Study of the solubility of La3+–Dy3+ defect complexes and dielectric properties of (Ba1−xLax)(Ti1−xDyx)O3 ceramics

Based on the double-site compensation mode, the solubility of LaBa
• –DyTi′ defect complexes and the dielectric properties of (Ba1−xLax)(Ti1−xDyx)O3 (0.03≤x  ≤0.20) ceramics (BLTD) were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, electron paramagnetic resonance (EPR), and dielectric measurements. The solid solubility of LaBa
• –DyTi′ defect complexes in the BaTiO3 lattice was determined to be x=0.17. With an increase in x, the increase in the unit cell volume was linear and satisfied Vegard׳s law. The dielectric-peak temperature (Tm) decreased rapidly at a rate of −23 °C/at% LaBa
• –DyTi′. The BLTD ceramics with x  =0.05 and 0.07 met the Y5V specification with a higher room-temperature permittivity (εRT′~4000 and ~3000) and a lower dielectric loss (tanδ<0.04). A weak g=2.004 EPR signal associated with ionized Ti-vacancy defects appeared in all of the BLTD ceramics. The exclusive occupations of La3+ ions at Ba sites and the preference for the self-compensation mode by Dy3+ ions are responsible for the formation of predominant LaBa
• –DyTi′ defect complexes and the appearance of the minute concentration of Ti vacancies and DyBa
• –DyTi′ defect complexes.