Synthesis and characterization of phosphates in the pseudo-ternary melted systems Cs2O-P2O5-MIIO (MII – alkaline earth)

✍ Scribed by I. V. Zatovsky; N. Yu. Strutynska; N. S. Slobodyanik; V. N. Baumer; O. V. Shishkin

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 225 KB
• Volume: 43
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.200711077

✦ Synopsis

The crystallization of alkali-earth phosphates in the melts of Cs 2 O-P 2 O 5 -M II O (M II -Ca, Sr, Ba) pseudoternary systems have been investigated at various Cs/P molar ratios and at fixed value of M II /P equal to 0.15. Type of the phosphate which crystallizes in melts depends on the Cs/P initial ratio. Crystallization fields of CsM II P 3 O 9 , M II 2 P 2 O 7 and Cs 2 M II P 2 O 7 were briefly investigated and characterized. The new diphosphate Cs 2 CaP 2 O 7 has been obtained and investigated by the single crystal and powder X-ray diffraction and FTIRspectroscopy. It crystallizes in C 2/m space group, with the following parameters of the monoclinic cell: a = 10.261(2), b = 5.9316( 12), c = 7.2404(14) Å, β = 118.54(3)°. The architecture of [CaP 2 O 7 ] 2-anionic sublattice, which is built up from [CaO 6 ] octahedra and [Р 2 О 7 ] bitetrahedra, interlinked via the common oxygen vertices, gives rise to formation of hexagonal tunnels along crystallographic direction b, where caesium atoms are located. One of the most remarkable features of the structure is specific positional disorder of the diphosphate group, which is connected with the existence of two equiprobable half-occupied sites of the bridging oxygen.