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Characterization of both uncalcined and calcined eggshells was done in this work. Raw eggshells turned out as a good source of calcite phase. Calcined eggshells had a mixture of lime and portlandite phase. A significant impact of calcination temperature on the percentage of generated phases was observed. Qualitative as well as semi-quantitative phase analysis, morphological characterization and physical property estimation was done for the produced powder. The influence of synthesized raw material on soil stabilization and biomaterial formation was further assessed. The eggshell turned out as a potential source of raw material for various sectors. Keywords: eggshell, calcination, true density, plasticity index, hydroxyapatite. Resumo A caracterização de cascas de ovo não calcinada e calcinada foi feita neste trabalho. A casca de ovo mostrou-se uma boa fonte de

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In this work, BaTiO3, Ba(Mg0.01Ti0.99)O3, Ba(Mg0.015Ti0.985)O3, Ba(Mg0.02Ti0.98)O3 and Ba(Mg0.01Zr0.15Ti0.84)O3 ceramics have been prepared through conventional solid-state route to investigate the effects of Mg2+ and Zr4+ dopants as mono-substitution (only Mg2+) and co-substitution (Mg2+ and Zr4+) of B-site on the structural, electrical and optical properties of BaTiO3 ceramics. Exhibiting perovskite structure, Ba(Mg x Ti1−x)O3 ceramics revealed a decrement pattern of tetragonality with the increment of the concentration of MgO which was confirmed through Rietveld analysis. Morphological analysis of the sintered samples by scanning electron microscope showed a grain growth retardation phenomenon with Mg2+ addition. Releasing from this retardation process, Ba(Mg0.01Zr0.15Ti0.84)O3 showed a maximum dielectric constant of ∼1269.94 due to the enhanced domain wall motion and the confinement within the solubility limit of Mg2+. The ferroelectric characteristic of Ba(Mg x Ti1−x)O3 was sluggish due to the effects of grain size and its boundary. The optical band gap for BaTiO3 was found to be decreased from 3.55 eV to 3.06 eV with the addition Mg2+ content but for Ba(Mg0.01Zr0.15Ti0.84)O3, the value increased due to the Burstein-Moss effect. Again the FTIR analysis proved that no impurity phases were formed during the doping phenomenon, but in Ba(Mg x Ti1-x)O3 ceramics, a significant reduction of Ti-O bond strength was observed. However, BaTiO3, Ba(Mg0.01Ti0.99)O3, Ba(Mg0.015Ti0.985)O3 and Ba(Mg0.02Ti0.98)O3 ceramics had manifested P-E loop having lower remanent polarization and coercive field compared to Ba(Mg0.01Zr0.15Ti0.84)O3 ceramics with moderate electrical and optical properties. So, co-doping with Mg2+ and Zr4+ evidenced a favorable accession for the increment of the properties of BaTiO3 ceramics.

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The research was done to understand the influence of nano-sized donar dopant incorporation in barium titanate (BTO) structure. Core-shell structures are stated to form while dopants are added directly to BTO. Low diffusivity of ions in solid state results such core-shell structures. Pure BTO was doped with different concentration of niobium oxide (Nb 2 O 5 ) (0.2, 0.3 and 0.4 mol %). Single stage sintering at 1250°C, 1275°C and 1300°C was initially chosen. Soaking time was varied from 0 to 2 hours. Sintered samples were taken for further characterization. Percent theoretical density (%TD) of the sintered samples was measured. Microstructure of the sintered samples was revealed by Scanning Electron Microscope (SEM). Both temperature and frequency dependent dielectric property was measured using impedance analyzer. X-ray diffraction (XRD) and Differential Thermal Analysis (DTA) was also performed. XRD confirmed the diffusion of Nb 5+ ions into the BTO lattice. While impedance analyzer and DTA proved the shifting of Curie temperature (T C ) from ~120°C to ~71°C. Enhanced dielectric property was observed by the addition of Nb 2 O 5 .

Abstract:The work was done to understand the effects of naturally occurred bone and teeth ash on the physical as well as mechanical properties of bone china products. Both bone and teeth ash was prepared following conventional thermal decomposition method. Locally found cattle bones and tooth was utilized for this purpose. Three different routes of powder or ash preparation i.e. boiling-wood firing, excavating-calcination and boiling-calcination were followed. The calcination temperature was fixed at 950°C-2 hours. After that, density and phase identification of ash was carried out. Finally, bone china product was manufactured using powder compaction and slip casting route. Firing was done at a constant temperature (1150°C-2 hours). Further characterizations (density, percent firing shrinkage, percent water absorption and modulus of rupture measurement) of the sintered samples were evaluated. Boiling-calcination route was found to be the most superlative route. However, enhanced properties of bone china were obtained by the addition of teeth ash.

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