Flux Growth of Lead Titanozirconate Single Crystal Using Titanium and Zirconium Fluorides of Potassium and Lead Oxide as Starting Materials

Using titanium and zirconium fluorides of potassium and lead oxide as starting materials, the authors grew lead titanozirconate single crystals by the flux slow-cooling method. The results were as follows: (1) With composition of more than 50mol% of PbO, the range of growth of Pb (ZrxTi1-x)O3 single crystals was determined. (2) Within the maximum temperature range from 920°C to 1100°C, single crystals of lead titanate of 7.3×4.7×4.0mm in size, lead titanozirconate of 2.4×2.0×1.5mm and lead zirconate of 3.1×2.3×2.0mm were obtained. Their crystallinity was high so that it was more easy to obtain an individual single crystal than a granular mass produced from the oxide materials. (3) Assuming a reaction formula of the K2(ZrxTi1-x)F6-PbO system; the yield of lead titanate could be increased to 80% from 40% by adding 0.2mol of KOH according to the formula. (4) In the case of lead titanate, (a) there was a tendency that tabular and acicular crystals grew from oxide materials, whereas (b) square crystals were obtaind from fluoride materials. In addition, when the slow cooling rate changed from 8°C to 2°C/h, the obtained maximum individual single crystals were increased in size linearly from 0.05 to 0.55g. (5) The solid solution condition of zirconium in lead titanozirconate was good and crystals of just the same composition as the raw material were obtained. Owing to the use of a vessel of type (ii) for crystal growth, the flux evaporation was decreased to 15% from 40% of that by oxide materials. (6) In the case of lead zirconate, the yield was increased to 80% from 25% of that by oxide materials. Further more, a crystal of 4.3×4.1×2.2mm was obtained by adding ZrO2.