Barium titanate (BaTiO3, BT) bismuth magnesium titanium oxide (Bi(Mg0.5Ti0.5)O-3, BMT) solid solution system ceramics were prepared using nanoparticles in atmosphere to enhance Curie temperature (Tc) of BT, 132 degrees 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%.0 The synchrotron XRD measurement revealed that the all ions in the ceramics had almost homogeneous distribution. Temperature dependence of dielectric property revealed that the BT-BMT system ceramics was typical relaxor materials, and for the 0.5BT-0.5BMT ceramics, the dielectric maximum was clearly observed at 360 degrees 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 0.4BT-0.6BMT ceramics.