Developmental Prospects of the Methods for Synthesizing Titanates of the Perovskite-Type Structure and Their Doping with Rare-Earth Elements

Abstract

A review of methods for fabricating titanates of a perovskite-type structure and their doping with rare-earth elements is presented. The results of the scientific research of authors from different countries related to the study of the effect of doping titanates of the perovskite structure by rare-earth elements on their electromagnetic properties are discussed. The content of the work also includes information on the use of titanates of the perovskite-type structure in various industries. A comparative analysis of some morphological properties (particle size and structure) and electromagnetic characteristics (dielectric constant, Curie temperature, and modulus of longitudinal oscillations (d33)) of powders fabricated (and doped) by different methods is carried out by the example of barium titanate (BaTiO₃). Procedures for fabricating BaTiO₃ by various methods, such as solvothermal, hydrothermal, sol–gel, chemical deposition, and solid-phase sintering, are described. The results of studying the influence of the variation in process parameters (temperature, pH, composition of the initial mixture of materials, and concentration of reagents) on the phase, morphology, and formation rate of BaTiO₃ particles during the hydrothermal synthesis (with the use of BaCl₂, TiCl₄, and NaOH as initial materials) are presented. The experiments on studying the influence of the microwave-radiation power during the solid-phase sintering of BaCO₃ and TiO₂ on dielectric and ferroelectric properties of BaTiO₃ are also presented. An analysis of fabrication methods of BaTiO₃ and its doping by rare-earth elements results in the statement that the hydrothermal method and solid-phase sintering, including the application of the microwave radiation, are currently the most promising fabrication technologies of materials with the perovskite-type structure with specified properties.