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In the present work, lead-free SrTi0.85V0.15O3 ceramics was prepared by solid state reaction method. XRD and FESEM were used for the structural characterization. The XRD patterns of the prepared sample exhibit cubic structure with lattice parameter 3.904 A and also confirmed from Rietveld refinement. The average grain size calculated from the morphological analysis is 7.08 µm. The dielectric, impedance and electrical conduction mechanism of SrTi0.85V0.15O3 ceramics were investigated over a broad frequency range from 100 Hz to 5 MHz at different temperatures (563 – 663 K) and confirm all the properties are frequency and temperature dependent.

In this study, fluorescent carbon dots were prepared by the hydrothermal process and analysed the effect of nitrogen doping on the optical responses of the material. Doping introduces an excitation independent photoluminescence peak in the red region along with the excitation dependent shorter wavelength emission. The longer wavelength absorption and emission could arise from the modifications in the surface states which experimentally observed from the FTIR spectra. Time-resolved measurements indicate that the carrier lifetime delayed due to the doping. The modifications of the carboxyl and amine groups in the carbon dots introduce the considerable changes in the photophysics of nitrogen doped dots.

Porous mullite is widely used ceramic material in the industries. It has a combination of properties of mullite like high thermal and chemical stability, low thermal expansion coefficient and high creep resistance along with merit of the presence of pores (lightweight, high surface area). In the current article, an attempt has been made to prepare stoichiometric porous mullite using china clay (kaolinite) and aluminum hydroxide [Al(OH)3]. The effect of the addition of MoO3 on the porosity, strength and microstructure of the prepared porous mullite was also studied. Kaolinite is the aluminosilicate ceramic consist of (Si2O5)2- and [Al2(OH)4]2+ molecular sheets which decompose thermally to produce mullite. Kaolinite is rich in silica which prevents it to form stoichiometric mullite. Therefore, external alumina source is required to maintain 72wt.% alumina and 28wt.% silica. Thermal treatment at different temperature 1300°C, 1400°C and 1500°C was studied to achieve a product with higher apparent porosity with moderate flexural strength. The prepared mullite ceramic was characterized by X-ray diffractometer (XRD) and field emission scanning electron microscopy (FESEM) for the desired phase formation and to evaluate the morphology of the formed mullite grain. The1500°C sintered batch with 4wt.% additive shows apparent porosity of 36.11% and moderate flexural strength of 51.56 MPa. These results show the future perspective of the porous mullite in the field of catalyst support and adsorption.

Extended X-ray absorption fine structure (EXAFS) has been studied at the Cu K-edge in a copper mixed ligand complex, namely, [Cu(tmen)(acac)](ClO4) (complex I) (were tmen = tetramethylethylenediamine and acac = acetylacetonate). The crystallographic data of the complex I is not available, though it is known to have square pyramidal geometry. Survey of literature shows that crystal structure of an analogous complex, namely, [Cu(tmen)(acac)(H2O)](PF6) (complex II) is available. Tetramethylethylenediamine (tmen) and acetylacetonate (acac) are the common ligands in both the complexes I and II. The analogous complex II has Cu ion in square pyramidal geometry with acac and tmen ligands in the basal plane and H2O molecule in the axial site, O1 and O2 from acac and N1 and N2 from tmen form the square planar structure, O3 from H2O forms the axial site. Hence, the crystal structure of complex II has been used for generation of theoretical model. The theoretical model generated for the analogous complex II has been fitted to the experimental EXAFS data of complex I. The structural parameters for complex I have thus been determined. The values of these parameters have been reported and the coordination geometry of complex I has been depicted in a figure.

Mn and Co doped TiO2 thin films are prepared by rf magnetron sputtering technique. GIXRD measurements shows anatase phase for pure TiO2 and Mn doped TiO2, however mixed anatase and rutile phase for Co doped TiO2. XANES and EXAFS measurements at dopant and host site confirm the substitution of host site by dopant ions. O K edge measurements and EXAFS results at the dopant site confirms the presence of oxygen vacancies. Ferromagnetism obtained in the doped TiO2 thin films is attributed to the oxygen vacancy mediated interaction between the TM ions.

In current work, two different types of mullite ceramic powder were prepared using kaolinite and alumina by solid state and chemical precipitation route. The phases, bond types and microstructural evolution of the mullite powders were investigated by X-ray diffraction, infrared analysis, and field emission scanning electron microscopy to study the mullitisation behavior. The solid state method evident a pure mullite phase formation at 1550 °C. In case of chemical precipitation route small amount of alumina peak was noticed along with major phase of mullite which was also clearly apprehended from FESEM micrographs and IR spectra. Densification was more for the samples prepared by solid state process which may be correlated to the delayed mullitization process in chemical precipitation route.

Nanocrystalline ZnO thin films have potential for applications in variety of optoelectronic devices. In the present study, nanocrystalline thin films of ZnO are grown on fused silica substrate using electron beam (e-beam) evaporation technique. Phase identification is carried out using Glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy. Ultraviolet-Visible (UV-Vis) spectroscopic analysis is carried out to calculate energy band gap of the ZnO film. Surface morphology of the film is investigated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). Highly quality nanocrystalline thin films of hexagonal wurtzite ZnO are synthesized using e-beam evaporation technique.

Au@Pt core shell nanoparticles have been synthesized by reducing Au and Pt chloride precursors with Block Co-polymer and Ascorbic acid. The growth and nucleation of Au@Pt nanoparticles have been investigated by in-situ time resolved XANES measurement which gives the evolution of the reduction process of the precursors. Linear combination fitting of the XANES spectra has been carried out to find the fraction of Au and Pt cations reduced at a particular reaction time. UV-Visible spectroscopy is used as a complementary technique which gives the changes in the Au SPR peak as Au@Pt core shell nanoparticles are formed.

The band alignment of Zn0.9Co0.1O/ZnO thin film heterostructure was investigated using photoelectron spectroscopy. The ZnO, Zn0.9Co0.1O and Zn0.9Co0.1O/ZnO thin film heterostructure has been prepared using RF ion beam sputtering, The band offset of prepared heterostructure were calculated form valance band maximum and core level peaks. The valance band and conduction band offset for Zn0.9Co0.1O/ZnO heterostructure thin film were found to be 0.36 eV and 0.51 eV, respectively, which indicates type-II band alignment in the Zn0.9Co0.1O/ZnO heterostructure.

A computer-controlled flow setup has been designed and implemented at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 SRS which facilitates in situ time-resolved X-ray Absorption Spectroscopy (XAS) measurements on reactions carried out under specialized experimental conditions. The set-up has been tested by in-situ time resolved X-ray near edge structure (XANES) measurement on the evolution of the reduction process during synthesis of Cu nanoparticles under N2 ambient by reducing Cu(II) Acetate precursor with NaBH4.

The 9 meter long indigenously developed in-line magnetron sputtering system has been used to develop Cr/Au based synchrotron mirror, to be used in the soft X-ray wavelength range of 40-250A in the PASS beamline at INDUS-1 synchrotron source. Initially Cr/Au films of required thickness have been deposited on small c-Si and zerodour substrates and have been characterized by hard X-ray and soft X-ray reflectivity measurements. The deposition parameters of the sputtering system have been optimized and calibrated for depositing Cr and Au thin films of bulk like density, low surface roughness and ~1% thickness uniformity over a length of 1500 mm. The samples deposited under the optimized condition have been found to yield high soft X-ray reflectivity also in the desired wavelength range. Finally Cr/Au soft X-ray mirrors have been deposited under the above optimized conditions on plane (500 mm × 51 mm × 51 mm) and spheroidal (300 mm × 51 mm × 47 mm) zerodour substrates which will be installed in the PASS beamlin...

Thin film metallic glasses (TFMGs) exhibit properties superior to their bulk counterparts allowing them to be potentially useful in many practical applications. Apart from their technological interest, when converted to crystallized state (devitrification) TFMGs can also act as precursors for partially crystallized or fully crystallized forms. Such devitrified forms are attractive due to their novel structural and magnetic properties. The amorphous-to-crystalline transformation of co-sputtered Ni-Zr alloy thin films through annealing was studied using EXAFS (Extended X-ray Absorption Fine Structure) measurements. Investigation through an atomic probe gives a better insight into the local environment of the atomic species, rendering a deeper understanding of thermal evolution of such materials.

Co doped ZnO thin films have been prepared using rf magnetron sputtering technique with varying Co doping concentration. GIXRD has been used to probe long range order and Zn, Co and Oxygen K-edge XAFS measurements have been used for investigating local structure around Zn and Co atoms. GIXRD results show wurzite structure of the samples while XANES and EXAFS results at Zn and Co K edge show that Co is going at Zn site in ZnO matrix and no other phase is present. These results are further confirmed by O K edge and Co L2,3 edge XANES measurements.

Extended X-ray Absorption Fine Structure (EXAFS) measurements have been carried out on Mn doped CaF2 phosphors with synchrotron radiation at the Mn K edge. Measurements have been carried out on samples prepared with different concentrations of Mn dopants. The data have been analyzed to find out the Mn-F bond lengths and % of Mn doped CaF2 phase in the samples. The change in thermoluminescence glow peak temperature in CaF2:Mn phosphor with variation in Mn concentration has been correlated to the parameters obtained from EXAFS measurements.