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Abstract: The interaction of TiN with Na2O–K2O–P2O5 melts was investigated at (Na+K)/P molar ratios of 0.9, 1.0, and 1.2 and at Na/K molar ratios of 1.0 and 2.0. Interactions in the system led to the loss of nitrogen and the partial loss of phosphorus and resulted in the formation of KTiP2O7 and langbeinite‐type K2−xNaxTi2(PO4)3 (x=0.22–0.26) solid solutions over the temperature range of 1173 to 1053 K. The phase compositions of the obtained samples were determined by using X‐ray diffraction (including Rietveld refinement), scanning electron microscopy (using energy‐dispersive X‐ray spectroscopy and element mapping), FTIR spectroscopy, and thermogravimetric analysis/differential thermal analysis. K1.75Na0.25Ti2(PO4)3 was characterized by single‐crystal X‐ray diffraction [P213 space group, a=9.851(5) Å]. The 3D framework is built up by TiO6 octahedra and PO4 tetrahedra sharing all the oxygen vertices with the formation of cavities occupied by K(Na) cations. Only one of the two crystallographically inequivalent potassium sites is partially substituted by sodium, and this was confirmed by calculating the bond‐valence sum. The thermodynamic stability of K1.75Na0.25Ti2(PO4)3 crystals and the preferable occupation sites of NaK cationic substitutions were investigated by DFT‐based electronic structure calculations performed by the plane‐wave pseudopotential method. [ABSTRACT FROM AUTHOR]

Solid solutions KTi1-XHfXOPO4 (х = 0.008 - 0.107) possessing the KTiOPO4 structure, have been synthesized in molten system K2O-P2O5-TiO2-HfF4. The crystal growth experiment of Hf-doped KTP crystal has been reported. The X-ray powder diffraction data and chemical analysis are also presented. It has been shown that KTiOPO4 crystal structure slightly changes when Hf incorporates into the framework. Transmission/absorption spectra of KTi0.974Hf0.026OPO4 crystals have been recorded. The incorporation of Hf ions shifts the optical absorption edge in the UV-visible spectrum towards the long-wavelength region with absorption near 387 nm. [ABSTRACT FROM AUTHOR]

Abstract: The crystallization of complex phosphates from the melts of Cs2O–P2O5–CaO–M III 2O3 (M III—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/М III=1. The fields of crystallization of CsCaP3O9, β-Ca2P2O7, Cs2CaP2O7, Cs3CaFe(P2O7)2, Ca9 M III(PO4)7 (M III—Fe, Cr), Cs0.63Ca9.63Fe0.37(PO4)7 and CsCa10(PO4)7 were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa10(PO4)7 and Cs0.63Ca9.63Fe0.37(PO4)7 have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4)Å, с=37.2283(19) and 37.2405(17)Å, respectively. [Copyright &y& Elsevier]

Abstract: A new potassium bismuth phosphate-molybdate K2Bi(PO4)(MoO4) has been synthesized by the flux method and characterized by single-crystal and powder X-ray diffraction, IR spectroscopic studies. The compound crystallizes in the orthorhombic system with the space group Ibca and the cell parameters: a=19.7037(10), b=12.4752(10), c=7.0261(10). This phase exhibits an original layered structure, in which the [Bi(PO4)(MoO4)]∞ layers consist of [Bi2Mo2O18]∞ chains linked through single PO4 tetrahedra. The K+ cations interleaved between these layers exhibit a monocapped distorted cubic coordination. [Copyright &y& Elsevier]

The particularities of the chemical interaction in systems MIPO3 -MIIO(or Mn2O3)- MICl ( MI - Na, K; MII - Mg, Co, Ni, Zn) have been investigated at the temperature 1073 K and molar ratios P/ Mx = 1 or 2 and MICl/( MIPO3 + MIIO(or Mn2O3)) = 30. The conditions of formation of complex phosphates MІMIIPO4 and Na4Ni3(PO4)2P2O7 have been found. Influences of the nature of alkali and bivalent metals on the products composition were discussed. The advantages of chloride melts using (synthesis time reduction and temperature reducing) for preparing of complex phosphates were shown. The synthesized compounds have been characterized using the powder X-ray diffraction, Fourier transform infrared and diffuse reflectance spectroscopies. [ABSTRACT FROM AUTHOR]