Tuning electrical properties of nanocrystalline Y2Zr2O7 pyrochlores by engineering the size of their particles

Influence of grain size on electrical properties of nanocrystalline yttrium zirconate (Y2Zr2O7) prepared by hydrothermal method is reported. Appropriate heat treatment has yielded different particle sizes in the range from 2.9 to 30.3 nm. Structural phase analysis by x-ray diffraction, Rietveld analysis and Raman spectroscopy confirmed the cubic pyrochlore structure of YZO. Electrical conductivity and dielectric properties of YZO as a function of temperature for different grain sizes have been studied by impedance spectroscopy. The smallest sized (2.9 nm) YZO exhibited a well-resolved grain and grain boundary conduction because of high fraction of grain boundary volume. Arrhenius type of electrical conduction was shown in YZO, and the conduction species was found to be oxygen vacancies. Activation energy was increasing from 1.14 to 1.32 eV with decreasing grain size. AC conductivity was obeying Jonscher's power law behaviour and non-overlapping small polaron tunnelling model was employed to explain the electrical conduction. Clear dependence of increasing conductivity with increasing grain size was established in YZO. Graphical abstract