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Effect of Mg doping on structural and magnetic properties of nano cobalt ferrites prepared via sol-gel auto-combustion method is reported. The sintered samples (Co 1-x Mg x Fe 2 O 4 , where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were characterized using X-ray diffraction, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer. Rietveld refinement of X-ray diffraction spectra shows the single phase cubic structure (space group Fd3m ) for the prepared samples. Raman spectroscopy reveals a doublet-like peak behavior in A 1g and E g modes arising due to different ionic radii of Co/Mg and Fe ions. Two prominent vibration frequencies in FTIR spectroscopy data also confirm the cubic spinel structure in the prepared samples. The magnetic parameters such as saturation magnetization, coercivity and remanence are studied with increasing the Mg-concentration in cobalt ferrite. Systematic changes in magnetic properties while going from x = 0 to 1 are discussed. [ABSTRACT FROM AUTHOR]

A unique applicability of Compton spectroscopy in probing the electronic states of rare earth aluminides using high energy (662 keV) γ-rays is reported. We have measured first-ever Compton profiles of Dy 1- x Er x Al 2 ( x =0, 0.2) using 20Ci 137 Cs Compton spectrometer. The charge reorganization in Dy 1 −x Er x Al 2 ( x =0, 0.2), on the formation of compound, has been discussed using the valence band Compton profile data. The experimental Compton profile data unambiguously establish charge transfer from Al to Dy (Dy and Er) on formation of x =0.0 (0.2) compound, which is in tune with spin polarized relativistic Korringa–Kohn–Rostoker (SPR-KKR) calculations. A reasonable agreement between SPR-KKR based Compton profiles and the experimental data show applicability of the Green function method in predicting the electronic properties of rare earth compounds. [ABSTRACT FROM AUTHOR]

Abstract: Isotropic Compton profile of NbB2 using 20 Ci 137Cs Compton spectrometer is compared with our theoretical profiles obtained from the density functional theory (DFT) within the first and the second order generalized gradient approximation (GGA) and the hybridization of Hartree–Fock and DFT. A good agreement between GGA based profiles and the experiment validates the applicability of second order GGA in momentum densities. Energy bands, density of states and real space analysis of the experimental profile show metallic character of NbB2. [Copyright &y& Elsevier]

Abstract: Isotropic Compton profiles of TaC and TaN have been measured for the first time, at an intermediate resolution, using 662keV γ-radiation. Energy bands, density of states and Fermi surface topology of TaC and TaN have been computed using linear combination of atomic orbitals with density functional theory and full potential linearised augmented plane wave method. Both band structure calculations predict the metallic character of TaC and TaN. The electron momentum densities calculated using various approaches of density functional theory are compared with the present measurements. On the basis of Mulliken’s population, it is also seen that TaC has more covalent bonding than TaN. The optical properties computed using full potential linearised augmented plane wave method are explained in terms of intraband transitions. [ABSTRACT FROM AUTHOR]

Abstract: Electronic structure of zinc-blende and wurtzite InN using linear combination of atomic orbitals and the latest approach of generalised gradient approximation within full potential linearised augmented plane wave schemes is reported. An unusual small band gap and real space analysis of our first ever experimental Compton profile are discussed. [Copyright &y& Elsevier]

Abstract: We report the first ever isotropic Compton profiles of mercury chalcogenides using our 740GBq 137Cs Compton spectrometer. To analyze our measurements, theoretical Compton profiles, energy bands, density of states and Mulliken''s populations are computed using pseudopotentials within the Hartree–Fock and density functional theories. A comparison of Compton data on equal-valence-electron-density scale shows the decrease of ionicity from HgS to HgTe. It is seen that these semiconductors have narrow band gap and exhibit inverted-type band structure. [Copyright &y& Elsevier]

Abstract: We present experimental Compton profiles of ZnSe along [100] and [110] directions using our 740GBq 137Cs Compton spectrometer. We have also computed the momentum densities, energy bands, density of states (DOS) and band gaps using density functional theory (local density and generalized gradient approximations) and pseudopotential (PP) approach. The anisotropy in the momentum density is well reproduced by the density functional calculations. The energy bands and bond length are interpreted in terms of the anisotropies. [Copyright &y& Elsevier]

Abstract: The Compton profile of holmium has been measured at an intermediate resolution (0.4a.u.) using 661.65keV gamma-rays. The measurement has been compared with our renormalized-free-atom (RFA) and free electron-based profiles. It is seen that the RFA model with e−–e− correlation is in relatively better agreement with the experiment. The data is interpreted in terms of hybridization of 4f band with the 5d–6s bands. From our RFA calculations, we have also computed the cohesive energy of the lanthanide. [Copyright &y& Elsevier]