492 † We previously studied the phase formation in sulfu ric acid solutions of titanium subgroup element com pounds in the presence of alkali metal fluorides [1]. Under "mild" synthesis conditions, we isolated about a hundred of alkali metal fluorometallates and fluoro sulfate metallates, most of which were obtained for the first time. Investigation of a number of the compounds showed that some of them are characterized by intense X ray luminescence. X ray luminophores promising for practical applications are hexafluorozirconates M 2 Zr(Hf)F 6 (M = K, Rb, Cs) and also Rb 3 Zr 2 F 9 SO 4 ⋅ 2H 2 O [2, 3]. Two important results were obtained: on the one hand, the synthesized materials exhibit rela tively intense X ray luminescence over a wide wave length range, and on the other, it was found that the efficiency of the X ray luminescence efficiency can be enhanced and its spectrum and temporal characteris tics can be optimized by transforming some crystal lat tice defects to others, being X ray luminescence cen ters.
Phosphate zirconatesCsZr 2 (PO 4 ) 3 [4, card 34 0196], α Cs 2 Zr(PO 4 ) 2 [4, card 28 0356], and Cs 3 Zr 1.5 (PO 4 ) 3 [4, card 52 1181] are known. At low concentration of the phosphorus component, we isolated crystalline cesium fluorophosphate zirconate CsZrF 2 PO 4 ⋅ H 2 O and also amorphous oxofluorophosphate Cs 2 Zr 3 O 2 F 4 (PO 4 ) 2 ⋅ 3H 2 O and amorphous oxofluorophosphate nitrate CsZr 3 O 1.25 F 4 (PO 4 ) 2 (NO 3 ) 0.5 ⋅ 4.5H 2 O. The compound Cs 3 Zr 3 O 1.5 F 6 (PO 4 ) 2 ⋅ 3H 2 O was obtained, which forms in the crystalline or glassy state, depending on the con ditions. The formation of the compounds Cs 2 Zr 3 O 1.5 F 5 (PO 4 ) 2 ⋅ 2H 2 O, Cs 2 Zr 3 F 2 (PO 4 ) 4 ⋅ 4.5H 2 O, and Zr 3 O 4 (PO 4 ) 1.33 ⋅ 6H 2 O was established, which crys tallize only in mixtures with the known phases [5]. † Deceased.The system ZrO(NO 3 ) 2 -H 3 PO 4 -CsF-H 2 O was studied along the section at the molar ratio F/Zr = 2-5 at 2-5 wt % ZrO 2 . The initial substances were ZrO(NO 3 ) 2 ⋅ 2H 2 O and 85% H 3 PO 4 (both of analytical grade), and CsF (chemically pure). CsF was added while continuously stirring to ZrO(NO 3 ) 2 ⋅ 2H 2 O solu tions. After the mixtures became homogeneous, H 3 PO 4 was added to them. After keeping the obtained mixtures for 7-45 days, precipitates were filtered off, washed successively with water and alcohol, and dried in air. The ZrO 2 content in solution was calculated with the consideration of H 3 PO 4 before adding CsF. Phases in the precipitates were identified by X ray powder diffraction, crystal optical, thermal, elemen tal, and IR spectroscopic analyses. The X ray powder diffraction patterns were recorded with a DRF 2 instrument (graphite monochromator, CuK α radia tion). The crystal optical measurements were per formed using immersion liquids. The thermograms were recorded in air using a Pt-Pt/Rh thermocouple. The reference substance was calcined aluminum oxide. The weight loss was determined with a VT 1000 torsion balance at a heating rate of ~9 deg/min. The IR spectra in the frequen...
