P. K. Sinha

Synthesis and characterization of Fe3+-modified PLZT ferroelectrics

Fe3+-modified nanocrystalline PLZT, i.e., Pb0.92[La1−zFez]0.08[Zr0.60Ti0.40]0.98O3 (PLFZT) (z=0.0, 0.3, 0.6, 0.9, 1) materials were synthesized by a high-temperature solid-state reaction technique. X-ray studies of the compounds confirmed the formation of single-phase, ultrafine (nano-sized) and homogeneous materials. Microstructural scanning electron microscopy (SEM) study shows the uniform distribution of smaller grains on the surface of the samples. Detailed dielectric studies of the compounds as a function of temperature (30–450 °C) show that the broadening of the permittivity peak and transition temperature depends on Fe3+-ion concentration. Analysis of diffuseness (γ) of the broadened dielectric peaks of the materials gave its value between 1 and 2, indicating the different degrees of substitutional disorder in the system. The increase in Fe3+-substitution at the La-site of PLZT shows many interesting and unusual dielectric relaxor behaviors of the compounds. The transition temperature Tc of PLZT (8/60/40) ferroelectric shifts towards a higher temperature region on increasing Fe3+ concentration. The variation of d.c. and a.c. electrical conductivity of the material with temperature shows its semiconducting behavior; and hence the materials can be used for some electronic devices.

Effect of Ga+ 3-ion Substitution on Structural, Dielectric and Electrical Properties of PLZT Ceramics

Polycrystalline samples of [Pb0.92 (La1 − zGaz)0.08][Zr0.60Ti0.40]0.98O3 (z = 0.0, 0.3, 0.6, 0.9, 1) were synthesized using a solid-state reaction route. X-ray/SEM studies show the formation of homogeneous and single-phase materials of small crystallite size (10 nm) in tetragonal structure. Temperature and frequency dependent dielectric permittivity and loss tangent show that the compounds have ferroelectric diffuse phase transition. Piezoelectric strain coefficient d33 of the Ga-substituted compounds at 26°C and 100 Hz was found to be 385, 181, 152, 168 and 172 pC/N for z = 0.0, 0.3, 0.6, 0.9 and 1 respectively. Both the ac and dc conductivity were studied over a wide range of temperature at fixed electric field (60 V/cm). The activation energy of the compounds was found in the range of 0.5–0.8 eV. The temperature variation of dc resistivity at a constant electric field (60 V/cm) showed the semiconductor characteristics of the materials in the high temperature range.

Effect of Sb+3-Ion Incorporation on Structural, Dielectric and Electrical Properties of Sol-Gel Derived Smart Material PLZT

Antimony (Sb+3 ) modified PLZT were prepared through a sol-gel technique with a general formula, Pb 0.92 (La 1−z Sb z ) 0.08 (Zr 0.60 Ti 0.40 ) 0.98 O 3 ; z = 0.0, 0.6, and 1.0 (PLSZT) formula to investigate the change in physical parameters of PLZT on substitution of Sb+3 at La-sites. To confirm the formation of the compounds XRD data have been taken on the gel dried calcined PLSZT powder. The dielectric and electrical properties of the compounds were studied by a complex impedance spectroscopic method (CIS). The effect of dopant (Sb) even in a small percentage has changed all physical properties of the PLZT drastically.