Dielectric properties of barium titanium ceramics doped by lanthanum oxide

Abstract

The method of oxalate co-precipitation assisted with microwave is used for the synthesis of pure barium titanate (BT) particle with a diameter of 30–50 nm by choosing tetrabutyl titanate Ti(OC₄H₉)₄ (98.0%), barium nitrate Ba(NO₃)₂ (99.5%), oxalate H₂C₂O₄ (99.5% purity) and nitric acid HNO₃ (65 ∼ 68%) as starting materials. Lanthanum oxide is doped in barium titanate powders to prepare ceramics by pelleting, forming, dumping, sintering and other steps. The structure and morphology of ceramics are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The dielectric constant and dielectric loss are obtained by dielectric frequency analyzer. The results show that grain size and tetragonality of the barium titanate ceramics doped by lanthanum oxide sintered at 1270 °C for 3 h are found to decrease with the increase of dopants concentration. Dielectric constant increases at first and then decreases as La₂O₃ concentrations grow, reaching the maximum value when the concentration is 0.3 mol%. The ceramic samples transform from normal ferroelectric to the ferroelectric with diffused phase transition.

Keywords:

• Barium titanate ceramic
• lanthanum oxide
• dielectric properties
• grain size

Acknowledgment

The authors thank the financial support from the National Natural Science Foundation of China (No. 51072162).