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• 作者：S. Belaaouad ; A. Charaf ; K. El Kababi ; M. Radid
• 关键词：Cyclotriphosphate ; Chemical preparation ; Infrared spectroscopy ; Thermogravimetric and differential analyses (TGA– ; DTA) ; X-ray diffraction ; Crystallographic characterization ; Thermodynamic properties
• 刊名：Journal of Alloys and Compounds
• 出版年：2009
• 出版时间：22 January 2009
• 年：2009
• 卷：468
• 期：1-2
• 页码：270-274
• 全文大小：498 K

文摘

Strontium and potassium cyclotriphosphate trihydrate, SrKP₃O₉·3H₂O, was prepared by ion-exchange resin. It crystallizes in the orthorhombic system Pnma, Z = 4 with the following unit-cell dimensions a = 9.082(2)Å, b = 8.133(2)Å, c = 15.009(2)Å and V = 1108.6(1)ų. This salt is isotypic of SrRbP₃O₉·3H₂O and SrNH₄P₃O₉·3H₂O whose crystal structure is determined by X-ray diffraction. Its thermal behavior is studied, between 25 and 800 °C, by infrared spectrometry, X-ray diffraction, thermal analyses TGA and DTA. SrKP₃O₉·3H₂O leads, between 250 and 350 °C, to the corresponding anhydrous phase, SrKP₃O₉. This new phase is characterized crystallographically as isotype of SrRbP₃O₉. The calcination, between 400 and 650 °C, leads to a mixture of SrK₂P₄O₁₂ crystallized and β[Sr(PO₃)₂] amorphous phase in X-ray diffraction. This mixture is stable until its melting point at 696 °C of SrK₂P₄O₁₂. The kinetic characteristics of the dehydration of SrKP₃O₉·3H₂O are determined. The vibrational spectrum of SrKP₃O₉·3H₂O is examined and interpreted, in the domain of the valency frequencies, on the basis of the crystalline structure of its isotypic compounds SrM^IP₃O₉·3H₂O (M^I = Rb⁺, Tl⁺) whose cycle has the site symmetry Cs. This infrared study is also made in the light of our results of the calculation of the IR frequencies and the successive isotopic substitutions of the equivalent atoms (3P, 3Oi and 6Oe belonging to the P₃Oi₃Oe₆ ring) of the P₃O₉³⁻ cycle with symmetry Cs.