Electrical Characteristics of Ho doped BaTiO3 Ceramics

Abstract

In this paper, electrical characteristics of Ho2O3 doped BaTiO3 ceramics were shown, using new method for measuring samples. The BaTiO3 doped samples were sintered at 1320°C for 4 hours. The concentration of the additives were from 0.05 to 1.0 at% Ho. The density was ranged from 83% to 91% of theoretical density (TD). The samples of BaTiO3 ceramics doped with Ho2O3 are characterized by spherical and irregular polygonal grains. The average grain size for samples doped with low content of Ho2O3 (0.05 at% Ho) ranged from 10 μm to 30 μm. An increase in dopant concentration causes a decrease in the average grain size in the investigated samples. So it is for samples doped with 1.0 at% Ho, grain size range between less than 1 mm – 2 mm. The variation of dielectric permittivity with temperature were measured in the temperature range from 30°C to 180°C and the frequency range from 100 Hz to 1 MHz. For measurement electrical characteristic a new method was used, which implemented to automate the sampling and to enable measurement without a human factor. The software application is connected via USB communication to a microcontroller, which measures the temperature in the furnace. When the temperature reaches the defined value, the microcontroller sends information to the software application. Then the application through GPIB communication activates the LCR meter, which measures the defined parameters of the tested samples. Based on parameters such as dielectric constant (εr), tangent losses (tan δ) and impedance, the characteristics of the tested samples were determined. Using the Curie-Weiss law and modified Curie-Weiss law, based on the measured values of the parameters, the Curie constant and the exponent of nonlinearity were determined.