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In this paper, we demonstrate a combined theoretical and experimental study on the electronic structure, optical, and electrochemical properties of the β-Ag2MoO4 and Ag2O as significant Ag-containing compounds. These crystals...

In this work, the structural, energetic and electronic properties of Mg2FeH6 complex hydride have been studied using two different methods based on the density functional theory (DFT): the full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) and the pseudo-potentials plane waves (PP-PW) methods. Based on the calculated results, the ground state of Mg2FeH6 is found to be paramagnetic (PM), which is in agreement with experimental results, and also, the optimized structural parameters including lattice constants and atomic positions are very close to the experimental and other theoretical works. For a detailed study, electronic structure calculations including those of the energy band, density of states (DOS) and charge density distribution have been performed. It is found that Mg2FeH6 hydride is a semiconductor with a direct energy gap at the X-point of about 1.87 and 2.25 eV for the FP-LAPW + lo and PW-PP methods, respectively, and the Mg atom acts as a donor to form a cation ion and the negatively charged FeH6 complex results in a mainly ionic bonding between the Mg and FeH6 complex. Other physical and energetic properties such as bulk modulus, cohesive energy and formation enthalpy of Mg2FeH6 are in good agreement with the theoretically and experimentally determined values.

In this paper, strontium hexaferrite nanoparticles were synthesized by the sol-gel auto-combustion method. Effect of annealing temperature on crystal structure, morphology and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Also, the thermal decomposition of as-synthesized powdered samples has been studied by thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of single phase M -type hexagonal crystal structure for powders annealed above 950 • C, whereas the presence of hematite (α-Fe 2 O 3 ) as secondary phase was also observed for sample annealed at 900 • C. Furthermore, the crystallinity along with the crystallite size were augmented with annealing temperature. Comparison of the FT-IR spectra of the samples before and after annealing treatment showed the existence of metal-oxygen stretching modes after annealing. The thermogravimetric analysis confirmed the thermal decomposition of as-burnt powders happened in three-stage degradation process. The TEM images showed the nanoparticles like hexagonal-shaped platelets as the size of nanoparticles increases by increasing the annealing temperature. With increasing annealing temperature, the magnetic saturation and the coercivity were increased to the maximum value of 74.26 emu/g and 5.67 kOe for sample annealed at 1000 • C and then decreased. ‡ Corresponding author. 1550190-1 Int. J. Mod. Phys. B Downloaded from www.worldscientific.com by FLINDERS UNIVERSITY LIBRARY on 10/02/15. For personal use only. E. Roohani et al.

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