The dielectric, piezoelectric and elastic properties of 0.91(PbZn1/3Nb2/3)O3–0.09PbTiO3 single crystals have been investigated as functions of temperature and applied electric field. Two multiple phase transitions at 68°C and 178°C, the crystal changing from the rhombohedral ferroelectric phase to tetragonal ferroelectric and then to cubic paraelectric, have been observed. Both the transitions are of first-order, but both are slightly diffused. Significant increases in the dielectric, piezoelectric and elastic constants are observed at the lower transition point. In particular, the sample poled along the pseudo-cubic [001] axis reveals anomalously large piezoelectric and electro-mechanical coupling constants at room temperature in the rhombohedral phase (d [001]//=1500×10-12 C/N, k [001]//=0.92).

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Solid solution ceramics in the Ba(Zn1/3Nb2/3)O3(BZN)–Sr(Zn1/3Nb2/3)O3 (SZN) system have been studied with a view to finding materials for use as dielectric resonators at microwave frequency. The relative dielectric constant and the unloaded Q at 10 GHz are respectively 41 and 5400 for BZN, and 40 and 2000 for SZN. The temperature coefficient of the resonant frequency is estimated as 30 ppm/°C for BZN and -38 ppm/°C for SZN. The dielectric constant of 0.3 BZN–0.7 SZN ceramic is nearly independent of temperature, which gives a very small estimated temperature coefficient of the resonant frequency of -5 ppm/°C.

The electrostrictive coefficients Q33 and Q13 of Pb(Mg1/3Nb2/3)O3 ceramics have been precisely determined over a wide temperature range from -110°C to 100°C, using three different methods: strain gauge, piezoelectric resonance and interferometric techniques. A quadratic relation between induced strain and electric polarization holds even in the ferroelectric phase, as well as in the paraelectric phase. The electrostrictive coefficients are nearly temperature-independent with values of Q33=2.3(±0.2)×10-2 m4C-2 and Q13=-0.64(±0.05)×10-2 m4C-2. The field-induced piezoelectric coefficients d33 and d31 were also measured at room temperature as a function of dc bias field. The values of d33/ε3 and d31/ε3 are proportional to the induced electric polarization. The electrostrictive coefficients calculated from the slopes are in good agreement with those obtained by the strain-gauge method.