α-Ca_3(PO_4)_2-Ba(H_2PO_4)_2溶液の固-液反応と新化合物BaHPO_4・CaHPO_4・H_2Oの生成

概要

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The solid-liquid reaction of α-Ca_3(PO_4)_2 and Ba(H_2PO_4)_2 solution proceeds to successively precipitate BaHPO_4, "X" phase and DCPD(CaHPO_4・2H_2O), depending on the sluggish dissolution of α-Ca_3(PO_4)_2. The process experiences three exothermal flows accompanying a three-step decrease in electric conductivity. Chemical analysis of the liquid phase together with X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM) of the residue were conducted to clarify the reaction mechanism. As a result a suitable method for isolating the new compound "X" was examined. The "X" phase was isolated, for example, by stirring a suspension composed of 0.6 g α-TCP and a mixed solution, 500 ml of 14.2 mmol・dm^<-3> Ba(H_2PO_4)_2(aq) and 300 ml of 15.0 mol・dm^<-3> Ca(H_2PO_4)_2(aq), for several hours. The chemical formula of the "X" phase was BaHPO_4・CaHPO_4・H_2O and its crystal structure was monoclinic with unit-cell parameters, a=1.0656 nm, b=0.7802 nm, c=0.9605 nm and β=104.26°.
社団法人日本セラミックス協会の論文
2000-06-01