Electronic depiction of magnetic origin in undoped and Fe doped TiO2-d epitaxial thin films

We have investigated the electronic and magnetic properties of the pulsed laser deposited epitaxial thin films of undoped and Fe doped (4 at. %) anatase TiO2-d by photoemission, magnetization measurements, and ab-initio band structure calculations. These films show room temperature magnetic ordering. It is observed that Fe ions hybridize with the oxygen vacancy induced Ti3+ defect states. Our study reveals the formation of local magnetic moment at Ti and Fe sites to be responsible for magnetic ordering. A finite density of states at the Fermi level in both undoped and Fe doped films is also observed, suggesting their degenerate semiconducting nature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3640212]991

Aqueous Solution Preparation, Structure, and Magnetic Properties of Nano-Granular ZnxFe3−xO4 Ferrite Films

This paper reports a simple and novel process for preparing nano-granular ZnxFe3−xO4 ferrite films (0 ≤ x ≤ 0.99) on Ag-coated glass substrates in DMAB-Fe(NO3)3-Zn(NO3)2 solutions. The deposition process may be applied in preparing other cations-doped spinel ferrite films. The Zn content x in the ZnxFe3−xO4 films depends linearly on the Zn2+ ion concentration ranging from 0.0 to 1.0 mM in the aqueous solutions. With x increasing from 0 to 0.99, the lattice constant increases from 0.8399 to 0.8464 nm; and the microstructure of the films changes from the non-uniform nano-granules to the fine and uniform nano-granules of 50–60 nm in size. The saturation magnetization of the films first increases from 75 emu/g to the maximum 108 emu/g with x increasing from 0 to 0.33 and then decreases monotonously to 5 emu/g with x increasing from 0.33 to 0.99. Meanwhile, the coercive force decreases monotonously from 116 to 13 Oe

Zinc oxide nano particle grown by soft solution route at room temperature

Zinc oxide thin films were deposited by simple soft solution route at room temperature. The as grown thin films of ZnO were characterized for the structural, morphological and optical properties. X-ray diffraction (XRD) analysis reveals the polycrystalline nature of ZnO thin films with hexagonal structure. The films were highly oriented along (100) and (101) planes. The broad and low intense peaks in XRD pattern indicate the presence of coarsely fine, nano crystalline grains. Transmission Electron Microscopy (TEM) micrographs shows the formation of ZnO nanocrystallites. Atomic Force Microscopy (AFM) image shows uniform deposition of ZnO thin film on the substrate. The optical band gap was found to be 3.37 eV for as grown films. © 2009 American Institute of Physic

Effect of Fe doping on the magnetic ordering temperature of ErMnO3

We studied the effect of Fe doping on structural, magnetic, and dielectric properties of hexagonal ErMnO3 system. For 50% doping of Fe on Mn site in ErMnO3 modulated its crystallographic structure from hexagonal to orthorhombic phase. Accompanied with the structural phase transition in ErMnO3, the magnetic properties are effectively modified. The Fe doped samples exhibit enhancement in antiferromagnetic ordering Neel temperature (T-N) from 77K (ErMnO3) to 280K (ErFe0.5Mn0.5O3). The anomalies observed in the dielectric constant around T-N in doped ErMnO3 samples indicate the coupling between electric and magnetic order parameters. (C) 2015 AIP Publishing LLC

A comparative study of the physical properties of CdS, Bi<inf>2</inf>S<inf>3</inf> and composite CdS-Bi<inf>2</inf>S<inf>3</inf> thin films for photosensor application

Thin films of CdS, Bi2S3 and composite CdS-Bi2S3 have been deposited using modified chemical bath deposition (M-CBD) technique. The various preparative parameters were optimized to obtain good quality thin films. The as-deposited films of CdS, Bi2S3 and composite were annealed in Ar gas at 573 K for 1 h. A comparative study was made for as-deposited and annealed CdS, Bi2S3 and composite thin films. Annealing showed no change in crystal structure of these as-deposited films. However, an enhancement in grain size was observed by AFM studies. In addition change in band gap with annealing was seen. A study of spectral response, photosensitivity showed that the films can be used as a photosensor. © 2007 Elsevier B.V. All rights reserved

Effect of annealing on structural and optical properties of zinc oxide thin film deposited by successive ionic layer adsorption and reaction technique

Zinc oxide thin films are grown by successive ionic layer adsorption and reaction technique at room temperature. The as-grown films were annealed at different temperatures, viz. 350, 400, 450, and 500 °C in air atmosphere for 2 h. Effect of annealing on the physical properties of ZnO thin films has been studied. XRD analysis reveals the polycrystalline nature for ZnO thin films with hexagonal phase. The films were highly oriented along (1 0 0) and (1 0 1) planes, an enhancement in these peaks is the significance of the post-deposition annealing treatment on ZnO thin films. The optical studies of the samples show that the energy band gap was decreased in accordance with the annealing temperature. The results of optical studies were strengthened by photoluminescence (PL) studies. © 2008 Elsevier B.V. All rights reserved

Photoelectron spectroscopy beamline on Indus-1 synchrotron radiation source

We describe here a photoelectron spectroscopy beamline installed on Indus-1 storage ring. Initially we give a brief description of optical and mechanical layout of beam-line. The beamline optics was designed to cover energy range from 10 eV to 200 eV and it consists of a pre-focusing mirror, a toroidal grating monochromator and a post-focusing mirror. We then discuss indigenously developed ultra high vacuum compatible work station to carry out angle integrated photoemission experiments. The beamline has been successfully commissioned and photoemission measurements on a variety of standard samples are presented

Improved photocatalytic activity of TiO₂ nanoparticles through nitrogen and phosphorus co-doped carbon quantum dots: An experimental and theoretical study

In this work, we develop a photocatalyst wherein nitrogen and phosphorus co-doped carbon quantum dots are scaffolded onto TiO2 nanoparticles (NPCQD/TiO2), denoted as NPCT hereafter. The developed NPCT photocatalyst exhibits an enhanced visible light photocatalytic hydrogen production of 533 μmol h−1 g−1 compared to nitrogen doped CQD/TiO2 (478 μmol h−1 g−1), phosphorus doped CQD/TiO2 (451 μmol h−1 g−1) and pure CQD/TiO2 (427 μmol h−1 g−1) photocatalysts. The enhanced photocatalytic activity of the NPCT photocatalyst is attributed to the excellent synergy between NPCQDs and TiO2 nanoparticles, which results in the creation of virtual energy levels, a decrease in work function and suppressed recombination rates, thereby increasing the lifetime of photogenerated electrons. A detailed mechanism is proposed for the enhancement in visible light hydrogen production by the NPCT photocatalyst from the experimental results, Mott–Schottky plots and ultraviolet photoelectron spectroscopy results. Further, first-principles density functional theory (DFT) simulations are carried out which predict the decrease in the work function and band gap, and the increase in the density of states of NPCT as the factors responsible for the observed enhancement in visible light photocatalytic hydrogen production

Modifications of structural, optical and electrical properties of nanocrystalline bismuth sulphide by using swift heavy ions

Modified chemical bath deposited (MCBD) bismuth sulphide (Bi2S3) thin films' structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 °C and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 1012 ions/cm2 fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model. © 2008 Elsevier B.V. All rights reserved