ⁴⁺ -doped (CaO, SrO, BaO)-(WO ₃ , MoO ₃ , SiO ₂ , TiO ₂ , GeO ₂ )-MnO2 system red phosphors using Al reduction method.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a Mn ⁴⁺ doped tungstate red phosphor and a preparation method thereof. The red phosphor uses Al powder as a reducing agent, and has excellent luminescence performance through non-contact reduction treatment, and can be more It is well applied to white light LED devices. The phosphor is a (CaO, SrO, BaO)-(WO ₃ , MoO ₃ , SiO ₂ , TiO ₂ , GeO ₂ )-MnO ₂ system, which is a brand-new UV-excited red phosphor without rare earth elements. element, the manufacturing cost of the phosphor is low. The preparation method adopts remote Al powder reduction, which not only has the advantages of safety, high efficiency, and energy saving, but also can effectively control the spectrum of the phosphor, and greatly improve the quantum efficiency of the phosphor.

In order to achieve the above object, the present invention provides a method for preparing a Mn ⁴⁺ doped tungstate red phosphor, which is characterized in that it includes the following steps:

(1) First, weigh a certain quality of raw material powder, place it in an agate mortar and grind for 30-60 minutes, then put it into a quartz crucible, and heat it in a high-temperature furnace at 1250-1300 °C for 4-10 hours through a solid-phase reaction, Cool to room temperature to obtain the precursor, wherein the composition of the powder raw material is (in terms of oxide mass percentage): 0%<CaO+SrO+BaO≤76.17%, 0%<MoO ₃ +WO ₃ +SiO ₂ +TiO ₂ +GeO ₂ ≤57.95%, 0%<MnO ₂ ≤0.14%;

(2) Using Al powder as the reducing agent, place the Al powder and the precursor in the crucible boat respectively, and place them in the vacuum tube furnace. After heat treatment, after reduction for 6 hours, and cooling to room temperature naturally, the Mn ⁴⁺ doped tungstate red phosphor is obtained.

Preferably, in the above step (2), the mass ratio of the reducing agent Al powder to the precursor is (0.03-1):1.

Preferably, in the above step (2), the crucible boat is placed in parallel left and right in the vacuum tube furnace.

Preferably, in the above step (2), the distance between the centers of the crucible boats placed in parallel on the left and right is not more than 10 cm.

Preferably, in the above step (2), during the whole preparation process, the Al powder and the precursor are always separated and not in contact.

The present invention also provides a Mn ⁴⁺ doped tungstate red phosphor prepared by the above preparation method.

The Mn ⁴⁺ doped tungstate red fluorescent powder and the preparation method thereof provided by the present invention have the following beneficial effects.

1. A Mn ⁴⁺ doped tungstate red phosphor provided by the present invention, the red phosphor uses Al powder as a reducing agent, and has excellent luminescence performance through non-contact reduction treatment, and can be better applied to White LED devices.

2. A Mn ⁴⁺ doped tungstate red phosphor provided by the present invention is (CaO, SrO, BaO)-(WO ₃ , MoO ₃ , SiO ₂ , TiO ₂ , GeO ₂ )- The MnO ₂ system is a brand-new UV-excited red phosphor. The system components do not contain rare earth elements, and the manufacturing cost of the phosphor is low.

3. The preparation method of a Mn ⁴⁺ -doped tungstate red phosphor provided by the present invention adopts tungstate as a host material, and tungstate is a typical self-activating luminescent material, and its luminescence spectrum is very stable, The intrinsic emission band is broad, occupying most of the visible region, and the cations in tungstate can strongly influence the position of the emission band.

4. The preparation method of a Mn ⁴⁺ doped tungstate red phosphor provided by the present invention adopts remote Al powder reduction, and uses Al powder as the local regular reaction of the reducing agent, which can effectively regulate the localization of the crystal field. Domain coordination and chemical pressure can be used to optimize the spectral performance of the phosphor. The preparation method not only has the advantages of safety, high efficiency, and energy saving, but also can effectively control the spectrum of the phosphor and greatly improve the quantum efficiency of the phosphor.

Description of drawings

Figure 1 shows the spectral curves of Mn ⁴⁺ -doped tungstate red phosphors prepared at different reduction temperatures.

Detailed ways

The present invention will be further described below with reference to specific embodiments and accompanying drawings to help understand the content of the present invention.

The invention provides a preparation method of Mn ⁴⁺ doped tungstate red phosphor, comprising the following steps:

(1) First, weigh a certain quality of raw material powder, place it in an agate mortar and grind for 30-60 minutes, then put it into a quartz crucible, and heat it in a high-temperature furnace at 1250-1300 ℃ for 4-10 hours through solid-phase reaction, Cool to room temperature to obtain the precursor, wherein the composition of the powder raw material is (in terms of oxide mass percentage): 0%<CaO+SrO+BaO≤76.17%, 0%<MoO ₃ +WO ₃ +SiO ₂ +TiO ₂ +GeO ₂ ≤57.95%, 0%<MnO ₂ ≤0.14%;

(2) Weigh Al powder and precursor according to the mass ratio of Al powder to precursor (0.03～1): 1, place Al powder and precursor in a crucible boat respectively, and place them in a vacuum tube furnace. After the system is evacuated to less than 0.1MPa, heat treatment is performed at 0-900°C, and after reduction for 6 hours, it is naturally cooled to room temperature to obtain Mn ⁴⁺ doped tungstate red phosphor. In the whole preparation process, the Al powder and the precursor are always separated and not in contact, and the crucible boats are placed in parallel left and right in the vacuum tube furnace, and the distance between the centers of the crucible boats placed in parallel is not more than 10cm.

The present invention provides a method for preparing Mn ⁴⁺ doped tungstate red fluorescent powder, using tungstate as a host material, tungstate is a typical self-activating luminescent material, its luminescence spectrum is very stable, and its intrinsic emission The spectral bands are broad, occupying most of the visible region, and cations in tungstate can strongly influence the position of the emission band.

The present invention provides a method for preparing Mn ⁴⁺ doped tungstate red fluorescent powder, which adopts remote Al powder reduction, and uses Al powder as a reducing agent for a local regular reaction, which can effectively control the local distribution of the crystal field. This preparation method not only has the advantages of safety, high efficiency and energy saving, but also can effectively control the spectrum of the phosphor, and greatly improve the quantum efficiency of the phosphor.

The present invention also provides a Mn ⁴⁺ doped tungstate red phosphor prepared by the above preparation method. The red phosphor uses Al powder as a reducing agent, and has excellent luminescence performance through non-contact reduction treatment. It can be better applied to white light LED devices. The phosphor is a (CaO, SrO, BaO)-(WO ₃ , MoO ₃ , SiO ₂ , TiO ₂ , GeO ₂ )-MnO ₂ system, which is a brand-new UV-excited red phosphor without rare earth elements. element, the manufacturing cost of the phosphor is low.

The following examples are the specific preparation process of Mn ⁴⁺ doped tungstate red phosphor:

Example 1:

(1) First, weigh a certain quality of raw material powder (CaO=0.4213g, WO3 ₌ 0.5776g, _MnO2 =0.0011g), put it in an agate mortar and grind for 30-60min, then put it into a quartz crucible, pass it through The solid-phase reaction is heated in a high temperature furnace at 1250-1300 ℃ for 4-10 hours, and cooled to room temperature to obtain a precursor.

(2) Weigh 0.3 g of Al powder and 1 g of the precursor, place the Al powder and the precursor in a crucible boat respectively, and place them in a vacuum tube furnace. After the entire system is evacuated to less than 0.1 MPa, the temperature of Mn ⁴⁺ doped tungstate red phosphor is obtained by heat treatment, and after reduction for 6 h, and then naturally cooled to room temperature. In the whole preparation process, the Al powder and the precursor are always separated and not in contact, and the crucible boats are placed in parallel left and right in the vacuum tube furnace, and the distance between the centers of the crucible boats placed in parallel on the left and right does not exceed 10 cm.

Example 2:

(1) First, weigh a certain quality of raw material powder (SrO=0.5736g, WO ₃ =0.4256g, MnO ₂ =0.0008g), put it in an agate mortar and grind for 30-60 minutes, then put it into a quartz crucible, pass The solid-phase reaction is heated in a high temperature furnace at 1250-1300 ℃ for 4-10 hours, and cooled to room temperature to obtain a precursor.

(2) Weigh 0.3 g of Al powder and 1 g of the precursor, place the Al powder and the precursor in a crucible boat respectively, and place them in a vacuum tube furnace. After the whole system is evacuated to less than 0.1 MPa, the temperature is 800 ° C. Mn ⁴⁺ doped tungstate red phosphor is obtained by heat treatment, and after reduction for 6 h, and then naturally cooled to room temperature. In the whole preparation process, the Al powder and the precursor are always separated and not in contact, and the crucible boats are placed in parallel left and right in the vacuum tube furnace, and the distance between the centers of the crucible boats placed in parallel is not more than 10cm.

Example 3:

(1) First, weigh a certain quality of raw material powder (BaO=0.6656g, WO ₃ =0.3338g, MnO ₂ =0.0006g), place it in an agate mortar and grind for 30-60 minutes, then put it into a quartz crucible, pass The solid-phase reaction is heated in a high temperature furnace at 1250-1300 ℃ for 4-10 hours, and cooled to room temperature to obtain a precursor.

(2) Weigh 0.3 g of Al powder and 1 g of the precursor, place the Al powder and the precursor in a crucible boat respectively, and place them in a vacuum tube furnace. After the entire system is evacuated to less than 0.1 MPa, the temperature is 900 ° C. Mn ⁴⁺ doped tungstate red phosphor is obtained by heat treatment, and after reduction for 6 h, and then naturally cooled to room temperature. In the whole preparation process, the Al powder and the precursor are always separated and not in contact, and the crucible boats are placed in parallel left and right in the vacuum tube furnace, and the distance between the centers of the crucible boats placed in parallel is not more than 10cm.

Effects of different reduction temperatures on the spectral properties and quantum efficiency of Mn ⁴⁺ -doped tungstate red phosphors:

(1) Weigh SrO, WO ₃ , MnO ₂ powder raw materials (in terms of oxide mass percentage) (see Table 1 for specific implementation cases), place them in an agate mortar and grind them uniformly, put them in a quartz crucible, and pass the solid Instead, it should be heated in a high temperature furnace at 1300°C for 8 hours and cooled to room temperature to obtain the precursor.

(2) Weigh 0.3g of Al powder and 1g of precursor according to the mass ratio of Al powder to precursor 0.3:1, place them in a crucible boat respectively, and place them in a vacuum tube furnace, and place them in parallel on the left and right (Al powder and 1 g of precursor). The precursors are placed separately, always separated and not in contact, and the distance between the centers of the crucible boats does not exceed 10cm), after the whole system is evacuated to less than 0.1MPa, heat treatment is performed at 0 ~ 900 ℃, and after reduction for 6h, Naturally cooled to room temperature to obtain Mn ⁴⁺ doped tungstate red phosphors (see Table 1 for specific implementation examples).

(3) Using a fluorescence spectrometer (HITACHI F-7000) to test the spectral properties of the red phosphor of the system, the results show that the strongest excitation peak of the phosphor is located at 330 nm, and under the excitation of the excitation wavelength light, it shows the strongest emission wavelength The emission of red light at 695 nm indicates that the phosphor is a red phosphor under excitation at 330 nm. Under the same test conditions, the luminescence position did not change at different Al powder reduction temperatures, and the spectral intensity changed significantly (as shown in Figure 1).

(4) Using the quantum efficiency accessory (S68) of the fluorescence spectrometer (HITACHI F-7000) to test the quantum efficiency of the sample, under the excitation of 330nm wavelength ultraviolet light, the measured quantum efficiency of the sample is 4.9% (Example 1), 5.8% (implementation case 2), 6.2% (implementation case 3), 23.4% (implementation case 4), 7.7% (implementation case 5).

Table 1. Preparation conditions and spectral properties of prepared samples for different implementation cases

Specific examples are used herein to describe the inventive concept in detail, and the descriptions of the above embodiments are only used to help understand the core idea of the present invention. It should be pointed out that for those skilled in the art, any obvious modifications, equivalent replacements or other improvements made without departing from the inventive concept should be included within the protection scope of the present invention.

Claims (6)

1. the preparation method of the tungstate red phosphor of a kind of Mn ⁴⁺ doping, is characterized in that, comprises the steps: (1) First, weigh a certain quality of raw material powder, place it in an agate mortar and grind for 30-60 minutes, then put it into a quartz crucible, and heat it in a high-temperature furnace at 1250-1300 °C for 4-10 hours through a solid-phase reaction, Cooling to room temperature to obtain a precursor, wherein the composition of the powder raw material is: CaO=0.4213g, WO ₃ =0.5776g, MnO ₂ =0.0011g; (2) Using Al powder as the reducing agent, place the Al powder and the precursor in the crucible boat respectively, and place them in a vacuum tube furnace. After the entire system is evacuated to less than 0.1 MPa, heating is performed at 600°C. After treatment, after reduction for 6 hours, it was naturally cooled to room temperature, and the Mn ⁴⁺ doped tungstate red phosphor was obtained. 2. the preparation method of a kind of Mn ⁴⁺ doped tungstate red phosphor according to claim 1, is characterized in that, in described step (2), the mass ratio of reducing agent Al powder and precursor is 0.3:1. 3. the preparation method of a kind of Mn ⁴⁺ doped tungstate red phosphor according to claim 1 and 2, is characterized in that, in described step (2), the crucible boat is left and right parallel in the vacuum tube furnace place. 4. the preparation method of a kind of Mn ⁴⁺ doped tungstate red phosphor according to claim 3, is characterized in that, in described step (2), the mutual center distance of the crucible boats placed in parallel on the left and right is not the same. more than 10cm. 5. The preparation method of a Mn ⁴⁺ -doped tungstate red phosphor according to claim 4, wherein in the step (2), in the whole preparation process, the Al powder and the precursor are always Separate, do not touch. 6. A Mn ⁴⁺ doped tungstate red phosphor prepared by the preparation method of any one of claims 1-5.

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