STRUCTURAL AND MAGNETIC PROPERTIES OF GLASSY PHOSPHATES WITH NASICON-LIKE FRAMEWORK

摘要

The structural and magnetic properties of vitreous materials containing transition metal cations - Li_xM_2(PO_4)_x (M = Fe, V, Mo and x = 3, 5, 6, respectively) which crystallize with the Nasicon-like structure have been studied. Information concerning local cationic environments and configuration of (PO_4)~(3-) polyanions and P-O-P bridges have been concluded from Raman and Fourier Transform Infrared (FTTR) spectroscopy investigations. The vibrational spectrum of Li_xM_2(PO_4)_x is dominated by two very strong and broad bands located in mid-infrared and in the far-infrared range. A third band is attributed to the P-O-P ring of P_2O_5 glass former. Studies of the magnetic susceptibility have been carried out by Superconducting Quantum Interference Device (SQUID) measurements. Temperature dependence of magnetic susceptibility of the samples with Fe- and V- containing compounds follows a Curie-Weiss model at room-temperature and below down to Neel point. For the Mo-based compounds, a different behavior has been observed; this material behaves as diamagnetic in the whole range of temperature.