Investigation of the Effects of Reduced Sintering Temperature on Dielectric, Ferroelectric and Energy Storage Properties of Microwave-Sintered PLZT 8/60/40 Ceramics

Ajeet Kumar,A R James,Jungho Ryu,Sivanagi Reddy Emani,K C James Raju

doi:10.3390/en13236457

Abstract

In this study, (Pb0.92La0.08) (Zr0.60Ti0.40) O3 (PLZT 8/60/40) ceramics were synthesized using a high-energy ball-milling technique followed by microwave sintering at different temperatures from 900 °C to 1200 °C. The optimal microwave sintering temperature for the PLZT 8/60/40 ceramics was found to be 1150 °C, which is relatively low compared with conventional sintering temperature. The sintered ceramics show the pure perovskite phase, uniform grain microstructure (1.2 µm) and high density (~99.5%). The polarization vs. electric field (P-E) hysteresis curves were used to investigate the ferroelectric and energy storage properties. The switching characteristic in P-E loops and occurrence of domain switching current in current vs. electric field (I-E) loops confirms their ferroelectric nature. The PLZT ceramics, which were sintered at 1150 °C, show the highest remnant polarization (Pr) of ~32.18 μC/cm2 and domain switching current (Imax) of ~0.91 mA with a low coercive field (Ec) of ~10.17 kV/cm. The bipolar and unipolar strain vs. electric field (S-E) hysteresis loops were also measured and the highest unipolar strain was found to be ~0.26% for the PLZT ceramics sintered at 1150 °C. The unipolar S-E curves were used to derive the piezoelectric coefficient (d33~495 pm/V) and a strain hysteresis loss (~5.8%).

Highlights

Lead lanthanum zirconium titanate (PLZT) is one of the most studied electroceramics due to its technological importance in various applications [1,2,3]
The PLZT ceramics, microwave sintered at 900 ◦ C and 1000 ◦ C show the grain size in the submicron range
When the ceramic microwave sintering temperature was increased from 1050 ◦ C to 1200 ◦ C, the grain size of the ceramics was increased from the submicron to the micron region

Summary

Introduction

Lead lanthanum zirconium titanate (PLZT) is one of the most studied electroceramics due to its technological importance in various applications [1,2,3]. In PLZT ceramics, the ratio of La/Zr/Ti decides the morphotropic phase boundary (MPB) and influence the microstructure and electrical characteristics. The nature of the material such as ferroelectric (FE), paraelectric (PE), anti-ferroelectric (AFE) and relaxors ferroelectric (RFE) is decided by the La/Zr/Ti ratio [4,5,6]. PLZT ceramics of different natures (FE, PE, AFE and RFE) or different compositions (ratio of La/Zr/Ti) possess a higher piezoelectric coefficient, electromechanical coupling coefficients with a wide range of dielectric constants. These properties are sufficiently large to exploit in different types of piezoelectric device such as sensors, actuators and energy harvesting devices.

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