STRUCTURE, SITE OCCUPATIONS AND DIELECTRIC PROPERTIES OF LA AND TM CO-DOPED BATIO₃ CERAMICS

Yue Liang, Dayong Lu

ABSTRACT:The nominal (Ba1–xLax) (Ti1–xTmx) O3 (x = 0.01‒0.15) (BLTTm) ceramics were prepared at 1400 °C using a mixed-oxides method. The structure, solubility limit, site occupations, and dielectric properties were investigated using X-ray diffraction (XRD), Raman spectroscopy (RS), electron paramagnetic resonance (EPR), and dielectric measurements. The solubility limit of La/Tm in the BaTiO3 lattice was determined by XRD to be x = 0.08. BLTTm has a tetragonal perovskite structure for x ≤ 0.03 and a pseudo-cubic structure for 0.05 ≤ x ≤ 0.08. The dielectric thermal behavior of BLTTm with x = 0.05 satisfied X6T specification, with ε′RT = 1756 and a very low tan δ (< 0.02) below 100 °C. Tm3+ ions in BLTTm exhibited an asymmetric amphoteric behavior. Both reduction in Mn impurities of Mn4+/Mn3+ to Mn2+ and creation of high-intensity Ti vacancies are responsible for the very low tan δ in BLTTm with x = 0.05.

Keywords:La and Tm co-doped BaTiO3 ceramics, site occupations, X-ray diffraction, dielectric properties, electron paramagnetic resonance.