阅读说明：本技术 一种高热稳定性荧光粉 (High-thermal-stability fluorescent powder ) 是由 苟婧 陈雅利 俞斌勋 于 2019-09-02 设计创作，主要内容包括：本发明公开了一种高热稳定性荧光粉,该荧光粉的分子式为Sr<Sub>8</Sub>Zn<Sub>0.88-x</Sub>Sc(PO<Sub>4</Sub>)<Sub>7</Sub>:12％Tb<Sup>3+</Sup>,式中0.4≤x≤0.8。本发明通过改变基质中Zn<Sup>2+</Sup>比例,在Tb<Sup>3+</Sup>浓度不变的条件下,x的增加将更多的V”<Sub>Zn</Sub>和V<Sup>··</Sup><Sub>O</Sub>缺陷引入荧光粉中。在370nm近紫外光激发下,由于V”<Sub>Zn</Sub>+V<Sup>··</Sup><Sub>O</Sub>缺陷簇中浅陷阱与Tb<Sup>3+</Sup>能级之间的能量转移,Tb<Sup>3+</Sup>的<Sup>5</Sup>D<Sub>3</Sub>→<Sup>7</Sup>F<Sub>J</Sub>和<Sup>5</Sup>D<Sub>4</Sub>→<Sup>7</Sup>F<Sub>J</Sub>发射峰均随x增大而增强,当x＝0.4时,荧光粉的发光强度可以达到x＝0的1.4倍。由于在温度升高过程中V”<Sub>Zn</Sub>+V<Sup>··</Sup><Sub>O</Sub>缺陷簇中能够释放不同深度陷阱捕获的电子,弥补了荧光粉在高温下的热猝灭行为。当温度达到200℃时,x＝0.8荧光粉的发光强度可以达到室温的1.22倍,而x＝0荧光粉的发光强度是室温的1.03倍。(The invention discloses a high-thermal stability fluorescent powder, the molecular formula of which is Sr 8 Zn 0.88‑x Sc(PO 4 ) 7 :12％Tb 3+ Wherein x is more than or equal to 0.4 and less than or equal to 0.8. The invention changes Zn in the matrix 2+ Ratio at Tb 3+ At constant concentration, the increase in x will be more V " Zn And V ·· O Defects are introduced into the phosphor. Excited by 370nm near ultraviolet light, due to V " Zn +V ·· O Shallow traps and Tb in defective clusters 3+ Energy transfer between energy levels, Tb 3+ Is/are as follows 5 D 3 → 7 F J And 5 D 4 → 7 F J the emission peak increases with the increase of x, and when x is 0.4, the luminous intensity of the fluorescent powder can reach 1.4 times of x 0. Since during the temperature rise V " Zn +V ·· O Electrons captured by traps at different depths can be released in the defect clusters, and the thermal quenching behavior of the fluorescent powder at high temperature is compensated. When the temperature reaches 200 ℃, x ═The 0.8 phosphor can have an emission intensity of 1.22 times the room temperature, while the x-0 phosphor has an emission intensity of 1.03 times the room temperature.)

1. A high thermal stability phosphor, characterized by: the molecular formula of the fluorescent powder is Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺Wherein x is more than or equal to 0.4 and less than or equal to 0.8; the preparation method comprises the following steps: according to Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺The Sr (NO) with the purity of more than 98 percent₃)₂、ZnO、(NH₄)₂HPO₄、Sc₂O₃And Tb₄O₇Uniformly mixing, firstly preserving heat for 3-5 hours at 850-950 ℃, then preserving heat for 10-12 hours at 1200-1300 ℃, and naturally cooling to room temperature.

2. A phosphor of claim 1 having high thermal stability, characterized in that: in the formula, x is 0.8.

3. A phosphor with high thermal stability according to claim 1 or 2, characterized in that the phosphor is prepared by the following method: according to Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺The stoichiometric ratio of (A) is that Sr (NO) with the purity of 99.9 percent is added₃)₂ZnO with purity of 99.99 percent and (NH) with purity of 98.5 percent₄)₂HPO₄Sc of 99.99% purity₂O₃And Tb with a purity of 99.99%₄O₇Mixing, maintaining at 900 deg.C for 4 hr, maintaining at 1250 deg.C for 11 hr, and naturally cooling to room temperature.

Technical Field

The invention belongs to the technical field of fluorescent materials, and particularly relates to a fluorescent powder with high thermal stability.

Background

When the high-power LED is used, the working temperature is very high, and the fluorescent powder can generate thermal quenching when emitting light, namely, the fluorescent powder is reduced along with the temperature rise. Therefore, for high-power WLEDs (white-light-emitting diodes), the development of phosphors with excellent thermal stability at high operating temperatures is the bottleneck of the current commercial high-power WLEDs. At present, commercial fluorescent powder can generate a quenching phenomenon of fluorescence at a high working temperature, and the working temperature of 120 ℃ is a temperature limit at which high-efficiency output efficiency can be realized by high-power WLED. Therefore, how to design and develop new phosphors with high luminous intensity and high thermal stability is a great challenge to realize commercialization of high-power WLEDs.

The invention patent with publication number CN 108893113A discloses a chromaticity-adjustable high-thermal-stability fluorescent powder, wherein the molecular formula is Sr₈Zn_0.88Sc(PO₄)₇:12％Tb³⁺The phosphor of (1) exhibits the most excellent thermal stability, which is measured at 75 ℃ and 175 ℃,⁵D₃→⁷F_Jthe emission intensity of the emission peak was increased to 1.28 and 1.19 times at room temperature,⁵D₄→⁷F_Jthe emission intensity of the emission peak was increased to 1.19 and 1.18 times at room temperature, respectively. However, when the temperature exceeds 175 ℃, the luminous intensity begins to decrease, and particularly when the temperature reaches 250 ℃, the luminous intensity already decreases below the room-temperature luminous intensity. For high power LEDs, this drawback still remains to be improved.

Disclosure of Invention

The invention aims to provide a fluorescent powder with higher luminous intensity and high thermal stability under the excitation of near ultraviolet light.

In view of the above, the molecular formula of the phosphor with high thermal stability of the present invention is Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺Wherein x is 0.4. ltoreq. x.ltoreq.0.8, preferably 0.8.

The preparation method of the fluorescent powder with high thermal stability comprises the following steps: according to Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺The Sr (NO) with the purity of more than 98 percent₃)₂、ZnO、(NH₄)₂HPO₄、Sc₂O₃And Tb₄O₇The mixture is evenly mixed and stirred,preserving heat for 3-5 hours at 850-950 ℃, preserving heat for 10-12 hours at 1200-1300 ℃, and naturally cooling to room temperature.

In the above method for producing a phosphor having high thermal stability, Sr is preferable₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺The stoichiometric ratio of (A) is that Sr (NO) with the purity of 99.9 percent is added₃)₂ZnO with purity of 99.99 percent and NH with purity of 98.5 percent₄)₂HPO₄Sc of 99.99% purity₂O₃And Tb with a purity of 99.99%₄O₇Mixing, maintaining at 900 deg.C for 4 hr, maintaining at 1250 deg.C for 11 hr, and naturally cooling to room temperature.

The invention is realized by adding Sr₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺Changing Zn in phosphor²⁺Ion ratio, more V "_ZnAnd V_··ODefects are introduced into the fluorescent powder, under the excitation of near ultraviolet light 370nm, defect clusters are used as traps to capture electrons, and the electrons are transferred to Tb under certain thermal disturbance³⁺Of ions⁵D₃Energy level, further through⁵D₃Energy level transfer to⁵D₄Energy level, thereby realizing thermal stability of the fluorescent powder at high working temperature.

At room temperature when Sr is₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺The fluorescent powder is excited by 370nm near ultraviolet light, Tb³⁺Is/are as follows⁵D₃→⁷F_JAnd⁵D₄→⁷F_Jthe emission of (a) increases with increasing x. Thus, Tb is enhanced³⁺It is not the intrinsic nature of the f-f transition that is emitted, which should be associated with increased V "_ZnThe defect is relevant. Except for Tb³⁺Is/are as follows⁵D₃→⁷F_JAnd⁵D₄→⁷F_Jbesides the emission, the 400-405 nm emission area is also affected by the increase of x. V'_ZnThe defect increase can enhance the emission between 400-405 nm. Therefore, the emission band between 400-405 nm is attributed to V "_Zn+V¨_ODefective cluster captureReleasing carriers. Therefore, Tb³⁺Is/are as follows⁵D₃→⁷F_JAnd⁵D₄→⁷F_Jthe enhancement of emission should be due to shallow V "_Zn+V¨_ODefect cluster trap and Tb³⁺Energy transfer between energy levels.

When the working temperature is increased, the Sr is excited by the near ultraviolet light₈Zn_0.88-xSc(PO₄)₇:12％Tb³⁺During fluorescent powder, the trap with deeper energy level transfers the captured electrons to Tb under thermal disturbance³⁺Of ions⁵D₃Energy level, thereby making up for high temperature⁵D₃→⁷F_JAnd⁵D₄→⁷F_Jthe thermal quenching phenomenon of an emission peak realizes the zero thermal quenching behavior of the fluorescent powder at high temperature.

Drawings

FIG. 1 shows emission spectra of samples prepared in examples 1 to 3 and comparative example 1 under excitation of 370nm near ultraviolet light at room temperature.

FIG. 2 is a schematic diagram showing the relationship between the integrated intensity of the emission spectrum and the doping concentration x under the excitation of 370nm near ultraviolet light at room temperature for samples prepared in examples 1 to 3 and comparative example 1.

FIG. 3 is a luminescence thermal quenching spectrum with increasing temperature under 370nm near UV excitation for the sample prepared in comparative example 1.

FIG. 4 is a luminescence thermal quenching spectrum with increasing temperature under 370nm near UV excitation for samples prepared in example 1.

FIG. 5 is a luminescence thermal quenching spectrum with increasing temperature under 370nm near UV excitation for samples prepared in example 3.

FIG. 6 is a graph showing the integrated area of the emission peak at 400 to 650nm as the temperature rises for the sample prepared in example 3, as a function of temperature.

Detailed Description

The invention will be further described in detail with reference to the following figures and examples, but the scope of the invention is not limited to these examples.