フラックス法によるウォラストナイトの結晶成長

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Studies on crystal growth of wollastonite (β-CaSiO3) were attempted by slow cooling from NaCl flux.The solubility of CaSiO3 in NaCl was very low with 0.09 wt% at 1010°C and 0.42 wt% at 1190°C. The mixtures consisting of the 2-3 wt% of synthetic wollastonite in NaCl of 20-45g, in excess to its solubility, in the Pt crucible were soaked for 0-24 hours at 1080°-1200°C and then cooled to about 800°C with a rate of 5°C per hour.On crystal growth from above 1125°C, both crystals of pseudowollastonite (α-CaSiO3) and wollastonite were obtained, the former was stable above 1125°C and the latter was stable below 1125°C.The wollastonite crystals grown by a soaking at 1200°C for 24 hours were large in size and small by number, for they would have grown from only a few spontaneous nuclei on the upper wall of the crucible. For the soaking at 1150°C, it was found that they were small in size and large by number. These seemed to be formed from much nuclei from the unsolved residues which were excess to its solubility in the bottom of the crucible.The wollastonite crystals, needle-shaped as large as 6mm in length and 0.3mm in diameter, were grown along b-axis and they took usually single crystal and sometimes twinned crystal.
社団法人日本セラミックス協会の論文
1967-11-01