Effect of sintering conditions on colossal dielectric properties of (Tb1/2Nb1/2)0.01Ti0.99O2 ceramics

In this study, we investigated various sintering temperatures (1200 degrees C-1450 degrees C) and durations (2-6 h) conditions for preparing (Tb1/2Nb1/2)(0.01)Ti0.99O2 (TNTO) ceramics. By employing high sintering temperatures (>= 1350 degrees C) and extended sintering durations (>= 4 h), we successfully achieved ultra-high dielectric permittivity values (epsilon' similar to 2.2 - 4.1 x 10(4)) and remarkably low loss tangent values (similar to 0.025-0.079). Remarkably, the temperature coefficient of the TNTO ceramic, sintered at 1350 degrees C, exhibited exceptional stability, maintaining a value of approximately 15% even at 200 degrees C. Additionally, we examined the phase structure and microstructure of the TNTO ceramics to gain insights into their colossal permittivity (CP) behavior. The analysis revealed the presence of rutile TiO2 and TbNbTiO6 phases, and the ceramics exhibited a high-density microstructure under high-temperature sintering conditions. The impedance spectroscopy analysis revealed that the primary contributor to the observed CP behavior was the interfacial polarization mechanism. The observed increase in the epsilon' value, correlated with the enlargement of the average grain size, can be attributed to the effect of the internal barrier layer capacitor. However, when the sintering time >= 4 h, the grain size did not significantly affect the epsilon' value, possibly due to reaching the maximum capacity of electron production for the interfacial polarization process (i.e., the maximum intensity of polarizability). This study provides valuable insights into optimizing the sintering conditions for TNTO ceramics and related compounds, laying the groundwork for the development of a new CP oxide suitable for practical applications.

Automated summary

By adjusting the sintering conditions, including temperature and duration, TNTO ceramics with ultra-high dielectric permittivity and low loss tangent were successfully prepared. The analysis of phase structure and microstructure provided insights into the mechanism for the colossal permittivity behavior.