PbTiO_3単結晶の育成と電気的性質に及ぼすLi_2O及びNa_2Oの添加効果

概要

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PbTiO_3 single crystals containing Li_2O or Na_2O were grown by a flux method. Electrical measurements were carried out for as-grown crystals doped with 0.01 wt% Li_2O or 0.10 wt% Na_2O. (1) The addition of Li_2O and Na_2O increased the size of obtained crystals, and gave also the crystals with low defect concentration. (2) The grown PbTiO_3 crystals by the addition of Li_2O (0.7 wt%) and Na_2O (0.7 wt%) were highly transparent red-brown and brown single crystals, respectively, and had average size of 3.0×2.8 x 1.1 mm and 3.6×2.8×1.0 mm. (3) The content of Li_2O in all the Li-doped crystals was less than 0.01 wt%, whereas the Na_2O content was more than 0.07 wt% and increased with increasing addition of Na_2O. (4) Crystals doped with Li_2O showed no variations in the lattice constant, but the lattice constant of c-axis and axial ratio of crystals doped with Na_2O were smaller than those of undoped crystal. (5) Electrical properties of the crystals were affected by the addition of Li_2O or Na_2O. The electrical conductivity of crystals was very low (10^<-10>S・cm^<-1>) for Li_2O addition but that of crystals for Na_2O addition was high (10^<-8>S・cm^<-1>) at room temperature. At temperature above 300℃, the current-voltage characteristic curve of the crystal doped with Li_2O was composed of two parts, ohmic and non-ohmic ones. E_H decreased remarkably with increasing temperature.
1992-10-01