Optical and electrical properties of barium titanate-hydroxyapatite composite screen-printed thick films

In this paper we will study the effect of the presence of hydroxyapatite (HA-Ca-10(PO4)(6)(OH)(2)) on the dielectric permittivity and losses of the barium titanate (BTO-BaTiO3) thick films. These films were prepared in two layers geometry using the screen printing technique on Al2O3 substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite (HA) used in the films. We also look for the effect of the grain size of the BTO and HA on the final properties of the film. The samples were studied using X-ray diffraction, scanning electron microscopy (SEM), Raman and infrared spectroscopies, dielectric permittivity and losses measurements. The study of the dielectric permittivity and losses was done in the radio-frequency range (100 Hz-10 MHz). The role played by the firing process in the film preparation and the crystallite size of HA and BTO on the dielectric constant and structural properties of the films are discussed. (C) 2004 Elsevier SAS. All rights reserved.