Luminescence and Structural Properties on Sm3+ Doped KBR Single Crystals

Abstract

KBr (pure as well as doped with suitable impurities) is probably the most extensively studied of the alkali halides [1][2][3] . Recent years more efforts have been made for the development of rare earth ions activated luminescent materials for their wide range of potential application in optoelectronic devices, temperature sensors, so lid state lighting, optical communication system and luminescent probes [4][5][6][7][8][9] . Samarium is an active ion for different inorganic host lattice and act as a powerful emitting centre due to its energy level structure and high luminescence efficiency [10] . The large ionic radius of potassium ions permits incorporation of a large number of cationic impurities. The sites of dopants determined by their ionic radii. The radii of Sm 3+ are 0.958. Most of the work has been done in samarium doped materials as powder and glasses [11][12][13] . In the present work Sm 3+ doped KBr crystals has been grown by Bridgeman Stockbarger technique and the grown crystals were characterized by Fourier Transform Infrared (FTIR), X-Ray Diffraction method(XRD), Scanning Electron Microscopy(SEM), Electron Paramagnetic Resonance(EPR). ExperimentalSingle crystals of Samarium doped KBr (99.99% purity) were grown using Bridgemann Stockbarger technique. Samarium was added in the form of Samarium fluoride (Aldrich 99.99% purity). The crystal grown with three different impurity concentrations 1%, 3% and 5% by weight. The results due to three concentrations were similar except high luminescence yield for crystals with a high concentration. Hence only the results pertaining to Samarium concentration of 5% by weight are presented and discussed. All the measurements were performed at room temperature. Laser Raman Scattering Spectrum were taken using Reinsaaw Invia spectrometer with red laser. X-ray diffraction spectrum of the prepared sample by using (Rigaku) X-ray diffractometer (CuK α , λ=1.5443Å) at the rate of 2°/min and the variation of 2θ is from 10° to 90°. The morphologies of the samples were inspected using Scanning Electron Microscopy SEM-JEOL-JSM 5610LV model. EPR spectrum were recorded using a EPR spectrometer at microwave frequency (9-10 GHz) at room temperature with a magnetic field modulation of 100 KHz to obtained first derivative EPR signal. Laser Raman ScatteringWe have used red laser as the excitation wavelength to record Raman spectrum. The Raman spectrum obtained at room temperature using the excitation wavelength λ L = 785nm is shown in Fig.1. It composed of three main peaks at 107Cm -