MgO単結晶製るつぼによるPbTiO₃単結晶の育成及び評価

抄録

The growth of PbTiO₃ single crystals was studied using a MgO single crystal crucible by flux cooling method. As-grown PbTiO₃ single crystals were used for measurements of relative dielectric constant, dielectric loss, dc-resistivity and pyroelectric coefficient. The results obtained are as follows. In this study the preparation conditions to obtain large PbTiO₃ single crystals are summarized as follows. When the raw material mixed with the starting material/flux=PbTiO₃/PbO (weight ratio)=0.339 was used, melted and cooled, a transparent PbTiO₃ single crystal with a maximum size of 2.7×2.7×1.2mm was obtained at a cooling rate of 5°C/h in the range of 600° and 400°C near the Curie point, and 20°C/h in the ranges of 1100° to 600°C and 400°C to room temperature. Mg²⁺-doped PbTiO₃ single crystals prepared in a MgO single crystal crucible were better than that in a platinum crucible. They were obtained in the middle part of the crucible at the upper part of flux as large plate-like crystals, containing 3000 to 5000ppm MgO from EPMA spot analysis of the crystal surface. From measurements of pyroelectric constant, the pyroelectric properties of Mg²⁺-doped PbTiO₃ single crystals were elucidated. The present single crystals were found to be particularly superior with respect to dc-resistivity and dielectric loss to those of pure PbTiO₃ single crystals.