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A new rare-earth-free NaZnPO4:Mn2+ (NZP:Mn) phosphor powder has been developed by our group and investigated meticulously for the first time using secondary ion mass spectroscopy and chemical imaging techniques. The studies confirmed the effective incorporation of Mn2+ into the host lattice, resulting in an enhancement of photoluminescence intensity. Phase purity has been verified and structure parameters have been determined successfully by Rietveld refinement studies. The NZP:Mn phosphor powder exhibits strong absorption bands in the ultraviolet and visible (300-470 nm) regions with a significant broad yellow-green (~543 nm) emission due to the characteristic spin forbidden d-d transition (4T1→6A1) of Mn2+ ions, indicating weak crystal field strength at the zinc-replaced manganese site. The decay constants are a few milliseconds, which is a pre-requisite for applications in many display devices. The results obtained suggest that this new phosphor powder will find many interesting applications in semiconductor physics, as cost-effective light-emitting diodes (LEDs), as solar cells and in photo-physics. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We demonstrate the distinct glassy transport phenomena associated with the phase separated and spin-glass-like phases of La0.85Sr0.15CoO3, prepared under different heat-treatment conditions. The low-temperature annealed (phase-separated) sample, exhibits a small change in resistance, with evolution of time, as compared to the high-temperature annealed (spin glass) one. However, the resistance change as a function of time, in both cases, is well described by a stretched exponential fit, signifying the slow dynamics. Moreover, the ultraviolet spectroscopy study evidences a relatively higher density of states in the vicinity of EF for low-temperature annealed sample and this correctly points to its less semiconducting behavior. [ABSTRACT FROM AUTHOR]

We have studied the temperature-dependent changes in the near EF electronic structure of the electron-doped, phase separated colossal magnetoresistance (CMR) compound, Cao.86Pro.14MnO3 using photoemission and x-ray absorption studies. At low temperatures, this compound shows a high eg electron density near the EF though the compound is insulating. Photoemission measurements further showed a temperature dependence of the eg electron occupation and localization while the complementary results of XAS showed corresponding changes in the number of unoccupied states. Our results indicate a transfer of charges from the t2g states to the eg band, probably due to a decrease in the crystal field splitting in the ferromagnetic metallic (FMM) phase following the structural changes of the Mn06 octahedra at low temperatures. We have interpreted our results from a FMM-antiferromagnetic insulating (AFMI) phase separation scenario. [ABSTRACT FROM AUTHOR]

We have studied the concentration-dependent near-Fermi-level valence-band electronic structure of Sm0.1Ca0.9-xSrxMnO3 (x=0, 0.1, 0.3, and 0.6) using high-resolution ultraviolet photoelectron spectroscopy (HRUPS) across the metal insulator transition. At low temperatures (50 and 100 K), a transformation from pseudogap type behavior (x=0 and 0.1) to insulating behavior (x=0.3 and 0.6) is observed with an increase in Sr content. While at the high temperatures, the metalliclike density of states appears up to x=0.3 and then vanishes at x=0.6. The temperature-dependent spectra reveal a changeover from pseudogap to metalliclike states for x=0 above its magnetic cluster-glass ordering temperature (110 K). In the case of x=0.1, the temperature-dependent change in the density of states is quite different from that of x=0 due to the weaker cluster-glass component and exhibits an interesting spectral weight transfer in the high-temperature paramagnetic phase. These findings would immensely help in understanding the puzzling charge transport scenario in Sm0.1Ca0.9-xSrxMnO3 from a microscopic point of view. [ABSTRACT FROM AUTHOR]

We demonstrate the distinct glassy transport phenomena associated with the phase separated and spin-glass-like phases of La0.85Sr0.15CoO3, prepared under different heat-treatment conditions. The low-temperature annealed (phase-separated) sample, exhibits a small change in resistance, with evolution of time, as compared to the high-temperature annealed (spin glass) one. However, the resistance change as a function of time, in both cases, is well described by a stretched exponential fit, signifying the slow dynamics. Moreover, the ultraviolet spectroscopy study evidences a relatively higher density of states in the vicinity of EF for low-temperature annealed sample and this correctly points to its less semiconducting behavior. [ABSTRACT FROM AUTHOR]

The present study highlights the potential application of zinc peroxide (ZnO 2 ) nanomaterial as an efficient material for the decontamination of cyanide from contaminated water. A process patent for ZnO 2 synthesis has been granted in United States of America (US Patent number 8,715,612; May 2014), South Africa, Bangladesh, and India. The ZnO 2 nanomaterial was capped with polyvinylpyrrolidone (PVP) to control the particle size. The PVP capped ZnO 2 nanomaterial (PVP-ZnO 2 ) before and after adsorption of cyanide was characterized by scanning electron microscope, transmission electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy and time of flight-secondary ion mass spectrometry. The remaining concentration of cyanide after adsorption by PVP-ZnO 2 was determined using ion chromatograph. The adsorption of cyanide over PVP-ZnO 2 was also studied as a function of pH, adsorbent dose, time and concentration of cyanide. The maximum removal of cyanide was observed in pH range 5.8-7.8 within 15min. The adsorption data was fitted to Langmuir and Fruendlich isotherm and it has been observed that data follows both the isotherms and also follows second order kinetics., (Copyright © 2016. Published by Elsevier B.V.)

A new rare-earth-free NaZnPO4:Mn(2+) (NZP:Mn) phosphor powder has been developed by our group and investigated meticulously for the first time using secondary ion mass spectroscopy and chemical imaging techniques. The studies confirmed the effective incorporation of Mn(2+) into the host lattice, resulting in an enhancement of photoluminescence intensity. Phase purity has been verified and structure parameters have been determined successfully by Rietveld refinement studies. The NZP:Mn phosphor powder exhibits strong absorption bands in the ultraviolet and visible (300-470 nm) regions with a significant broad yellow-green (~543 nm) emission due to the characteristic spin forbidden d-d transition ((4)T1→(6)A1) of Mn(2+) ions, indicating weak crystal field strength at the zinc-replaced manganese site. The decay constants are a few milliseconds, which is a pre-requisite for applications in many display devices. The results obtained suggest that this new phosphor powder will find many interesting applications in semiconductor physics, as cost-effective light-emitting diodes (LEDs), as solar cells and in photo-physics., (Copyright © 2015 John Wiley & Sons, Ltd.)