Dielectric Properties of Nanostructured PZTSynthesised by Chemical Methods

In this study, the dielectric behaviour of smart material, lead zirconate tiatanate (PZT), whichis important for wide industrial applications, has been explored. Two samples of nanostructuredPb(Zr0.52Ti0.48)O3 ceramic powders were prepared by hydroxide co-precipitation and aqueoussolution method (water bath technique). The XRD pattern of the  powder exhibited the presenceof major tetragonal and minor rhombohedral crystalline phases indicating the mixed-phasecomposition, which is close to the morphotropic phase boundary (MPB). SEM analysis revealedgood homogeneity of the materials. The plot of real part versus imaginary part of the compleximpedance was observed nearly a semicircle, indicating that the samples are good dielectricmaterials, whose resistance decreases considerably with the increase of temperature. Similar tothe normal ferroelectric materials, the dielectric constant () of PZT has been found to be increasinggradually with temperature and attains a maxima (max). The detailed analysis for the shift in peaktemperature and dielectric constant were carried out

Simulation and Comparison of Three and Nine level Cascaded H-bridge Multilevel Inverter

The multilevel inverter was developed as a solution to increase the converter operating voltage above the voltage limits of classical semiconductors. The function of the multilevel inverter is to synthesize a high voltage waveform from several lower levels of dc voltages. If the switching angle arrangement technique is not selected properly then the total harmonic distortion of voltage output waveform may become unacceptable. In this paper the sinusoidal pulse width modulation (SPWM) control strategy is used to control output voltage. In this paper simulation of single phase three and nine level cascaded H-bridge multilevel inverter is performed in Simulink environment. The comparison of THD values of these inverters is done

Synthesis of Ultrafine SrFe12O19 Particles with High Coercivity

Ultrafine particles of SrFe12O19 have been synthesized by citrate precursor technique. Solid state reactivity studies of citrate precursor lead to the formation of fine particles of SrFe12O19 below 823K. The size and morphology of these particles were studied by SEM. The surface area measured by BET method for5.2nm crystallite is found to be 27.45 m2/g. having particle size 42nm. Ultrafine particles of SrFe12O19 shows interesting magnetic properties which differs from conventional particles and are measured by VSM. The intrinsic coercive force of 6500Oe is observed for ultrafine SrFe12O19 which is close to the theoretical limit and is one of the highest value reported so-far for isotropic SrFe12O19 having 16.5.nm crystallite size. The Tc value for ultrafine particles is found to be around 830K which is larger than the reported value of 748K for bulk materials. Mossbauer spectroscopy have ben explored to study these fine particles for non-collinear spin structure predominantly at the surface compared to the core of the particule