Structural analysis and temperature dependent conductivity of La_xCu_1-xO shrimp-like nanostructures synthesised via wet chemical precipitation

A series of well textured undoped and La-doped CuO (La_xCu_1-xO, x = 0, 0.03, 0.06 and 0.10) nanostructures were synthesised via a low cost and facile wet chemical precipitation route. The structural, optical and temperature dependent electrical properties of the products were investigated and correlated. X-ray diffraction (XRD) showed formation of a pure phase of monoclinic CuO (undoped and 3–6 at.% La-dopped sample) and CuO-La₂O₂CO₃ mixed phase in the higher doped sample (10 at.%). Scanning electron microscopy revealed shrimp like nanostructures of diverse sizes and aspect ratios for all the samples. The samples showed an optical absorption spectra with cut-off wavelengths lying in the visible spectral region. The temperature dependent electrical conductivity was measured and the trends depicted a typical semiconducting behaviour in all the samples. La doping of >3 at.% was associated with increased resistivity and premature levelling of the conductivity profiles at higher temperature. At 523 K, the electric field generated mobility and carrier concentration product values were observed to drop monotonously with doping. At room temperature the values were found to increase from 7.11 × 10¹⁴ (cm.s.V)⁻¹ for the 0 at.% to peak at 2.16 × 10¹⁵ (cm.s.V)⁻¹ for the 3 at.% and dropped to 8.95 × 10¹³ at 10 at.%. The conduction mechanism was explained on the basis of the hopping model.