Structural, Microstructural, and Dielectric Properties of Nickel-Doped PbTiO3 Ceramics Synthesized by the Hydrothermal Process

In this work, an experimental study was conducted on the structural and dielectric properties for nickel-doped Pb1-xNixTiO3 (PNT) perovskite-based ceramics with varying nickel concentrations (x (wt) = 0%, 5%, 10%, 15%, 17%, and 20%). The ceramics were prepared using the hydrothermal process at low temperature, which was compared to the solid-state method. The precursors, in stoichiometric amounts, were placed in an alkaline environment using an autoclave and were heat-treated at 180 degrees C for 24 h. The obtained powders underwent characterization after filtration, washing, and drying. X-ray diffraction analysis with Rietveld refinement highlighted that the powders crystallize in a tetragonal perovskite structure with P4mm space group and transform into a pseudo-cubic structure upon the introduction of nickel cations into the lattice. Scanning electron microscopy was used to observe the material structures at the micro level, revealing a homogeneous grain shape with a decrease in average grain size as the nickel concentration in the compound increased. Raman spectroscopy was employed to study the active phonon modes of the materials. The dielectric properties of the different Pb1-xNixTiO3 compositions were analyzed using dielectric spectroscopy in a temperature range from room temperature to 500 degrees C, and at frequencies ranging from 1 kHz to 1.6 MHz. The results confirm the insertion of nickel cations into the PbTiO3 lattice and highlight the resulting enhanced dielectric constant (epsilon(r)), transition temperature (T-C), and dielectric loss (tan delta).