Md. Jamal

Electron spin resonance and optical absorption spectra of Cu2+ ions in xNaI(30 - x)Na2O70B2O3 glasses

Electron spin resonance (ESR) and optical absorption spectra of xNaI(30 - x)Na2O70B2O3 glasses containing 1 mol% CuO have been investigated at room temperature. The optical absorption spectra of all the glass samples exhibited a broad asymmetric absorption band which correspond to the d—d transitions bands due to Cu2+ ions. From the ESR spectra the spin-Hamiltonian parameters were evaluated. It was observed that the ground state of Cu2+ is dx2 - y2 orbital and the site symmetry around Cu2+ ions is tetragonally distorted octahedral. The bonding co-efficients were evaluated using the optical and ESR data to obtain information about Cu2+-ligand bond nature. The basicity of σ-type symmetry was independent of the glass composition while the π-type basicity was found to vary as a function of the glass composition.

Electron paramagnetic resonance study of vanadyl ions in Nal-Na2O-B2O3 glasses

Electron paramagnetic resonance (EPR) studies of glasses doped with transition metal ions have been used to obtain information about the glassy network and to identify site symmetry around the transition metal ion [1]. There has been considerable interest in the physical properties of alkali halo borate glasses because of their fast ionic conductivity [2-4]. In this letter we report the EPR studies of the transition metal ion VO 2+ in the alkali halo borate glass system xNaI-yNa20-70B203. The starting materials used were analar grade reagents of boric acid (H3BO3), sodium carbonate (NazCO3) and sodium iodide (NaI). The amounts were calculated to form 10 g of each glass. Each batch was first sintered at about 723 K then melted in a porcelain crucible in an electrically heated furnace at a temperature of 1173 K. The melts were quenched at 473 K in air by pouring them onto a stainless steel plate which was maintained at 473 K. The glasses were annealed for 24 h at the same temperature to relieve the mechanical stress. To each batch 1 mol % of 702+ was added in the form of 7205 as paramagnetic probe. Table I gives the glass composition in mol %. X-ray power patterns revealed the TABLE I Composition of the glasses Composition (%)

Solid state battery with pure and doped sodium yttrium fluoride as the solid electrolyte

Solid state batteries using pure and doped sodium yttrium fluoride as the solid electrolytes were fabricated at ambient temperature. The discharge characteristics of the cells for a load of 1 M Omega were studied. The cell with NaYF4:Dy as the solid electrolyte exhibited a larger plateau region compared with the other cells. Open circuit voltage and short circuit current of the cells range from 2.5 to 2.7 V and 7 mu A to 435 mu A respectively. The performances of the cells under varying loads for a constant voltage of 1.5 V were also investigated. Various cell parameters were evaluated.

Ionic transport and battery characterization studies of barium-doped potassium yttrium fluoride

Abstract Pure and barium fluoride doped potassium yttrium fluoride materials were synthesized using the solid state reaction method and were characterized by X-ray diffraction, transference number and transient ionic current measurements. In all the samples the conductivity was found to be mainly ionic while the electronic conductivity was found to be small. Solid state batteries were fabricated in the configuration K/electrolyte/(I2 + C + electrolyte) with KYF4 and KYF4: BaF2 as the solid electrolytes. Their discharge characteristics were studied for a load of 100 K Ω at 313 K. Open circuit voltage (OCV) and short circuit current (SCC) of the cells range from 2.38 to 2.82 V and 650 to 2340 μA, respectively. Various cell parameters were evaluated.

Ionic transport and battery characterization studies on 15NaF-15Na2O-70 [(1 − x)B2O3 − xCr2O3] quaternary glassy systems

Abstract Glasses in the quaternary system 15NaF-15Na 2 O-70-[(1 − x ) B 2 O 3 - xCr 2 O 3 ] have been prepared by a melt quenching method and characterized by X-ray diffraction, differential scanning calorimetry (DSC) and electrical conductivity. The conductivity was found to vary in a non-linear manner with the composition x . The highest conductivity composition glass was used as an electrolyte in the fabrication of a solid state cell. Its discharge characteristics were investigated at ambient temperature. The open circuit voltage of the cell was found to be 2.6 V while the short circuit current was 1000 μA. Various cell parameters were evaluated.

Ionic transport and battery characterization studies on NaINa2OB2O3 ternary glassy system

Abstract Glasses in the ternary system xNaI-yNa2O-[100−(x+y)]B2O3 prepared by a melt quenching method are characterized by using different experimental techniques such as X-ray diffraction, ionic transference number and conductivity. The conductivity is found to vary in a non-linear manner with change in the NaI/Na2O ratio. The highest conductivity glass composition is used as an electrolyte in the fabrication of a solid-state electrochemical cell. A decomposition potential of 2.5 V is determined for the electrolyte. The discharge chracteristics of the cell are investigated at ambient temperature and various cell parameters are determined. The open-circuit voltage and short-circuit current of the cell are 2.7 V and 1600 μA, respectively.