Hydrothermal synthesis and characterization of rare-earth doped BaTiO3 nanoparticles

Abstract

In order to improve the dielectric properties of MLCCs, many studies have been conducted over the past several decades on the doping effect on dielectric properties and defect chemistry of barium titanate (BaTiO$_3$) bulk ceramic. In particular, dielectric properties of trivalent rare-earth doped BaTiO$_3$ bulk have been mainly characterized which is synthesized and doped through solid-state reaction or sintered with rare-earth oxide. However, as the fine particle is required for the thin dielectric layer less than 150 nm due to miniaturization of electronic devices, fine powder coated or doped with a rare-earth material is needed. Accordingly, doped barium titanate bulk ceramic synthesized by hydrothermal method, which facilitates synthesis of fine particles less than 100 nm have been characterized. However, research on powder characterization is insufficient. In this work, we synthesized BaTiO$_3$ nanoparticles with La$^{3+}$ and Nd$^{3+}$ precursors, which are expected to be doped into Ba-site, and were characterized through X-ray diffraction and spectroscopic analysis. Unlike La$^{3+}$, Nd$^{3+}$ was not incorporated into BaTiO$_3$ lattice, and the much smaller ionic radius of Nd$^{3+}$ than Ba$^{2+}$ may result in difference in incorporation behaviors. Analysis of heat-treated BaTiO$_3$ powder showed that there are La$^{3+}$ based amorphous impurities which can be additionally incorporated during the sintering process.