Bismuth-substituted hydroxyapatite ceramics synthesis: Morphological, structural, vibrational and dielectric properties

New hydroxyapatite (HAp) ceramics substituted with 10, 30 and 50 at.% of bismuth were synthesized by conventional solid state reaction at high temperature T = 1300 degrees C, and characterized via X-ray diffraction, scanning electron microscopy, Fourier transform infrared and Raman spectroscopies; dielectric properties were also investigated. The hydroxyl groups observed in infrared spectra confirmed the HAp phase in the studied samples. The crystallite size was estimated by Scherrer's formula and the Williamson Hall plot, while lattice parameters and the unit cell volume of the samples were measured according to Bi content.Scanning electron microscope images revealed the presence of grains with irregular sizes developed within larger aggregations. Measured relative dielectric permittivity and dielectric loss are slightly affected by Bi content, while the alternating current conductivity increases with a rise frequency, and decreases at increasing of Bi content. The HAp-Bi50% sample presents the optimal dielectric properties.