RU2004566C1 - Inorganic luminophore with radiation in ir-range of spectrum - Google Patents

Abstract

SUMMARY OF THE INVENTION; the qualitatively-quantitative composition of the phosphor corresponds to the chemical formula K Y Nd Yb F, where 0.001s xs 0.150; 0.02s ys 0.20. With a mixture of yttrium neodymium oxides, ytterbi is poured with a drop of fluoride solution. heated in a sealed pressure vessel to 500 ° C; C and can withstand 100 hours. Quantum energy transfer efficiency t 0.67-0.97. 5 id 1 tabd

Description

The invention relates to phosphors based on crystalline phosphors with neodymium and ytterbium, and is intended to convert visible radiation into radiation in the PC spectral region.

PC phosphors are used in LEDs for fiber optic communication and in lasers for medical purposes. Recently, IR phosphors have been used in gel energy in photovoltaic devices based on luminescent solar concentrators (LSCC). For the effective operation of the LSC, it is very important to match the spectral composition of the phosphor radiation with the region of maximum sensitivity of the silicon solar cell (about 90 nm).

Germanate and tellurite glasses are known, activated by neodymium and ytterby ions, used in solar energy collectors 1. In 2, materials for LSC are described: lithium-lanthanum-phosphate glasses activated by neodymium and ytterby ions, the energy conversion coefficient in these glasses reaches 80%.

In borate glasses 3, the energy transfer coefficient reaches 87%. In fluid glasses activated by neodymium and ytterby 4 ions, the transmission coefficient reaches 79.4%.

Closest to the invention in terms of quality composition is a phosphor based on lithium-yttrium fluoride activated by neodymium and ytterbium LIYF4: Nd3 + YB3 + 5. The luminescence intensity of 9944 Fs / 2-Yb increases significantly with neodymium sensitization. In the Nd absorption spectrum, the most intense lines are: 740, 800 and 880 nm, 961.5 nm lines are observed in the ytterbi absorption spectrum, and 949.3 are weaker; 974.6; 981.6; 995.3 and 1019.9 nm.

The lifetime of neodymium luminescence from the Pz / 2 level decreases from T0 500 μs (without ytterby coactivator) to g-210 μs with the introduction of Yb. Therefore, energy transfer is non-radiative.

The luminescence lifetime of ytterbi from the Fs / 2 level does not change with the introduction of neodymium and is equal to 2500 μs. Consequently, there is no reverse energy transfer from ytterby to neodymium.

Energy transfer rate R

- 2.8. Quantum Effective- i ID

energy transfer capacity / tr 1 - - 0.58,

which determines the low intensity of infrared lignaminescence.

An object of the invention is to increase the luminescence intensity by increasing the quantum energy transfer efficiency.

The goal is achieved in that

The phosphor based on neodymium and ytterbi fluorides additionally contains potassium fluoride at a ratio of the starting components satisfying the chemical formula

K2Yi-x-y Yby / NdxF5,

where 0.001 x 0.150; 0.02 at 0.20.

At the indicated ratio of components, a highly efficient energy conversion is observed due to the high probability of nonradiative transitions in a given fluoride crystalline matrix. The crystal structure of this phosphor is a stacking of endless in the 001 direction radicals constructed from UR}} polyhedra, which is in good agreement with the fibrous nature and prismatic habit of K2YF6 crystals 6. The preparation of the phosphor is based on the method of hydrothermal synthesis. For this, a mechanical mixture comprising yttrium oxide, neodymium oxide and ytterby oxide, in

10 g are placed in a pressure vessel lined with a 30 cm copper insert and poured with a 28 mol% potassium fluoride solution in an amount of 18 cm. The pressure vessel is sealed, injected, heated to a temperature of 500 ° C and held at this temperature for 100 hours. Then, the NOC is cooled to room temperature, the pressure vessel is opened and removed. In the described manner, phosphors were obtained, the composition of which is given in the table.

The phase composition of the obtained product was controlled by x-ray phase

analysis. In all cases, only the formation of compounds with a set of X-ray reflexes, which are induced in a rhombic syngony with unit cell parameters, was recorded:, 76;

, 60; , 25 A, i.e. compounds corresponding to the compositions

K2Yi-x-yYbyNdxF5.

Figure 1 presents the luminescence spectra of neodymium in crystals of double potassium fluoride-yttrium, corresponding to the composition

K2Yo.9Ndo.iF5 (1) and K2Yo.7Ndo, iYbo.2F5. (2)

Figure 2 - luminescence spectra of a concentrated series of crystals of KzYi-x-yYbyNdx at x 0.1; 0.02 (1); x 0.1; y 0.05 (2); x 0.1; at 0.1 (3); x 0.1; at 0.2 (4). Figure 3 shows the luminescence excitation spectra of neodymium and ytterbi in potassium-yttrium double fluoride crystals. Figure 4 shows the dependence of the neodymium lifetime on its concentration in crystals.

Luminescence spectra and luminescence excitation spectra were obtained upon excitation with a MKGN-150 halogen lamp using MDR-23 and MDR-2 monochromators with registration using a FEU-79 and FEU-62 with a KS-18 or KS-19 light filter. The received information was recorded and processed using microZM Electronics DZ-28.

. In the luminescence spectra of neodymium in crystals of potassium double-fluoride double fluorides at y 0, x 0.1, two intense groups of lines with maxima of 980 v are observed. 1046 nm, corresponding to Pz / 2 - 1o / 2 and 4Pz / 2 - 41 c / 2 transitions. In crystals activated simultaneously by neodymium and ytterby ions, the luminescence of neodymium ions is quenched, intense luminescence of ytterby is observed with a maximum of 968 nm, transition 2P5 / 12 - 2fi / 12 (Fig. 1, spectrum 2). The luminescence excitation spectra of neodymium and ytterby coincide, which indicates the transfer from neodymium ions to ytterbium (Fig. 3).

The coefficient of non-radiative transfer of excitation energy (s) between these ions is calculated by the formula

- - &

where T0 is the decay time of the luminescence of neodymium ions in crystals of potassium-yttrium double fluorides activated by neodymium; and ta is the decay time of neodymium luminescence in the presence of ytterby. The luminescence kinetics of neodymium ions in potassium-yttrium fluoride crystals was recorded on a two-coordinate recorder, then it was logarithmized and processed using the least squares method with a computer, and it was also recorded on a chart tape using a plotter. The lifetime of neodymium in crystals was also determined directly from the oscilloscope screen. The dependence of m on N is shown in Fig. 4. The relative luminescence intensity of ytterby in KzYi-x-yNdxYbyFs, where 0.001 x 0.150; 0.02 at 0.20, measured relative to the sample

5

10 15

20 25 0

5

0

5 0 5

Al3Ndo, 9Ybo.i (B03) 4 using a rocker. Samples of exactly the same shape and size were excited by the light of a halogen lamp through an SZS filter, ytterby luminescence through a KS-19 filter was recorded using silicon photoelectronic converters with the Shch4311 device.

The found values of the transfer coefficients of the excitation energy from neodymium to ytterbium in the crystals of the claimed phosphor, relative luminescence intensities of the obtained samples relative to the base object AlaNdo.gYbo.iCBOa) are given in the table.

Figure 5 shows the dependence of the coefficient of non-radiative transfer of excitation energy (t / u) as a function of the neodymium concentration of 0.001 x 0.150 at a constant ytterby concentration (at 0.2) (curve a) and the dependence / tr with a change in the ytterby concentration from 0, 02 to 0.20 with a constant concentration of neodymium (x 0.1) (curve b); curve c - for the prototype: LiYRi: 2% NcTh + 2% Yb3 +.

Fig. 5a shows that for all samples, 0.001 x 0.1, with 0.2 tr of the phosphor higher than that of the prototype. From FIG. B, it follows that the tjir for the phosphor is higher than that of the prototype at 0.02 at 0.20, x 0.1.

Therefore, it can be argued that a phosphor satisfying the chemical formula K2Yi-x-yYbyNdxF5, where 0.001 x 0.150 and 0.02 at 0.20, has an increased coefficient compared to the prototype and a higher luminescence intensity.

The limitations of ytterbi and neodymium are due to the following reasons; with an increase in the neodymium content above x 0.15, ytterbium above O, 2, the quality of single crystals deteriorates (cracking, turbidity, formation of stitches, etc.). As the content of both the donor, x 0.001, and the acceptor (at 0.02) decreases, the absolute luminescence intensity decreases.

(56) 1. Relsfeld R. and Kalisaky J. Nd3 and Yb germanate and tellurlte glasses for fluorescent solar energy collectors. Chem. Phys. Lett. 1981, v. 80. N 1. p. 178-183.

2. Parent C., Lurln C, Le Flem J. and Hagenmuller Nd3 + - Yb34 energy transfer In glasses with composition close to LIZnP40i2 metaphosphate (Ln-La, Nd, Yb). J, of Luminescense. 1986, v. 36. p. 49-55.

3. Lurln S., Parent S. and Le Flem C. Borate glasses with of hlght Nd3 - Yb3 energy transfer probability. J. of Less. Common metals, 1985, v. 112, p. 91-95.

4. Ejal M., Relsfeld R. Energy transfer between Neodymium (III) ans Ytterbium (III) In transition - metal f luoride (TMPC) glasses. Chem. Phys. Letters. 1986, v. 129. N 6. p. 550-556.

5.Miller I.E. Sharp E.I. Oprical properties and energy transfer In LIYRj; Nd34 Yb3b, J. Appl. Phys. 1970.v, 41. p. 4718-4722.

6.Kharitonov Yu.Yu. et al. Crystal structure of potassium yttrofluoride // Crystallography, 1983, vol. 28, issue 5, pp. 1031-1032.

7. For wka FRG Mg 2903073, cl. S 09 K 11/46, 1981.

Claims (1)

SUMMARY OF THE INVENTION INORGANIC LUMINOPHOR WITH IR RADIATION OF THE SPECTRA based on fluoride of an element of group I, containing yttrium fluoride and activated by neodymium and ytterbium, characterized in that, in order to increase the luminescence intensity by increasing quantum efficiency of energy transfer, it additionally contains potassium fluoride as an element of group I at a ratio of components satisfying the chemical formula Ndx Yby F5, where 0.001 x 0.150; 0.02 at 0.20. Eun T  uuuofc 99SW05  "01 t DOfit 60 wnb Yu Opibl O WH (2f 006 008 fr jhfl ot Si. Q ( PIBL O "with W- i№ , . QQL 009 005 1 NSHO Ј 993YOZ | 1 se "X YU about Ј  & 10