Influence of Cr doping on structure and dielectric properties of LixCryNi1−x−yO ceramics

LixCryNi1−x−yO (where x=0.30; y=0.02, 0.05, 0.10) ceramics were prepared using a sol–gel process and sintered at 1300 °C for 5 h. The sintered pellet samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. Dielectric properties were also investigated. All sintered samples exhibited only cubic rock-salt NiO structure and giant dielectric constants of ~104–105 over the measured frequency range with low loss tangents. Both values of dielectric constants and loss tangents decreased with increasing Cr content. This was related to the reduction of grain size as Cr content in LiCrNiO increased. Giant dielectric constants in these samples possibly resulted from boundary layer capacitor structures and partially from defect dipoles. The sample with Cr a molar ratio of 0.10 had the best dielectric properties with very high εr (4.76×104) and the lowest tanδ (0.46) measured at 10 kHz and room temperature.