S. Asad Ali

Microstructural, optical and dielectric properties of La0.8Ba0.2FeO3 nanostructures synthesized by sol-gel combustion method

Barium doped lanthanum ferrite (LaFeO3) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 700°C. Microstructural studies were carried by XRD and SEM techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible technique. The energy band gap was calculated and obtained 3.01 eV. Dielectric properties characterized by LCR meter and have been observed appreciable changes. The observed behavior of the dielectric properties can be attributed on the basis of Koop’s theory based on Maxwell-Wagner two layer models in studied nanoparticles.

Synthesis and characterization of electron doped La0.85Te0.15MnO3 thin film grown on LaAlO3 substrate by pulsed laser deposition technique

We report the structural, morphological and magneto-transport properties of electron doped La0.85Te0.15MnO3 (LTMO) thin film grown on (001) LaAlO3 single crystal substrate by pulsed laser deposition (PLD). X-ray diffraction (XRD) results confirm that the film has good crystalline quality, single phase, and c-axis orientation. The atomic force microscopy (AFM) results have revealed that the film consists of grains with the average size in a range of 20–30 nm and root-mean square (rms) roughness of 0.27nm. The resistivity versus temperature measurement exhibits an insulator to metal transition (MIT). We have noticed a huge value of magnetoresistance (∼93%) close to MIT in presence of 8T field. X-ray photoemission spectroscopy confirms the electron doping and suggests that Te ions could be in the Te4+ state, while the Mn ions stay in the Mn2+ and Mn3+ valence state.

Dielectric response of polyethersulphone (PES) polymer irradiated with 145 MeV Ne6+ ions

Heavy ion irradiation produces modifications in polymers and adapts their electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission and formation of carbon rich clusters. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Polyethersulphone (PES) polymer film is carried out. 250 μm thick PES films were irradiated to the fluences of 1012 and 1013 ions/cm2 with Ne6+ ions of 145 MeV energy from Variable Energy Cyclotron Centre, Kolkata On irradiation with heavy ions dielectric constant (e′) decreases at higher frequencies and increases with fluences. Variation of loss factor (tan δ) with frequency for pristine and irradiated with Si ions reveals that tan δ increases as the frequency increases. The tanδ also increases with fluence. Tan δ has positive values indicating the dominance of inductive behavior.