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M g 3 1 − x D y 3 x P O 4 2 (x=0, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06) are synthesized via solution combustion method using urea as fuel. The structure of undoped and Mg 3 (PO 4) 2 :Dy3+ (2 mol. %) phosphors are confirmed by XRD and found to be a monoclinic with space group P2 1 /n (14). The FTIR and Raman spectra confirms the presence of antisymmetric and symmetric stretching mode of (PO 4)3- group. X-ray photoelectron spectroscopy of Mg 3 (PO 4) 2 :Dy3+ (2 mol. %) phosphor confirms that the Dy ion present in 3+ ionic state. The PL emission spectra shows that the phosphor emits yellowish white light when excited with near UV light, i.e., 323, 348, 363, and 385 nm. The band gap of Dy3+ (2 mol. %) doped Mg 3 (PO 4) 2 is decreased as compared to the undoped phosphor due to the formation of intermediate levels between the energy band gap. [ABSTRACT FROM AUTHOR]

• Fe-doped TiO 2 amorphous thin films deposited using rf magnetron sputtering. • Band-gap energy reduction with Fe doping due to oxygen vacancy. • Maximum Fe substitution is up to 2 at. % doping. The present study deals with the local structure of amorphous TiO 2 and Fe-doped TiO 2 thin films deposited on Si substrate using magnetron sputtering. The absence of long range order is confirmed by grazing incidence x-ray diffraction and the short range order is studied using x-ray absorption near edge structure (XANES) measurements at Ti, Fe and O K-edges and Fe and Ti L 3 -edge. The XANES provides understanding about the electronic transition induced from the short range ordering and dependence of electronic hybridization of the central Ti- p orbitals with the Ti- d orbitals. The XANES measurements also show that maximum Fe doping concentration allowed to replace Ti is 2 at.% and after that separate phase starts appearing, which is consistent with simulation by ab-initio multiple scattering theory based code FEFF9. Ellipsometry measurements show gradual decrease in band-gap energy upto 2 at.% Fe doping from pristine TiO 2 , however a drastic decrease in band-gap energy is observed at 4 at.% or higher doping concentration due to formation of other phases. [ABSTRACT FROM AUTHOR]

Abstract: Zn 0.965 Cd 0.035 O/ZnO bilayer film has been developed using pulsed laser deposition (PLD) technique. The film is characterized by X-ray diffraction (XRD), energy dispersion analysis by X-ray (EDAX), UV-Vis and Valence band spectra (VBS). The XRD pattern confirms the single phase crystalline nature of the deposited film. The UV-Vis spectra establish a reduction of band gap (≈340meV) in the ternary alloy film of Zn 0.965 Cd 0.035 O/ZnO. The VBS shows shift in the peak corresponding to nonbonding oxygen p states. We also obtained valence band offset of 191meV in the film showing the rise of valence band. The calculated conduction band offset is found to be −51meV which confirms the lowering of the conduction band in the ternary alloy film. [Copyright &y& Elsevier]

In this work, Trivalent Sm (0.5−6 mol. %) doped mixed magnesium-zirconyl phosphor is synthesized by low temperature solution combustion method using urea as fuel. Phase formation, surface, and optical studies of the synthesized powder is characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), photoluminescence (PL) spectroscopy, and ultraviolet visible (UV–Vis) spectroscopy. XRD result reveals the formation of mixed MgO-ZrO 2 (cubic-tetragonal) phase. XPS technique is employed to examine the elemental composition of the synthesized material and results confirm the presence of Mg, Zr, O and Sm on the surface of the sample. The photoluminescence study shows that the synthesized phosphor gives four emission peaks at 567 nm, 602 nm, 651 nm, and 713 nm due to the electronic transitions of Sm3+ ion when excited under 403 nm. The photometric results reveal that the phosphor emits in the orange-red region of the color gamut and can be use as a warm light phosphor. The optical band gap of 4.74 eV is estimated from diffuse reflectance spectrum. [ABSTRACT FROM AUTHOR]

• Fabrication of Ca-doped BiFeO3 films using Pulsed Laser Deposition. • Improvement in the ferroelectric behavior of BiFeO3 films with Ca-doping. • Role of strong hybridization between Fe3d–O2p for the improvement in ferroelectric behavior. Effect of Ca – doping on electronic structure and ferroelectric properties have been studied on PLD grown Bi 1-x Ca x FeO 3 /SNTO (x = 0.05, 0.10, 0.20) films. The structural study confirms single crystalline (100) oriented epitaxial growth of the films. The observed improvement in the ferroelectric behavior with an increase in Ca – doping has been attributed to the strong hybridization between Fe3d–O2p and localization of Fe3de g and Bi6s-O2p orbitals understood using X-ray Absorption Spectroscopy measurements. Ferroelectric measurements performed on BCFO films show the finite value of intrinsic ferroelectric polarization, though the contributions from the non – ferroelectric components lead to unsaturated and leaky loop. The sub-bandgap transition observed in the absorption spectra indicates the presence of oxygen vacancy states which is one of the reasons for observed leakage in polarization measurements. [ABSTRACT FROM AUTHOR]

• Hex-Sr 0.6 Ba 0.4 MnO 3 shows short-range (SR) to long-range (LR) magnetic ordering. • Local structural changes in MnO 6 octahedra leads to SR to LR magnetic correlation. • Below the SR-LR crossover temperature, dipole-cluster glass state is observed. • Competitive-frustration among spin-exchange is responsible for dipole glass origin. • Negative magneto-dielectric coupling upto ~1.2% is observed. The crystal structure of hexagonal-Sr 0.6 Ba 0.4 MnO 3 allows various competing superexchange interactions, leading to intriguing magnetic properties. Local structural changes with temperature modify the overlapping between Mn and oxygen ions. Calculations based on our model spin-Hamiltonian reveal that the dominant antiferromagnetic superexchange interaction between the linearly oxygen-linked Mn4+ ions results in short range correlations (SRC), manifesting a smooth drop in magnetization below 325 K. Dominance of superexchange interaction changes its allegiance towards the non-linearly oxygen-linked Mn-O-Mn interactions, onsetting long-range correlations (LRC) below 225 K. Below the SRC-LRC crossover temperature, electrical response arising from the interacting dipoles exhibits power-law divergent behaviour of their relaxation time, upon cooling. Non-ergodic character of the dipole-cluster glass state is examined via the indispensable aging and rejuvenation effects, similar to the spin glasses. Competitive-frustration among spin-exchange and local-strain is reckoned as responsible for the electrical glass origin. [ABSTRACT FROM AUTHOR]