Effects of iso- and polyvalent substitutions on the short/long-range crystalline order in CuCrO2 compounds

Compounds of pristine CuCrO2, doped CuCr0.96M0.03V0.01O2 (M = Ti, Mn, Ga and Nb), CuCr0.96V0.04O2, CuCr0.97Mg0.03O2, CuCr0.97Ni0.03O2and CuCr1-xFexO2 (x = 0.03, 0.06, and 0.09) were prepared by conventional solid-state route. Rietveld Refinement method using the Fullprof software confirms the single rhombohedral structure with space group R-3m for all the studied samples. It was found that doped ion having a larger ionic radius shows an increase in the unit cell volume for CuCrO2, while the unit cell volume decreases or remains nearly unchanged for dopant having a slightly smaller ionic radius. Negligible strain is observed in the pristine, Mn, Ga and Nb doped samples, whereas other dopants show strained growth. It was found that samples with Ti and Fe doping exhibit the maximum strain. Although, no significant changes in the frequencies of Raman active modes A1g and Eg were detected, strong local distortions were observed in the Mn, Ti and Fe doped samples. In addition, the CuCrO2 compounds doped with V, Ga, Nb, Ti and Mn ions exhibit splitting of IR active Eu and A2u modes. •Mg2+ & Nb doping up to 3 atomic % in CuCrO2 samples was achieved for the first time.•Strong local distortions for the Mn, Ti and Fe doped samples were observed in Raman.•Lo-To splitting in A2u and Eu modes was observed in FTIR measurements.•Such comparison of FTIR and Raman spectroscopy is presented for the first time.•Bond distances and/or bond angles are mainly affected by electron or hole doping.