Volume 129, Number 3, February 2020
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||02 March 2020|
The origin of weak coupling between polar clusters in Ta2O5-doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3
1 Guangxi Key Lab of Optical and Electronic Functional Materials and Devices, College of Materials Science and Engineering, Guilin University of Technology - Guilin 541004, China
2 College of Energy and Building Environment, Guilin University of Aerospace Technology - Guilin 541000, Guangxi, China
3 College of Mechanical and Electronic Engineering, Jiangxi College of Applied Technology - Ganzhou, 341004, Jiangxi, China
Received: 10 November 2019
Accepted: 12 February 2020
Ta2O5-doped 0.94Bi0.5Na0.5 TiO3-0.06BaTiO3 [()(0.94BNT-0.06BT)-xTa ()] ceramics were prepared by a solid-state reaction technique. The single perovskite structure with space group R3c of the ceramics was identified by X-ray diffraction (XRD). Raman spectroscopy revealed the evolution of the local structure with Ta2O5 concentration. The temperature dependence of dielectric permittivity of the ceramics were deconvoluted by three Gaussian distribution functions which suggests that three dielectric anomalies exist in this system. The low-temperature dielectric anomaly exhibits a typical relaxor behavior with strong frequency dispersion (reentrant relaxor behavior). The activation energy derived from the V-F law is 0.298 eV, 0.338 eV, 0.412 eV and 0.449 eV, for , 0.005, 0.01 and 0.02, respectively. The mid-temperature and high-temperature anomalies are attributed to two structure phase transitions. The increase of the activation energies suggests that the coupling between polar clusters or polar nanoregions (PNRs) becomes weaker. The origin of the interaction between PNRs and phase transition behavior has been proposed according to the average structure, local structure and defect compensation mechanism of the system.
PACS: 77.84.-s – Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials / 77.80.Jk – Relaxor ferroelectrics
© EPLA, 2020
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