Temperature Dependence of Dielectric Properties of Barium Titanate Ceramic Films Prepared by Aerosol Deposition Method

Abstract

BaTiO3 (BTO) thick films were deposited by an aerosol deposition (AD) method and their physical and electrical properties were investigated. The films were deposited on Pt/Ti/Al2O3 and Pt/Ti/ZrO2 (YSZ) ceramic substrates at a thickness of approximately 2 µm. Two powders were selected for this investigation. The primary BTO powders have a perovskite structure with average particle diameters of 0.1 and 0.5 µm, respectively, and are commercially available as raw powders (BT01 and BT05). These powders were heat-treated for 1 h at 1000 °C in a furnace prior to deposition. The particle size was not changed by the heat treatment while a large aggregate with a size of 10–50 µm was observed in the heat-treated BT01 powder. As-deposition films showed a relative dielectric constant (εr) of approximately 100 regardless of the powder and the substrates used. A post-deposition heat treatment at 1000 °C for 1 h was carried out for the BTO thick films. After annealing, the εr was improved. The BTO thick films prepared from BT01 heat-treated powders on the Pt/Ti/YSZ ceramic substrates showed an εr at room temperature of 1120 which is higher than that of 910 of the films deposited on Pt/Ti/Al2O3. The BTO films fabricated from BT05 heat-treated powders on Pt/Ti/Al2O3 ceramic substrates have an εr of 650, larger than that for the films deposited on Pt/Ti/YSZ. Control of powder aggregation by heat treatment along with the use of AD as the method of film fabrication and appropriate substrate selection are demonstrated to be important parameters to obtain BTO ceramic films with a high εr.