Papers by Author: Hao Su Luo

Abstract: (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 (abbreviated as NBBT100(1-x)/100x or NBBT100x) solid solution single crystals with x=0, 0.06, 0.08, 0.10, 0.20, 1.0 were grown using top-seeded solution growth (TSSG) method. Dielectric, piezoelectric and ferroelectric properties of NBBT crystals were investigated as a function of temperature, frequency, composition and crystal orientation. The temperature (Tm) corresponding to dielectric maximum and the depolarization temperature (Td) decrease with increasing x. The <001> oriented NBBT90/10 single crystal shows excellent piezoelectric performance with piezoelectric constant (d33) value about 275pC/N and exhibits relatively smaller coercive field (Ec) of 2.49 kV/mm and dielectric loss tanδ of 2.9 %, indicating a more adaptive engineered domain structure.

Abstract: High purity BaTiO3 single crystal was aged below its Curie temperature for different times. The reverse transformation (from tetragonal to cubic) temperature was measured precisely by differential scanning calorimetry (DSC). It was observed that the reverse transformation temperature increased with increasing aging time, indicating ferroelectric phase became stable with aging. This behavior is the same as found in ferroelastic alloys. The origin of the stabilization effect in ferroelectric single crystals was discussed with respect to the distribution of point defects.