Microscopic PL spectrometer---Detection of phosphors

Phosphor Sr2.99-xCax(P04)2: Eu2+0.01 (x=0.6, 0.7, 0.8, 0.9, 1.0) PL spectrum

Oxygen (nitrogen) phosphor powder materials have received extensive attention in the field of solid state light due to their high luminous efficiency, effective excitation by visible light, high stability and environmental friendliness. Among them, rare earth doped phosphors have good application prospects due to their high luminescence intensity, high quantum efficiency and excellent thermal stability. The Eu (Eu) element has two valence states of Eu ²⁺ and Eu ³⁺ in the compound. The emission peak of Eu ²⁺ is susceptible to the crystal field, that is, the change of the matrix or the impurity material (concentration, element, etc.), the intensity of the emission peak will change, and the emission center will be red-shifted or blue-shifted; Eu ³⁺ The emission peak is determined by itself, and is sharp and the peak position is not affected by the crystal field.

Eu ²⁺ has a 4f-5d transition allowed by spin, and exhibits broadband absorption and emission, making it the most commonly used rare earth activator in phosphors. Figure 1 is a PL spectrum of Sr _2.99-x Ca _x (P04) ₂ :Eu ²⁺ _0.01 (x=0.6,0.7,0.8,0.9,1.0) phosphor. The test instrument is a Flex One display independently developed by the company. The micro-PL system uses a 325 nm He-Cd laser as an excitation source. It can be seen from the analysis of Fig. 1 that the reduction of Eu ³⁺ in the phosphor is incomplete, and Eu ²⁺ and Eu ³⁺ are simultaneously present in the phosphor.

Spectral analysis:
It can be seen from the figure that as the content of Sr decreases, the content of Ca increases, and the luminescence intensity of the 4f ⁶ 5d ¹ →4f ⁷ yellow light band (luminous peak at 532 nm) corresponding to Eu ²⁺ increases gradually, but There are luminescence peaks of Eu ³⁺ . The luminescence peak of Eu ³⁺ mainly includes: 578 nm corresponds to ⁵ D ₀ → ⁷ F ₀ , 590 nm and 594 nm corresponds to ⁵ D ₀ → ⁷ F ₁ , and 616 nm and 624.5 nm correspond to ⁵ D ₀ → ⁷ F ₂ 650 nm or so corresponds to ⁵ D ₀ → ⁷ F ₃ , and 700 nm corresponds to ⁵ D ₀ → ⁷ F ₄ .

Micro PL system Flex One

It is suitable for the detection of phosphors in scientific research and production: the ultra-high resolution of the system greatly improves the detection ability of the characteristic peaks of the phosphors, such as the shift of the rare earth elements to the characteristic peaks and peaks. The ultra-high sensitivity of the system greatly improves the detection of the influence of elemental content on peak intensity. The system can be used to study the effects of changes in composition of different batches of phosphors on quality and monitoring.

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[Author]: Shi Guangli, Cai Hongtai, Applied Research and Development Department, Analytical Instrument Division [References: [1] Li Yongjin, Huang Yangbin, Liu Qun, et al. Near-ultraviolet excitation of Er ³⁺ /Eu ³⁺ co-doped BiOCl with color modulation Phosphors[J]. Acta Phys. Sin., 2015, 64(17): 177803-1-177803-6