J. Paul Praveen

Enhanced piezoelectricity in lead-free BCZT piezoceramics for sensor applications

Piezoelectric properties of the recently developed lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCZT) ceramics has been improved by suitable additives. In the present study, different tetravalent additives (SiO2, GeO2, MnO2 and CeO2) have been added to BCZT ceramics and their effect on phase structure and piezoelectric properties of BCZT ceramics have successfully been investigated. X-ray diffraction spectra of BCZT-0.08 wt.% XO2 (X = Si4+, Ge4+, Mn4+, and Ce4+) ceramics showed the diffusion of additives into the BCZT lattice and form a single-phase perovskite structure. SEM micrographs showed dense microstructure with homogeneous distribution of grains of size ∼ 10 - 13 µm. CeO2 added BCZT ceramics showed high remnant polarization Pr ∼ 12 µC/cm2 and a low coercive field Ec ∼ 1.6 kV/cm compared to other BCZT-0.08 wt.% XO2 (X = Si4+, Ge4+ and Mn4+) ceramics. Excellent piezoelectric properties (d33 ∼ 675 pC/N, g33 ∼ 14 mV.m/N, and kp ∼ 60%) were observed for the CeO2 added BCZT ceramics, which is the highest val...

Effect of poling process on piezoelectric properties of BCZT – 0.08 wt.% CeO2 lead-free ceramics

The properties of lead free piezoelectric materials can be tuned by suitable doping in the A and B sites of the perovskite structure. In the present study, cerium has been identified as a dopant to investigate the piezoelectric properties of lead-free BCZT system. BCZT – 0.08 wt.%CeO2 lead-free ceramics have been synthesized using sol-gel technique and the effects of CeO2 dopant on their phase structure and piezoelectric properties were investigated systematically. Poling conditions, such as temperature, electric field, and poling time have been optimized to get enhanced piezoelectric response. The optimized poling conditions (50°C, 3Ec and 30min) resulted in high piezoelectric charge coefficient d33 ~ 670pC/N, high electromechanical coupling coefficient kp ~ 60% and piezoelectric voltage coefficient g33 ~ 14 mV.m/N for BCZT – 0.08wt.% CeO2 ceramics.

Influence of cation distribution on the magnetic and dielectric properties of Zn doped CFO ceramics

Cations site registry of Co1-xZnxFe2O4 (0 ≤ x ≤ 0.3) ceramics, synthesized by combustion method, has been estimated using Mossbauer spectroscopic study and Rietveld analysis and its influence on the magnetic and dielectric properties have been studied. Decreased B-site hyperfine field with progressive Zn doping due to the occupancy of non-magnetic Zn ions in the tetrahedral site of CFO lattice has been observed in Mossbauer data. Magnetic moment of Co1-xZnxFe2O4 (0 ≤ x ≤ 0.3) calculated from the cation distribution estimated from the Mossbauer data has been compared with the experimentally observed magnetic moment. Decreased dielectric constants (e′) with increasing Zn concentrations, in the frequency range 20Hz - 1MHz (at ~300K), indicates increased Fe+3 concentrations in the octahedral sites. The temperature dependent dielectric data showed a progressive reduction in the magnetic transition temperature (TC) from 528˚C for x = 0 to 422˚C for x = 0.3 of the Co1-xZnxFe2O4 (0 ≤ x ≤ 0.3) samples. Increasing ...

Investigation of magneto-electric properties of BCZT-NFO particulate composite

:Synthesis and characterizations for ferroelectric, ferromagnetic properties of 50BCZT - 50NFO particulate composite have been investigated. Phase pure BCZT (tetragonal) and NFO (cubic inverse spinel) have been observed in powder XRD pattern of 50BCZT-50NFO composite. Average grain size of 12µm for BCZT and 4µm for NFO have been observed in the back scattered electron diffraction (BSE) image of the sintered sample. Hysteresis loop measurement reveals typical ferroelectric nature of the sample with remnant and saturation polarizations of 8.34µC/cm2 and 17.4µC/cm2, respectively. Furthermore, sintered BCZT-NFO sample also showed good ferromagnetic M-H hysteresis loop with saturation magnetization upto ~14.6emu/g. Magnetostriction measurements showed a value of ~ - 20ppm for pure NFO and ~ - 8ppm for the composite.