Barium titanate ͑BaTiO 3 , BT͒-bismuth magnesium titanium oxide ͓Bi͑Mg 0.5 Ti 0.5 ͒O 3 , BMT͔ system ceramics were prepared in an ambient atmosphere in order to increase the Curie temperature ͑T c ͒ of BT above 132°C. A single perovskite phase was observed for BT-BMT ceramics with BMT compositions less than 50 mol %, and their relative densities were greater than 94%. Synchrotron measured x-ray diffraction patterns revealed that all the cations in the ceramics were homogeneously distributed. The temperature dependence of the dielectric properties revealed that the BT-BMT system ceramics exhibited relaxorlike characteristics with a dielectric maximum temperature as high as 360°C for the 0.5BT-0.5BMT ceramic. The apparent piezoelectric constant ͑d ‫ء‬ ͒ was 60 pC/N for the 0.4BT-0.6BMT ceramic. Based upon these results, the BT-BMT system shows potential as a new type of lead-free material for high T c piezoelectric applications.

Epitaxial (1−x)BaTiO3−xBi(Mg0.5Ti0.5)O3 films with x = 0 − 0.9 were grown on (111)cSrRuO3//(111)SrTiO3 substrates by pulsed laser deposition (PLD). Plotting the temperature where dielectric constant reaches a maximum {T[ɛr(max.)]} versus Bi(Mg0.5,Ti0.5)O3 content present minimum at x = 0.1. On the other hand, the remanent polarization (Pr) and the effective transverse piezoelectric constant [d33(eff.)] showed minimum at 0.1 and 0.2, respectively, but increased with the increase of x in (1−x)BaTiO3−xBi(Mg0.5Ti0.5)O3 above these values. These results show the simultaneous increase of T[ɛr(max.)] and d33(eff.) for the films above x = 0.2 that normally showed treads off characteristics.

Barium titanate (BaTiO 3 , BT)bismuth magnesium titanium oxide (Bi(Mg 0.5 Ti 0.5 )O 3 , BMT) solid solution system ceramics were prepared using nanoparticles in atmosphere to enhance Curie temperature (Tc) of BT, 132°C, to much higher temperature. Optimization of calcination and sintering conditions resulted in a formation of a perovskite single-phase, and their densities were always greater than 94%. The synchrotron XRD measurement revealed that the all ions in the ceramics had almost homogeneous distribution. Temperature dependence of dielectric property revealed that the BTBMT system ceramics was typical relaxor materials, and for the 0.5BT0.5BMT ceramics, the dielectric maximum was clearly observed at 360°C. Finally, their apparent piezoelectric constant (d*) were measured by electric-field dependence of strain at room temperature, and the d* value was measured at around 60 pm/V for the 0.4BT0.6BMT ceramics.

Relaxor characteristics of (1-x)BaTiO3-xBi(Mg1/2Ti1/2)O3 (x=0.1–0.7) ceramics were investigated. Microstructural observation showed second phases and no domain structure for the sample with x=0.6. Deviation from the Curie-Weiss behavior was found in temperature dependence of the inverse permittivity for all the samples. The stronger dielectric dispersion was found for x=0.6 and 0.7 and they were described by the Vogel-Fulcher relationship. The temperature dependence of the remanent polarization and coercive field indicated the freezing temperature was 100~150°C for x=0.6. The strong dielectric dispersion of x=0.6 is believed to be induced by the structural disorder due to the second phases.