CN103497768A - Near-ultraviolet excited molybdenum-tungsten borate red fluorescent powder and preparation method thereof - Google Patents

Abstract

The invention discloses a near ultraviolet excited molybdenum tungsten borate red fluorescent powder and a preparation method thereof. The near-ultraviolet excited molybdenum tungsten borate red phosphor is based on Gd ₃ BW _1-x Mo _x O ₉ , with rare earth ion Eu ³⁺ as the active ion, and the chemical composition is Gd _3-y BW _1-x Mo _x O ₉ : Eu ³⁺ _y , where 0.15≤x≤0.4, 0.06≤y≤3. During preparation, the raw materials Gd ₂ O ₃ , H ₃ BO ₃ , WO ₃ , Mo ₂ O ₃ , and Eu ₂ O ₃ are weighed according to the metering ratio. Mix the weighed raw materials, grind them evenly, put the mixture in a temperature-programmed box-type resistance furnace, pre-fire twice, and then sinter for the third time at 1150-1250°C, cool to room temperature with the furnace, take out and grind . The near-ultraviolet excited molybdenum tungsten borate red fluorescent powder of the present invention has high luminous brightness, good red light color purity, good luminous thermal stability, and the preparation process is environmentally friendly and pollution-free.

Description

A near-ultraviolet excited molybdenum tungsten borate red phosphor and preparation method thereof

technical field

The invention relates to a red fluorescent powder, in particular to a red fluorescent powder with molybdenum tungsten borate as a matrix that can be effectively excited by near ultraviolet light and a preparation method thereof. The invention belongs to the technical field of rare earth luminescent materials.

Background technique

White LED has become a research hotspot in the field of lighting due to its advantages of small size, energy saving and environmental protection, long life and fast response rate. There are three recognized ways to prepare white LEDs using phosphors: the first is to use GaN-based blue LEDs to excite YAG:Ce ³⁺ yellow phosphors to produce white light. The white LED obtained in this way has low color rendering index R _a (CRI, 60-75) and high color temperature due to the lack of red components in the spectrum, and the light color is unstable. The second is to use blue LEDs to excite green and red phosphors to produce white light. This method has a better color rendering effect, but still has the problem of unstable light color. The third is to use violet or near-ultraviolet LEDs to excite red, green, and blue phosphors to produce white light. This white light LED can simultaneously have a high color rendering index _Ra (>90) and high lumen efficiency, and the light color Stability is the mainstream development direction of white LED. The development of high-efficiency phosphors is the core of obtaining white light LEDs. The current commercial red phosphor has very low absorption efficiency in the near-ultraviolet band, such as Y ₂ O ₂ S:Eu ³⁺ , which makes the luminous efficiency of the red phosphor in the third method lower than that of the corresponding blue and red phosphors. The main problem with the method. In addition, the chemical stability of the red phosphor Y ₂ O _{2 S} :Eu ³⁺ is poor under the excitation of near-ultraviolet light. These deficiencies of red phosphors have become a bottleneck for the development of near-ultraviolet excited white LEDs. Therefore, it is an urgent task to develop red phosphors for white LEDs that can be effectively excited by near-ultraviolet light.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a near-ultraviolet excited molybdenum tungsten borate red phosphor and its preparation method. The obtained phosphor has excellent optical properties, environmental protection, simple preparation process and low cost. .

The object of the present invention is achieved through the following technical solutions:

A near-ultraviolet excited molybdenum tungsten borate red phosphor, with Gd ₃ BW _1-x Mo _x O ₉ as the matrix, rare earth ion Eu ³⁺ as the active ion, and the chemical composition is Gd _3-y BW _1-x Mo _x O ₉ : Eu ³⁺ _y , where 0.15≤x≤0.4, 0.06≤y≤3.

The preparation method of the molybdenum tungsten borate red fluorescent powder excited by the near ultraviolet comprises the following steps:

(1) The chemical composition of molybdenum tungsten borate red phosphor excited by near ultraviolet is Gd _3-y BW _1-x Mo _x O ₉ : Eu ³⁺ _y , where 0.15≤x≤0.4,0.06≤y≤3 For the stoichiometric ratio of each element, weigh the corresponding raw materials Gd ₂ O ₃ , H ₃ BO ₃ , WO ₃ , Mo ₂ O ₃ , Eu ₂ O ₃ , mix the raw materials and grind them evenly in an agate mortar to obtain the precursor body mixture.

(2) Place the precursor mixture in a temperature-programmed box-type resistance furnace for the first sintering at a temperature of 500°C to 600°C, and cool the sintered material to room temperature with the furnace, then take it out and grind it; then grind the The material is sintered for the second time at 1000-1100°C, cooled to room temperature with the furnace, and then taken out for grinding; then the ground material is sintered for the third time at 1150-1250°C, cooled to room temperature with the furnace, taken out for grinding , to obtain molybdenum tungsten borate red phosphor excited by near ultraviolet light.

In order to further realize the purpose of the present invention, said 0.15≤x≤0.3.

The first sintering is to place the precursor mixture in a temperature-programmed box-type resistance furnace, raise the temperature to 500-600°C at a rate of 1°C/min-3°C/min, and keep the temperature for 4-6h.

The second sintering is to place the ground material in a temperature-programmed box-type resistance furnace, raise the temperature to 1000-1100°C at a rate of 1°C/min-3°C/min, and keep the temperature for 10-12h.

The third sintering is to place the ground material in a temperature-programmed box-type resistance furnace, raise the temperature to 1150-1250°C at a rate of 1°C/min-3°C/min, and keep the temperature for 10-12h.

The near-ultraviolet-excited molybdenum tungsten borate red fluorescent powder involved in the present invention has strong absorption in the near-ultraviolet region, and energy can be well transferred to doped Eu ³⁺ , thereby emitting red light with superior performance.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The luminous intensity of the molybdenum tungsten borate red phosphor excited by near-ultraviolet provided by the present invention is much higher than that of the current commercial red phosphor Y ₂ O ₂ S:Eu ³⁺ , and the luminous efficiency under excitation at 385nm is higher than that of the commercial Y ₂ O ₂ S: more than 10 times that of Eu ³⁺ .

(2) The molybdenum tungsten borate red fluorescent pink color coordinates close to the NTSC standard value excited by the near ultraviolet light provided by the present invention, and the red light is pure.

(3) The near-ultraviolet-excited molybdenum tungsten borate red phosphor powder provided by the present invention has excellent luminous thermal stability, and can maintain the original luminous intensity up to 200°C.

Description of drawings

Fig. 1 is the XRD spectrum of the near-ultraviolet excited molybdenum tungsten borate red phosphor Gd _2.94 BW _0.85 O ₉ : Eu _0.06 , Mo _0.15 obtained in Example 1 of the present invention.

Figure 2 shows the near-ultraviolet excited molybdenum tungsten borate red phosphor Gd _2.94 BW _0.85 O ₉ : Eu _0.06 , Mo _0.15 (red solid line) obtained in Example 1 of the present invention and the current commercial red phosphor Y ₂ O ₂ S :Eu ³⁺ (blue solid line), emission spectrum obtained at an excitation wavelength of 385nm. The inset of Fig. 2 is a graph showing the variation of the emission intensity at 616 nm with temperature when the sample is excited at a wavelength of 385 nm.

Fig. 3 is the excitation spectrum of molybdenum tungsten borate red phosphor Gd _2.94 BW _0.85 O ₉ : Eu _0.06 , Mo _0.15 obtained in Example 1 of the present invention excited by near-ultraviolet and monitored at an emission wavelength of 615 nm.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example 1

Accurately weigh 1.0658g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3942g WO ₃ , 0.0432g MoO ₃ , 0.0211g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture . The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 500°C at a rate of 2°C/min, kept for 5 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1100°C at a rate of 2°C/min, and keep it warm for 10 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. Raise the obtained sample to 1200°C at a rate of 2°C/min, keep it warm for 10 hours, take it out and grind it to obtain a Gd _2.94 BW _0.85 O ₉ :Eu _0.06 , Mo _0.15 sample.

该图1能证明本实施例所得的产物组成为Gd_2.94BW_0.85O₉：Eu_0.06,Mo_0.15。其激发(发射波长为615nm)见图3，图3说明该荧光粉能被310-420nm波段的近紫外光有效激发。其与当前商业用红色荧光粉Y₂O₂S:Eu³⁺在385nm波长激发下的发射光谱的比较见图3，从图中可知，该荧光粉发射主峰位于616nm，红光纯正，色坐标值为（0.64，0.35）。且其发光效率是商用Y₂O₂S:Eu³⁺的10倍以上。图3插图为该荧光粉616nm发射强度的随温度变化的曲线图。强度在200℃以内基本不随温度变化，说明该近紫外激发的钼钨硼酸盐红色荧光粉具有优异的发光热稳定性。The XRD pattern of the Gd _2.94 BW _0.85 O ₉ : Eu _0.06 , Mo _0.15 powder prepared in this example is shown in FIG. 1 . The XRD result of this product is completely consistent with the diffraction peak of ICSD250417, indicating that the sample has a hexagonal crystal structure, and the unit cell parameters are

Figure 1 can prove that the composition of the product obtained in this example is Gd _2.94 BW _0.85 O ₉ : Eu _0.06 , Mo _0.15 . Its excitation (emission wavelength is 615nm) is shown in Figure 3, which shows that the phosphor can be effectively excited by near-ultraviolet light in the 310-420nm band. The comparison between it and the emission spectrum of the current commercial red phosphor Y ₂ O ₂ S:Eu ³⁺ under the excitation of 385nm wavelength is shown in Figure 3. It can be seen from the figure that the main emission peak of this phosphor is located at 616nm, the red light is pure, and the color coordinates The value is (0.64, 0.35). And its luminous efficiency is more than 10 times that of commercial Y ₂ O ₂ S:Eu ³⁺ . The illustration in Fig. 3 is a graph showing the variation of the 616nm emission intensity of the phosphor with temperature. The intensity basically does not change with the temperature within 200°C, indicating that the near-ultraviolet excited molybdenum tungsten borate red phosphor has excellent thermal stability of luminescence.

Example 2

Accurately weigh 1.0658g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3478g WO ₃ , 0.0720g MoO ₃ , 0.0211g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture . The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 600°C at a rate of 2°C/min, kept for 6 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1100°C at a rate of 2°C/min, and keep it warm for 10 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. The obtained samples were raised to 1150°C at a rate of 2°C/min, held for 12 hours, taken out and ground to obtain Gd _2.94 BW _0.75 O ₉ :Eu _0.06 , Mo _0.25 samples.

The Gd _2.94 BW _0.75 O ₉ : Eu _0.06 , Mo _0.25 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as in Example 1, but the intensity is slightly enhanced than that of Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Example 3

Accurately weigh 1.0658g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3709g WO ₃ , 0.0576g MoO ₃ , 0.0211g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture . The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 500°C at a rate of 2°C/min, kept for 4 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1000°C at a rate of 2°C/min and keep it warm for 12 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. The obtained samples were raised to 1200°C at a rate of 2°C/min, held for 10 hours, taken out and ground to obtain Gd _2.94 BW _0.8 O ₉ : Eu _0.06 , Mo _0.2 samples.

The Gd _2.94 BW _0.8 O ₉ :Eu _0.06 , Mo _0.2 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as Example 1, but the intensity is all enhanced than Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Example 4

Accurately weigh 0.7975g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3709g WO ₃ , 0.0576MoO ₃ , and 0.2816g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture. The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 500°C at a rate of 2°C/min, kept for 5 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1050°C at a rate of 2°C/min and keep it warm for 11 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. The obtained samples were raised to 1200°C at a rate of 2°C/min, held for 11 hours, taken out and ground to obtain Gd _2.2 BW _0.8 O ₉ :Eu _0.8 , Mo _0.2 samples.

The Gd _2.2 BW _0.8 O ₉ :Eu _0.8 , Mo _0.2 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as Example 1, but the intensity is all enhanced than Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Example 5

Accurately weigh 0.7975g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3709g WO ₃ , 0.0576MoO ₃ , and 0.2816g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture. The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 550°C at a rate of 2°C/min, kept for 5 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1100°C at a rate of 2°C/min, and keep it warm for 10 hours; take it out after cooling to room temperature with the furnace, and carry out the third grinding. The obtained samples were raised to 1150°C at a rate of 2°C/min, held for 10 hours, taken out and ground to obtain Gd _2.2 BW _0.8 O ₉ : Eu _0.8 , Mo _0.2 samples.

The Gd _2.2 BW _0.8 O ₉ :Eu _0.8 , Mo _0.2 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as Example 1, but the intensity is all enhanced than Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Example 6

Accurately weigh 0.7975g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.3709g WO ₃ , 0.0576MoO ₃ , and 0.2816g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture. The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 500°C at a rate of 2°C/min, kept for 5 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1100°C at a rate of less than 2°C/min, and keep it warm for 10 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. The obtained samples were raised to 1250°C at a speed of 2°C/min, held for 10 hours, taken out and ground to obtain Gd _2.2 BW _0.8 O ₉ :Eu _0.8 , Mo _0.2 samples.

The Gd _2.2 BW _0.8 O ₉ :Eu _0.8 , Mo _0.2 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as Example 1, but the intensity is all enhanced than Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Example 7

Accurately weigh 1.0658g Gd ₂ O ₃ , 0.1422g H ₃ BO ₃ , 0.2782g WO ₃ , 0.1152g MoO ₃ , 0.0211g Eu ₂ O ₃ , mix the above raw materials and grind them evenly in an agate mortar to obtain a precursor mixture . The precursor mixture was placed in a temperature-programmed box-type resistance furnace, and the temperature was raised to 600°C at a rate of 2°C/min, kept for 4 hours, cooled to room temperature with the furnace, and then taken out for grinding again. Raise the obtained powder to 1100°C at a rate of 2°C/min and keep it warm for 12 hours; take it out after cooling to room temperature with the furnace, and perform the third grinding. The obtained samples were raised to 1200°C at a rate of 2°C/min, held for 12 hours, taken out and ground to obtain Gd _2.94 BW _0.60 O ₉ :Eu _0.06 , Mo _0.40 samples.

The Gd _2.94 BW _0.60 O ₉ : Eu _0.06 , Mo _0.40 powder prepared in this example is a pure phase of hexagonal Gd ₃ BWO ₉ . Its excitation and emission spectra are the same as Example 1, but the intensity is all enhanced than Example 1. The emission intensity basically does not change with temperature within 200°C, and the phosphor has excellent thermal stability of luminescence.

Claims (6)

1. A near-ultraviolet excited molybdenum tungsten borate red phosphor, characterized in that, with Gd ₃ BW _1-x Mo _x O ₉ as the matrix, with rare earth ions Eu ³⁺ as the active ion, the chemical composition is Gd _{3 -y} BW _1-x Mo _x O ₉ : Eu ³⁺ _y , where 0.15≤x≤0.4, 0.06≤y≤3. 2. the preparation method of the molybdenum tungsten borate red fluorescent powder excited by near ultraviolet light of claim 1 is characterized in that comprising the following steps: (1) The chemical composition of molybdenum tungsten borate red phosphor excited by near ultraviolet is Gd _3-y BW _1-x Mo _x O ₉ : Eu ³⁺ _y , where 0.15≤x≤0.4,0.06≤y≤3 For the stoichiometric ratio of each element, weigh the corresponding raw materials Gd ₂ O ₃ , H ₃ BO ₃ , WO ₃ , Mo ₂ O ₃ , Eu ₂ O ₃ , mix the raw materials and grind them evenly in an agate mortar to obtain the precursor body mixture (2) Place the precursor mixture in a temperature-programmed box-type resistance furnace for the first sintering at a temperature of 500°C to 600°C, and cool the sintered material to room temperature with the furnace, then take it out and grind it; then grind the The material is sintered for the second time at 1000-1100°C, cooled to room temperature with the furnace, and then taken out for grinding; then the ground material is sintered for the third time at 1150-1250°C, cooled to room temperature with the furnace, taken out for grinding , to obtain molybdenum tungsten borate red phosphor excited by near ultraviolet light. 3. The method for preparing the molybdenum tungsten borate red phosphor excited by near-ultraviolet according to claim 2, characterized in that 0.15≤x≤0.3. 4. according to the preparation method of the molybdenum tungsten borate red fluorescent powder excited by the described near-ultraviolet of claim 2, it is characterized in that, described first sintering is that precursor mixture is placed in the temperature-programmed box-type resistance furnace, with Heat up to 500-600°C at a rate of 1°C/min-3°C/min, and keep warm for 4-6 hours. 5. according to the preparation method of the molybdenum tungsten borate red fluorescent powder excited by the described near-ultraviolet of claim 2, it is characterized in that, described second sintering is that the material after grinding is placed in the temperature-programmed box-type resistance furnace, Raise the temperature to 1000-1100°C at a rate of 1°C/min-3°C/min, and keep it warm for 10-12 hours. 6. according to the preparation method of the molybdenum tungsten borate red phosphor excited by the described near-ultraviolet of claim 2, it is characterized in that, described third sintering is that the material after grinding is placed in the temperature-programmed box-type resistance furnace, Raise the temperature to 1150-1250°C at a rate of 1°C/min-3°C/min, and keep it warm for 10-12 hours.

Images