The article considers one of the problems hindering the use of ceramic piezoelectric materials based on the BiFeO3 - BaTiO3 phases, which is caused by high values of the dielectric loss tangent of these materials. It is assumed that this is due to different electrical conductivity of individual grains of this type of piezoelectric ceramics (Maxwell-Wagner effects), caused by the presence of iron ions in their composition, which have different oxidation states. In order to equalize the oxidation states of iron ions found in the grains of the considered ceramics, we used annealing of its samples in an atmosphere formed as a result of thermal decomposition of ammonium carbonate. It was found that this technique allows: a) to reduce the values of tgδ of the CPM by 6 - 7 times; b) increase the polarizing field strength by at least 40%, and the value of the longitudinal piezoelectric modulus to 140 pC/N.
Keywords: piezoelectric material, electrical conductivity, dielectric loss, defect, iron ions, Maxwell-Wagner effect, reducing atmosphere, ammonium carbonate