Dielectric and ultrasonic attenuation at low temperatures on BST ceramics with high strontium concentration

ABSTRACT

This work presents experimental investigation of the low-temperature dielectric and ultrasonic responses of (Ba_1−xSr_x)TiO₃ ceramics with high strontium concentration compositions, x > 0.825. Impedance spectroscopy measurements were performed at frequencies between 0.1 kHz and 100 kHz, and the results were correlated to those obtained with ultrasonic measurements. The anomalies observed in ultrasonic data were associated to ferroelastic and ferroelectric phase transitions. For x = 0.875 the “pinching” of ferroelectric phase transitions was observed. A brief discussion associates some peaks in the ultrasonic attenuation to anomalies in the dielectric response at temperatures below phase transition.

KEYWORDS:

• BST ceramics
• low temperatures
• ultrasonic attenuation
• dielectric
• phase transitions

Funding

The authors wish to thank CNPq and FAPESP (Brazilian agencies) and PEDECIBA (Uruguayan agency) for financial support. Ruyan Guo and Amar S. Bhalla acknowledge the support of NSF grants DMR 0844081 and ECCS 1002380.