Local crystal structure and physical properties change of p -type transparent conducting oxide: CuCrO2 upon Ti-substitution

Abstract

A combination of high optical transparency and good electrical conductivity is realized in CuCrO2, a p-type transparent conducting oxide. With an aim to improve its physical properties, a CuCr1-xTixO2 (x = 0, 0.05, 0.1) series was prepared and investigated for its structural, electrical transport, and optical properties. Along with the lattice parameter values, refinement of X-ray diffraction profiles confirm the solubility limit of Ti within the delafossite unit cell. Electrical resistivity and heat capacity measured by varying the temperature further characterize the Ti-substituted compositions. As determined from ultraviolet-visible spectroscopy, no significant changes take place in the optical gap of CuCrO2 with Ti addition. Apart from confirming the 4+ valence state of Ti, the X-ray absorption near edge structure highlights the subtle changes taking place in the Cu-O hybridization upon Ti-substitution. The analysis of temperature dependent extended X-ray absorption fine structure spectroscopy, recorded at the Cr and Cu K-edge, emphasizes the impact of redistribution of charges on the local crystal structure. Cu-Cu hybridization along the a-axis appears to be influenced mainly by the temperature and only slightly by Ti substitution. © 2017 Author(s).