Radhapiyari Laishram

Improved electrical properties of PbZrTiO3/BiFeO3 multilayers with ZnO buffer layer

In this study, the effect of ZnO buffer layer on the electrical properties of PbZrTiO3/BiFeO3 (PZT/BFO) multilayers has been reported. For this, PZT/BFO multilayers were spin-coated with and without ZnO buffer layer on platinized silicon wafers. X-ray diffraction results of both the films showed polycrystalline phase pure perovskite structure. Both the films show a dense and homogeneous grain structure. The electric properties of the films were measured. The ZnO buffered multilayer thin film showed ∼3 times improvement in remnant polarization compared to the multilayer thin film with no buffer. The buffered samples were found to have higher dielectric constant (1000 at 100 Hz) compared to that of sample (580 at 100 Hz)) with no buffer. Dielectric constants of both the films were found to be ∼30% tunable at 5 V. The buffered film also showed low leakage current density and higher dielectric breakdown compared to the multilayer thin film without buffer.

Study of dielectric and piezoelectric properties of neodymium doped Ba(0.85-x)NdxCa0.15Zr0.1Ti0.9O3 ceramics

ABSTRACT Ba(0.85-x)NdxCa0.15Zr0.1Ti0.9O3 (x = 0, 0.005, 0.010, 0.015, 0.020, 0.025) ceramic compositions were synthesized by solid state reaction method. Effects of Nd3+ on the microstructure, dielectric, and piezoelectric properties of the ceramics were studied. X-ray diffraction study reveals that Nd3+ ions diffuse into Ba(0.85-x)NdxCa0.15Zr0.1Ti0.9O3 lattice to form a solid solution of single perovskite structure having tetragonal symmetry. It was found that cell volume, crystallite size, tetragonality, d33 and Pr change with increasing Nd3+ content. d33 was optimized at 270pC/N for x = 0.015. The study reveals that optimum doping of Nd3+ in Ba(0.85-x)NdxCa0.15Zr0.1Ti0.9O3 can enhance its dielectric and piezoelectric properties.

Effect of Ball Milling Time on the Electrical and Piezoelectric Properties of Barium Titanate Ceramics

Barium Titanate (BaTiO3) is the first piezoelectric ceramic developed and most widely used though for few decades it has been replaced by better performed lead based materials like PZT, PLZT, etc. for piezoelectric applications. Recently, however, due to the environmental concern caused by lead based materials, researchers have been giving importance to this material and trying to improve its piezoelectric and electromechanical properties by performing various treatments. The present work is also an effort in this direction. Barium titanate (BaTiO3) powder was synthesized by solid state reaction of BaCO3 and TiO2 at 1050°C. X-ray diffraction analysis of the powder showed the single phase perovskite structure of BaTiO3. The powder was milled to produce nanocrystalline powders using a planetary ball mill. Different samples were prepared by varying the milling time from 1 to 30 hours, keeping the milling speed fixed at 250 rpm. All the milled powders were examined with TEM. With increasing milling time, the particle size first decreases and attains a minimum of 28.59 nm at 20 hours of milling time. However, further increase in milling time results in increase of the particle size. The electrical and piezoelectric properties of the ceramic samples formed by these nanocrystalline powders were studied.

Low Temperature Deposited BST Thin Films for RF MEMS Switch

BST thin films of optimized target composition of Ba0.6Sr0.4TiO3 have been deposited on Cr-Au coated Si substrate by Pulsed Laser Deposition technique with low substrate temperature of 100°C using different laser energies (250 mJ, 300 mJ and 350 mJ). The structural, morphological and electrical studies have been carried out for all the films. The value of dielectric constant and dielectric loss for the film deposited with different laser energies were in the range of 18–20 and 0.04–0.07 respectively. The thickness of the film was 0.4 μm. All the films show higher resistivity (∼107Ω-cm) and high dielectric breakdown strength (∼500 kV/cm). The observed results suggest that the low temperature deposited BST thin films are suitable for RF MEMS Switch application.