Crystal structure, physical properties and bond valence analysis of NaLuP2O7

• Single crystals of NaLuP2O7 were prepared by flux method.
• The conductivity was analyzed in order to explain the mechanism of conduction.
• The most probable conduction pathways are determined.

Single crystals of a diphosphate NaLuP2O7 have been synthesized by the flux method and characterized by single-crystal X-Ray diffraction. NaLuP2O7 crystallizes in the monoclinic system with P21/n space group with cell parameters: a = 8.9985(8) Å, b = 5.3473(5) Å, c = 12.756(1) Å, β = 103.174° (1), V = 597.67 (9) Å3, Z = 4. Its structure consists of a three-dimensional framework of P2O7 units that are corner-shared by LuO6 octahedra, forming tunnels running parallel to [010] which are occupied by Na atoms. NaLuP2O7 powder was characterized by XRD, SEM, FTIR and Raman spectroscopy. The activation energy of (1.49 eV) obtained by electrical measurements suggests the charge carriers to be the sodium cations. The activation energies obtained from impedance and loss spectra were analyzed in order to explain the mechanism of conduction. The correlation between ionic conductivity of NaLuP2O7 and its crystallographic structure was investigated and the most probable transport pathway model was determined.

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