Structural, Electrical and Optical Study of ‘A’ Site Deficient Heterovalent Ion Doped Barium Zirconium Titanate Perovskite

In view of the processing and environmental issues pertaining to lead based ferroelectric materials, investigations on lead free ferroelectrics are carried intensively in recent years. These materials are interesting because, they are flexible with respect to structural changes and functional properties. These materials have potential device applications such as capacitors, sensors, actuators, and memory storage and microwave devices. This thesis is an attempt to elucidate the effect of substitution of heterovalent ions (Bi, Y, Dy) on the ‘A’ site of Barium Zirconium Titanate BaZr0.25Ti0.75O3 (BZT) pervoskite. Their structural, morphological, electrical and optical properties are investigated. The XRD study on the ceramic compositions showed single phase cubic perovsite structure at room temperature

Microstructural analysis of neutron-irradiation induced changes in polyester fibre studied using EPMA

Electron microscopy is an important characterization technique for the study of textile fibre as it gives more information on fabric wear, nature of fibre fracture, chemical degradation, abrasion, fatigue and many others. Electron Probe Micro Analyzer (EPMA) micrographs of virgin and some neutron-irradiated samples (graphite coated) are discussed. The filament diameter, D, of virgin PET fibre obtained from EPMA study was 12.5 µn. The surface topography of single filament distinctly reveals the core and sheath parts of the filament. The core diameter of the virgin fibre was estimated to be 1.43 µm. The fibre irradiated at fluence 1 × 1012 n/cm2 shows radiation induced sphere like polymer balls or spherulites of diameter 2.27 µm in the expanded core region. Due to irradiation, the sheath area crosslinks with expanded core region, which may be responsible for increase of strength and hardness of the polymer materials. Moreover, the micrograph at 3000 X magnifications clearly shows that there is no preferred orientation of the polymer in any direction confirming the isotropic nature of the sample.Microstructural analysis of neutron-irradiation induced changes in polyester fibre studied using EPMA Biswajit Mallick1*, Ramesh Chandra Behera2, Simanchal Panigrahi1, Tanmaya Badapanda1, Biswanath Parija1, Banita Behera1, Manas Panigrahi1 and Madhumita Sarangi2 1Department of Physics, National Institute of Technology, Rourkela-769 008, Orissa, India 2Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela-769 008, Orissa, India E-mail : [email protected] of Physics, National Institute of Technology, Rourkela-769 008, Orissa, India 2Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela-769 008, Orissa, Indi

Structural and electromechanical study of Bi0.5Na0.5TiO3-BaTiO3 solid-solutions

Solid solution of (1-x)Bi0.5Na0.5TiO3–xBaTiO3 have been synthesized via conventional solid-state reaction route. Structural changes of the solid-solutions were investigated by using X-ray diffraction, Rietveld refinement Raman spectroscopy and piezoelectric studies. X-ray diffraction analysis shows a distinct 002/200 peak splitting appearing at x = 0.07 showing the coexistence of rhombohedral and tetragonal phase. Raman spectroscopy shows a splitting of (TO3) mode at x = 0.07 confirming the presence of the morphotropic phase boundary region. The dominant bands in the Raman spectra are analysed by observing the changes in their respective peak positions, widths and intensities as the x increases. The piezoelectric properties of the solid solution increase with rise in BaTiO3 content and shows optimum value at x = 0.07 owing to the co-existence of two ferroelectric phases. Based on these results, it is suggested that the morphotropic phase boundary in the studied system lies in the composition x = 0.07

Effect of yttrium doping in barium zirconium titanate ceramics: A structural, impedance, modulus spectroscopy study

In the current article, we studied the effect of yttrium [Y3+] ions' substitution on the structure and electric behavior of barium zirconate titanate (BZT) ceramics with a general formula [Ba1-x Y 2x/3](Zr0.25Ti0.75)O3 (BYZT) with [x = 0, 0.025, 0.05] which were prepared by the solid-state reaction method. X-ray diffraction patterns indicate that these ceramics have a single phase with a perovskite-type cubic structure. Rietveld refinement data confirmed [BaO 12], [ZrO6], [TiO6], [YO6] clusters in the cubic lattice. The Y3+ ions' effects on the electric conductivity behavior of BZT ceramics as a function of temperature and frequency are described, which are based on impedance spectroscopy analyses. The complex impedance plots display a double semicircle which highlights the influences of grain and grain boundary on the ceramics. Impedance analyses showed that the resistance decreased with the increasing temperature and resulted in a negative temperature coefficient of the resistance property in all compositions. Modulus plots represent a non-Debye-type dielectric relaxation which is related to the grain and grain boundary as well as temperature-dependent electric relaxation phenomenon and an enhancement in the mobility barrier by Y3+ ions. Moreover, the electric conductivity increases with the replacement of Ba 2+ by Y3+ ions may be due to the rise in oxygen vacancies. © 2013 The Minerals, Metals & Materials Society and ASM International