[en] The topics covered in this symposium include phase transitions, soft condensed matter (including biological systems), nano materials, experimental techniques-instrumentation and solid state devices, superconductivity, magnetism, electronic structure and phonons, semiconductor physics, transport properties, surface - interface and thin films, liquids, glasses and amorphous systems, etc. Thus it would be appropriate to say that these proceedings fairly accurately reflect an update on the research activities in solid-state physics being pursued in universities and national laboratories in India

[en] The purpose of this talk is to present a brief overview of the discoveries in relation to PZT and PMN-xPT in which the use of multiple diffraction probes (x-ray, electron, neutron diffraction) in conjunction with the physical property measurements has played crucial role in establishing the structure and the stability fields of the newly discovered monoclinic phases. The implications of these discoveries on the high piezoelectricity of the MPB ceramics are discussed

[en] This thesis present the structural changes and enhancement of superconducting and flux pinning properties due to modification of Bi₂Sr₂Ca₁Cu₂O_y (Bi-2212) system by different rare earth (RE) additions and substitutions at its different cationic sites. The co-doping effect of Pb and RE in Bi-2212 is also studied. The enhancement of superconducting and flux pinning properties are due to the decrease in hole concentration, structural modifications and defects created by the co-doping of Pb and RE in Bi-2212 superconductor. (author)

[en] In the present thesis work, We have improved the magnetoresistance properties of La_1-xA_xMnO₃ (A=Sr, Ca) perovskite manganites and Sr₂FeMoO₆ double perovskite at low value of magnetic field (∼3 kOe) by modifying their grain boundaries. An enhancement in magnetoresistance is observed up to ∼94% in manganites and ∼38% in double perovskite at low field (∼3 kOe), which is encouraging with regard to the potential applications. (author)

[en] Zirconium based alloys have attracted a great deal of attention for their substantial hydrogen storage capacity. But the high stabilities of these hydrides as indicated by their ΔH values make their practical use very limited. The present thesis deals with the study of partial substitution of Zr and Fe elements in ZrFe₂ compound by other elements i.e. Mn, Ni, Cr, Co to increase the equilibrium pressure and thus to reduce the stability of their hydrides. Another purpose of this study is to obtain knowledge of structural and magnetic characteristics of the alloys and relevant hydrides. Another phase of this thesis deals with the thin film hydrogen storage. The use of thin film for hydrogen storage has become very important as the main process of absorption/desorption of hydrogen takes place on the surface of the material and thin film provide a large surface area for hydrogen absorption. Here the effect of hydrogen absorption on Zr/M (M = transition metals) bilayer system has been studied in terms of their resistance. (author)

[en] Full text: We have investigated the effect of nanometric grain size on electrical-, magneto-transport magnetic and magneto-impedance behaviors of series of chemically synthesized nanocrystalline, single- phase granular La_0.7Sr_0.3MnO₃, La_0.5Gd_0.2S_0.3rMnO₃, La_0.7Ca_0.3MnO₃ and Nd_0.7Sr_0.3MnO₃ samples having an average grain size in the nanometric regime (14 - 28 nm). Based upon a spin-polarized tunneling mechanism, we have proposed a phenomenological model to explain the observed electronic behavior. Most interestingly, magneto-transport measurements show that the magnitude of low-field magnetoresistance, as well as high field magnetoresistance remains constant up to sufficiently high temperature (∼220 K) and then drops sharply with temperature. This strange temperature dependence of MR is decided predominantly by the nature of the temperature response of surface magnetization of nanosize magnetic particles. Magnetization study on La_0.5Gd_0.2Sr_0.3MnO₃, nanoparticles (∼20 nm) reveal super -paramagnetic phase associated with this system. Doping of Gd on La sites and its anti ferromagnetic coupling with Mn lattices induce random magnetic disorder in the magnetic lattice of the system. However, the magnetic properties of this system are mainly decided by its nano dimension. We have also investigated the effect of nanometric grain size (φ = 14 - 28 nm) modulation on the behavior of magneto-impedance (MI) La_0.7Sr_0.3MnO₃ (LSMO) manganites at room temperature. MI measurements were carried out in the ac signal frequency (f) range of 40 kHz - 110 MHz in presence of applied dc magnetic field (H) in the range of 0 - ±2.5 kOe, respectively. The experimental results show that MI % increases with the increase in nanometric grain size (φ) for this series of samples. This behavior can be explained in the light of classical electrodynamics, which relates this effect with the dependency of skin depth on external magnetic field and applied ac signal frequency. Interestingly, MI of about 92 % was obtained for the 28 nm LSMO sample at a frequency (f) of 10 MHz and at H 2.5 kOe. The same sample also showed maximum MI sensitivity of about 1% / Oe near 60 Oe dc magnetic field at f = 10 MHz. Epitaxial LSMO grains grown on slightly lattice mismatched substrate showed strong substrate-induced strain dependent transport and magnetic behaviors, exhibiting strong correlation with Jahn-Teller strain. (author)

[en] High pressure Raman and x-ray diffraction studies on lanthanum hafnate upto pressures of 65 GPa and 30 GPa indicate that beyond 10 GPa it starts disassociating into its high pressure oxides and this process is complete only beyond 30 GPa. These oxides were found to become structurally disordered at 65 GPa. (author)

[en] High pressure behavior of ZrGeO₄ is investigated by Raman spectroscopic technique. Under the application of pressure, the frequency of the GeO₄ librational mode decreases while all the other Raman modes show normal behavior. Soft librational mode has been observed experimentally in the case of other ABX₄ compounds such as CaWO₄, SrWO₄. In the case of YLiF₄ simulations have indicated soft E_2g phonon associated with LiF₄ librations prior to the scheelite-fergusonite transition. The present results point towards dynamical instability of the ZrGeO₄ scheelite structure, and the possibility of transition to a fergusonite-type phase. (author)

[en] Angle Resolved Photo-Electron Spectroscopy (ARPES) is a powerful tool for the determination of band structures and mapping of Fermi-surfaces of crystalline solids. Optical design of an ARPES beamline working over a very wide energy range (10 eV- 4000 eV) is described on the high brightness and low divergence Indus-2 synchrotron radiation source. A toroidal analyzer will be developed for simultaneous measurement of kinetic energy and angular distribution of photo-electrons. Initially, the beamline will be installed on a bending magnet and eventually on an insertion device like an undulator. The beamline uses mirrors, asymmetric crystal/grating in reflection mode for a monochromator, vacuum lines and auxiliary systems. Micro-size focusing is achieved with the help of a pair of spherical mirrors in the Kirkpatrik-Baez. (K-B) arrangement. In this paper we describe the design features and ray tracing results of ARPES branch of the beamline using SHADOWVUI 2.1 and XOP 2.1 softwares. (author)

[en] Using an ab-initio calculation we provide here a unified study of structural, electronic and phonon properties for the noble nitride PtN by using Quantum-espresso code. The present study is used to determine the most possible crystal structure of the PtN and with present study it is suggested that the zinc blende, structure is most probable for the compound PtN. The calculated elastic properties and zone center phonon modes calculated in the present study are in general good agreement with the available data. (author)