S.K. Pandey

Study of pinched loop characteristics of lead zirconate titanate (65∕35)

We report the effect of processing parameters such as (1) uniaxial and (2) isostatic pressings on ferroelectric behavior of lead zirconate titanate (PZT) having Zr∕Ti ratio 65∕35. The effect of temperature (−125–250°C) on pinched loop characteristics of uniaxially pressed PZT is also reported. Polycrystalline ceramic samples were synthesized by solid-state reaction technique and sintered at 1250°C. The density was estimated to be 7.63 and 7.58g∕cc for the uniaxially and isostatically pressed samples, respectively, prepared by conventional ball milling. X-ray diffraction analysis confirmed single phase formation with rhombohedral structure. All samples pressed uniaxially and isostatically showed pinched hysteresis loops at room temperature that disappear at higher temperatures. The remnant polarization (Pr) and coercive field (Eo) for the uniaxially pressed samples become well defined in magnitude and shape at higher measurement temperatures below phase transition temperature (Tc), but at low temperatures ...

Effect of Double Doping in Lead Zirconate Titanate (PZT) Lattices by Sol-Gel Technique for MEMS Applications

We report on the effect of double doping (La2+ and Sm3+) in PZT lattices in thin film form, keeping La (mol%) fixed at 8 mol% [Pb0.92-x La 0.08 Smx(Zr0.65Ti0.35)O3: x = 0, 0.02, 0.04, 0.06, 0.08]. Both the cation substitutions are being substituted at A site only. The thin films were grown on Pt/Si<111> substrates by sol gel technique. XRD diffractogram shows single phase for the films for x = 0.02. Thereafter, an unidentified phase starts appearing which increases with further substitution of Sm3+. Surface morphology was studied using atomic force microscope (AFM). The films show well-defined ferroelectric behaviour. The dielectric constant decreases with Sm substitution initially and then increases slowly as the Sm substitution is increased but never attains the pure PLZT (8/65/35) dielectric value. The loss tangent (tanδ) initially increases and then decreases. The phase transition temperature (Tc) increases drastically with 2 mol% Sm substitution and decreases slightly as the Sm substitution is increased further. The I-V behaviour shows a consistent shift towards the –ve bias voltage as the Sm substitution is increased from 2 mol% to 8 mol%. The logI-logV curve show ohmic behaviour with the electrode for all the samples. The P-E loop shows more hysteresis for the 2 mol% Sm substitution. The appearance of P-E loop qualitatively shows the piezoelectric nature of the films. Optical band gap was calculated from transmittance studies using a UV-Vis-NIR spectrophotometer. The optical band gap was estimated from (αhυ)2 vs hυ curve. The band gap decreases first with Sm substitution and then increases as the Sm substitution is increased. The results are discussed.

Ferroelectric Properties of Laser Ablated Sm Modified PCT Thin Films

Crystallized thin films of samarium modified lead calcium titanate ceramics with composition; Pb0.66Sm0.08Ca0.24Mn0.02Ti0.98O3 were deposited under different annealing and laser energy conditions. Thin films deposited at these conditions show a surface roughness, coercive field and remnant polarization in the range of 1.9–6.0 nm, 120–220 kV/cm and 4–11.5 μC/cm2, respectively. I-V and C-V measurements were also performed in order to study the electrical behaviour of the films.