Increase in ionic conductivity in the nanocrystalline phase NaBi(MoO4)2:Gd3+

Abstract

Nanocomposite based on synthetic opal soaked with the NaBi(MO₄)₂:Gd³⁺ melt was characterized by X-ray diffraction patterns and Raman spectroscopy technique. Crystalline state of the substance inside opal pores was proved for the composite. The angular positions and intensities of reflections in X-ray diffractograms were different for nanocrystals compared to the crystal. Raman spectrum of opal – NaBi(MoO₄)₂ :Gd³⁺ was not essentially changed compared to that of the single crystal, except for a shift of some Raman bands. The total conductivity of nanocrystals was measured in the frequency range from 1 Hz to 1MHz and temperature range from 290 K to 473 K. Impedance hodographs (Nyquist plots) for nanocomposite were plotted. The energy of activation of conductivity and the nature of its frequency dependence were determined. Hopping conduction mechanism was established. The comparison of the temperature dependence with theory made it possible to estimate the average size of nanocrystals in opal pores.