Raman and impedance spectroscopy methods of P sub(2)O sub(5)-Li sub(2)O-Al sub(2)O sub(3) glass system doped with MgO

Lithium diphosphate glasses doped MgO was prepared via a melt quenching technique. The samples were characterized by X-ray diffraction (XRD), Raman and impedance spectroscopy. XRD spectra reflected the amorphous nature of the glasses Raman spectra show structural network modifications with the composition variations of the studied glasses. Raman spectra of the studied glasses contain also typical phosphate glasses bands. Thus the band at ~698 cm super(-1) assigned to symmetric stretching vibrations of P-O-P groups and that from ~1168 cm super(-1) is attributed to symmetric stretching motions of the non-bridging oxygen (NBO) atoms bonded to phosphorous atoms (PO sub(2)) in phosphate tetrahedron. Electric properties were investigated using complex impedance spectroscopy in a frequency range from 40 Hz to 6 MHz at room temperature. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). Constant-phase elements (CPE) are used in equivalent electrical circuits for the fitting of experimental impedance data. The AC conductivity exhibited a Jonscher's universal power law according with the relation [sigma]( omega ) - [sigma](0) + A omega super(s) and it is observed that as the MgO content increases, frequency exponent (s) decreases.