Bi 2O 3–TiO 2 binary phase diagram study for TSSG pulling of Bi 12TiO 20 single crystals

Abstract

A substantial phase diagram in the hypo-peritectic region of Bi 12TiO 20 (BTO) was evaluated experimentally from lattice constant measurements of both BTO in ceramics with different TiO 2 contents and single crystals grown from different Bi 2O 3-rich solutions by a top-seeded solution growth (TSSG) method. There exists a solid-solution region with the retrograde solidus curve, of which the turning point lies around 13.85 mol% TiO 2, corresponding to a 9.0 mol% TiO 2 solution. From the 8.0–10.0 mol% TiO 2 solutions, the standard deviation of lattice constant was less than 1×10 −4 Å, indicating a very high reproducibility of the crystal composition. This result is the first proof of the existence of the retrograde solid-solution region in peritectic melting compounds.