Department of Fundamental Natural Science, Okayama University of Science
Abstract
Studies on formation, thermal reaction and lattice dimensions of solid solutions in the system akermanite (Ca_2MgSi_2O_7)-hardystonite (Ca_2ZnSi_2O_7) have been carried out by DTA and X-ray powder diffraction on the products which were prepared by solid-state reaction using CaCO_3,MgO, ZnO and SiO_2 as starting materials. Åkermanite and hardystonite were preferably synthesized with double heatings at 1,330℃ and 1,250℃, respectively. The solid solutions were done at the intermediate temperatures in proportion to Mg/Zn of solid solutions. From akermanite to hardystonite, the melting points changed from 1,462℃ to 1,432℃ with approximately linear line. Further, the unit tetragonal cell constants, a_0 and c_0,changed linearly from 7.8328 and 5.0081 (Å) to 7.8250 and 5.0166 (Å), respectively. It is concluded that the solid solutions in the system akermanite-hardystonite form a complete series of solid solution by isomorphous replacement of Mg by Zn
