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Etude du système KPO3Sm(PO3)3 et des phases polymorphiques de phosphates condensés KSm(PO3)4

1987; Elsevier BV; Volume: 69; Issue: 1 Linguagem: Inglês

10.1016/0022-4596(87)90002-8

1095-726X

M. Férid, Nejia Kbir Ariguib, Mélika Trabelsi,

Thermal and Kinetic Analysis

Abstract The KPO3Sm(PO3)3 system has been studied for the first time by μ-DTA, X-ray diffraction and IR spectroscopy. The only compound observed within the system was KSm(PO3)4 melting incongruently. An eutectic appears at 14 mole% Sm(PO3)3 at 937 K; the peritectic occurs at 1133 K; transition was observed at 717 K for KPO3. Preparation of single crystals leads to three monoclinic polymorphs. The KSm(PO3)4 polyphosphate belongs to the P21 space group with lattice parameters: a = 7.242(6) A, b = 8.37(4) A, c = 7.950(4) A, β = 91.96°(6), and Z = 2; it is isotypic with KNd(PO3)4. It melts at 1133 K. The tetrametaphosphate KSmP4O12 is isotypic with NH4NdP4O12; it crystallizes in the C2 c space group: a = 7.944(7) A, b = 12.41(1) A, c = 10.718(9) A, β = 110.38°(9), and Z = 4. It melts at 1145 K. The last polyphosphate KSm(PO3)4 belongs to the P2 1 c : a = 10.800(3) A, b = 9.015(4) A, c = 12.791(5) A, β = 128.43°(2), Z = 4; it is isotypic with TlNd(PO3)4. It melts at 1145 K. The chemical preparation, crystallographic data, and IR spectra for these compounds are given.