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[en] The fractal characteristics of nano-sized powders of CeO2-YO1.5 solid solutions, prepared by combustion synthesis and calcined at various temperatures, have been investigated by small angle X-ray scattering technique. Results show a mass-fractal behavior for the powders with mass-fractal dimension Dm in the range 2.2-2.6. The estimated particle radii are in the range of 4-15 nm, which is in close agreement with TEM results. For the powders calcined at higher temperatures, the particle interface has a tendency to become rough with a significant growth in the particle size and polydispersity
Journal
[en] In search of environment-friendly piezoelectric ceramics, we have modified lead-free sodium bismuth titanate (Na1/2Bi1/2TiO3: NBT) by making solid solution with NaNbO3. In NBT, a small deviation in A-site or B-site cation stoichiometry affects the conductivity by significant magnitude which is believed to originate mostly from oxygen ion migration. In NBT-NaNbO3 (NBT-NN) solid solution, the excess sodium concentration lowers the deficiency and likely to show sizable impact on the conductivity. Hence, structural point of view, it would be interesting to find if the electrical conductivity of NBT has a contribution from Na+ ions along with from known oxygen ions. Our findings in this study would help to understand the structure property correlations in NBT and throw a light on possible usage as a potential ionic conductor in addition to piezoelectric applications. In this work, we have carried out a detailed structural study of NBT-NNx (x = 0.05) using powder X-ray diffraction in the temperature range 12 to 900 K. Rietveld refinements revealed that both the ferroelectric and antiferrodistortive phase transitions occur together at 623 K accompanied by change in crystal structure from initial rhombohedral phase (space group: R3c) to high temperature cubic phase (space group: Pm-3m). This indicates the suppression of intermediate tetragonal phase of pure NBT
Source
Dutta, Dimple; Sharma, Pramod; Sawant, Shilpa N.; Barick, K.C.; Gupta, Vinita G.; Hassan, P.A. (Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India)) (eds.); Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Society for Materials Chemistry, Mumbai (India); 456 p; ISBN 978-81-953520-3-6; 
; Jun 2021; p. 232; ISMC-2020: 8. DAE-BRNS interdisciplinary symposium on materials chemistry; Mumbai (India); 17-19 Jun 2021
; Jun 2021; p. 232; ISMC-2020: 8. DAE-BRNS interdisciplinary symposium on materials chemistry; Mumbai (India); 17-19 Jun 2021
[en] The topics covered in this proceedings are invited talks, tutorials on neutron scattering techniques, phonon physics, electron states and electronic properties, magnetism and magnetic properties, semiconductor physics, physics of defects and disordered materials, transport properties, superconductivity and superfluidity, liquids, liquid crystals and plastic crystals, phase transitions and critical phenomena, surface and interface physics, non-equilibrium phenomena in solids, resonance studies and relaxation phenomena, neutron scattering techniques, computational condensed matter physics and solid state devices, techniques and instrumentation. Papers relevant to INIS are indexed separately
Source
Jul 2003; 670 p; Allied Publishers Pvt. Ltd; Mumbai (India); 45. DAE solid state physics symposium; Chandigarh (India); 26-30 Dec 2002; ISBN 81-7764-484-X;
[en] The high-energy Mono-Laue technique has been used to explore its suitability to obtain diffuse x-ray scattering data which is used to study the short range order characteristics associated with order-disorder phase transitions in binary metallic alloys. A heater assembly has been constructed and the experiments were performed on Cu3Au, Cu3Pd and Ni-Al single crystals using the synchrotron source at DESY, Hamburg. Results are discussed. (author)
Source
Chaplot, S.L.; Krishna, P.S.R.; Sakuntala, T. (Solid State Physics Div., Bhabha Atomic Research Centre, Mumbai (India)) (eds.); Board of Research in Nuclear Sciences, Dept. of Atomic Energy, Mumbai (India); 713 p; ISBN 81-7319-486-6; ; 2002; p. 3-4; 44. DAE solid state physics symposium; Mumbai (India); 26-30 Dec 2001; 3 refs., 5 figs.
; 2002; p. 3-4; 44. DAE solid state physics symposium; Mumbai (India); 26-30 Dec 2001; 3 refs., 5 figs.
[en] The structure of nano-sized powders of indium sulfide (In2S3) and gallium sulfide (Ga2S3), prepared by single source precursor route has been investigated by small angle X-ray scattering technique. The particle morphology shows interesting fractal nature. For In2S3, the nanoparticle aggregates show a mass fractal with fractal dimension 2.0 that increases with longer time of thermal treatment. Below the length scale of about 20 nm, the particles have a rough surface with a surface fractal dimension of 2.8. Unlike In2S3, structure of Ga2S3 exhibits a single surface fractal over whole q-range of study. The estimated particle sizes are in range of 5-15 nm and the results are supported by transmission electron microscope.
Journal
[en] We report the results of temperature-dependent powder X-ray diffraction studies on lead-free piezoelectric sodium bismuth titanate (NBT) modified by partially substituting Ba at the A site or Nb at the B site. We observed the disappearance of certain reflections and a change in the main perovskite peaks of the rhombohedral phase suggesting a structural phase transition. Detailed Rietveld refinements revealed that both the ferroelectric and the antiferrodistortive phase transitions occur together at high temperature leading to a change in crystal structure from the low-temperature ferroelectric rhombohedral phase (space group: R3c) to the high-temperature paraelectric cubic phase (space group). This suggests the suppression of the intermediate tetragonal phase of pure NBT. We found that substituting Ba onto the A site enhances the lattice strain and lowers the antiferrodistortive phase transition temperature.
Journal
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