Dielectric properties of BNT-xBT prepared by hydrothermal process

The BNT ceramic sample might be a good replacement for PZT piezoelectric in industrial applications, especially in energy harvesting from crystal vibrations. In order to enhance the performance of BNT ceramic, the solid solution was chosen by substitution with Ba+2 at Morphtropic Phase Boundary (MPB). The BNT-xBT powders with x=1, 0.07, 0.06 and 0 were prepared by the hydrothermal method with average particle size (65–150nm) at (90∘C/72h). The ceramic disc was sintered at (1150∘C/4h) and showed excellent relative density of about 96%. The results of X-ray diffraction (XRD) confirmed the MPB for x=0.06 and 0.07, while the BNT had a rhombohedral structure and BT had a tetragonal structure. The dielectric measurements showed that BNT, BNT-7BT, BNT-6BT behave as the relaxator ferroelectric and showed a strong dependence on frequency, especially in the MPB region while BT behaves as a normal ferroelectric. Both the Curie temperature and depolarization temperature decrease at the MPB region and showed strong dependency on frequency

The nanostructure of barium dititanate prepared by hydrothermal method

The dielectric ceramic of barium dititanate compound BaTi2O5 had been prepared through the hydrothermal process by applying different parameters, such as pH-value, reaction time, temperature and pressure. The prepared powders were examined by X-ray diffraction (XRD). The predominant phase was a monoclinic phase with lattice constants (a=16.6381, b=3.555, c=9.3406 Å), (β=107.47∘, α=γ=90∘), and the unit cell volume (527 Å3). The surface morphology was demonstrated by Scanning Electron Microscopy (SEM). It exhibited the grains in spherical and elliptical shapes with high homogeneity. The shapes of nanostructure were analyzed by Transmission Electron Microscopy (TEM). The appearance of nanostructures like the nanoparticles and nano rods were found. The size of nanoparticles was in the range of 9–31nm, and size of nanorods was 32–37nm. The dielectric measurements were done by using LCR meter at different temperature and frequencies (10, 50 and 100kHz). It was clear that the Curie temperature had a high value up to (485∘C). The relative permittivity was partially changed for two prepared samples regarding high pressure and long reaction time, which were the main preparation conditions of hydrothermal method