Rekha Rani

Ferroelectric Properties of Microwave Processed PZT-NiZn Ferrite Composites

Being materials with a large number of interesting properties, ferroelectric-ferrite based composites have recently been developed. People are showing a great interest in these materials due to some unique properties like magnetoelectric effect in addition to the ferroelectric, dielectric and magnetic properties. After a review of literature it is found that the variation in different properties of PZT ceramics is found to depend on the amount of ferrite content. In this paper, we are reporting the variation in ferroelectric properties of PbZr0.65Ti0.35O3 (PZT) by varying Ni-Zn ferrite (NZF) content. The studied system having compositional formula (1-x) PZT–x NZF (0 ≤ x ≤ 0.025, in steps of 0.005), was prepared by solid state route using microwave sintering. Remanant polarization was found to be monotonically decreasing with increasing ferrite content as observed from the recorded P-E hysteresis loops for all the samples at 20 Hz. Microwave sintering results in significant improvements in properties as compared to conventionally sintered samples.

Dielectric, ferroelectric and ferromagnetic properties of x Ni0.8Zn0.2Fe2O4-(1-x) Pb0.99La0.02Zr0.65Ti0.35O3 composites

For the present study, two phase ceramic (ferroelectric-ferrite) composites using La substituted lead zirconate titanate (PLZT) and Ni-Zn ferrite (NZF) with compositional formula x Ni0.8Zn0.2Fe2O4-(1-x) Pb0.99La0.02Zr0.65Ti0.35O3 (x = 0, 0.05, 0.10 and 0.15) were synthesized by conventional solid state reaction route. From X-ray analysis, it was confirmed that no chemical reaction took place between individual phases. Dielectric properties were studied as a function of temperature and frequency. Decrease in dielectric constant and increase in dielectric loss was observed with increasing ferrite content. Anomalous behavior in paraelectric region was observed for all the composite samples (x = 0.05, 0.10 and 0.15) at low frequencies. To study ferroelectric and ferromagnetic properties, P-E and M-H hysteresis loops were recorded respectively. Effect of electric field on magnetization was studied for all composite samples to confirm magnetoelectric coupling.

Ferroelectric, Magnetic and Magnetoelectric Properties of Ferroelectric Rich Ni0.8Zn0.2Fe2O4-PbZr0.65Ti0.35O3 ME Composites

Magnetostrictive-piezoelectric (magnetoelectric) composites using magnetostrictive nickel zinc ferrite (NZF) and piezoelectric lead zirconate titanate (PZT) having compositional formula yNi0.8Zn0.2Fe2O4-(1-y)PbZr0.65Ti0.35O3 (0 ≤ y ≤ 0.15 in the steps of 0.05) were synthesized by conventional solid state method. Room temperature P-E and M-H hysteresis loops were recorded to study ferroelectric and magnetic properties of composites respectively. Effect of electric poling on values of remanant magnetization (Mr) and saturation magnetization (Ms) was studied for all composite samples (y = 0.05, 0.10 and 0.15) to confirm magnetoelectric (ME) coupling. ME coefficient (dE/dH) was measured as a function of dc magnetic field for all composite samples.

Dielectric Properties of 0.95 (Pb−/LaZr.Ti.O)-0.05(Ni.Zn.FeO) Composites

We report studies on dielectric properties of magnetoelectric composites of La-substituted lead zirconate titanate (PLZT) and zinc-doped nickel ferrite (NZF) with compositional formula 0.95 Pb1-3x/2LaxZr0.65Ti0.35O3-0.05 Ni0.8Zn0.2Fe2O4 (𝑥=0, 0.01, 0.02, and 0.03). The materials were synthesized by conventional solid state reaction route. The presence of individual phases (PLZT and NZF) was confirmed by using X-ray diffraction technique. Dielectric properties were studied as a function of temperature and frequency. Significant improvement was observed in dielectric properties with addition of La.

A comparative study of conventionally sintered and microwave sintered nickel zinc ferrite

For the present work, nickel zinc ferrite having compositional formula Ni0.8Zn0.2Fe2O4 was synthesized by conventional solid state method and sintered in conventional and microwave furnaces. Pellets were sintered with very short soaking time of 10 min at 1150 °C in microwave furnace whereas 4 hrs of soaking time was selected for conventional sintering at 1200 °C. Phase formation was confirmed by X-ray diffraction analysis technique. Scanning electron micrographs were taken for microstructural study. Dielectric properties were studied as a function of temperature. To study magnetic behavior, M-H hysteresis loops were recorded for both samples. It is observed that microwave sintered sample could obtain comparable properties to the conventionally sintered one in lesser soaking time at lower sintering temperature.

Ferroelectric Properties of La Substituted PZT Ceramics

For the present study, La substituted PZT ceramics having compositional formula Pb1−3x/2LaxZr0.65Ti0.35O3 were prepared by conventional solid state method. La content was varied from x = 0 to 0.03 in the steps of 0.01. XRD analyses of all the samples were done and were found to have single phase with rhombohedral structure. In this paper, we are reporting the variation in ferroelectric properties of Pb1−3x/2LaxZr0.65Ti0.35O3 by varying La content. P‐E hysteresis loops were recorded using P‐E loop tracer based on Sawyer‐ Tower circuit for all the samples at 20 Hz. Increase in coercive field (Ec), remanant polarization (Pr), saturation polarization (Ps) and squareness ratio (Pr/Ps) was observed with increase in x.

Effect of two-stage sintering on dielectric properties of BaTi0.9Zr0.1O3 ceramics

The effect of two-stage sintering on the dielectric properties of BaTi0.9Zr0.1O3 ceramics prepared by solid state route was investigated and is presented here. It has been found that under suitable two-stage sintering conditions, dense BaTi0.9Zr0.1O3 ceramics with improved electrical properties can be synthesized. The density was found to have a value of 5.49 g cc−1 for normally sintered samples, whereas in the case of the two-stage sintered sample it was 5.85 g cc−1. Dielectric measurements were done as a function of frequency and temperature. A small decrease in the Curie temperature was observed with modification in dielectric loss for two-stage sintered ceramic samples.