Preparation and properties of Sol–Gel derived CuFeO₂ thin films by dip-coating technique

Abstract

CuFeO 2 crystal thin films were successfully prepared by dip-coating technique through solgel route on silica glass substrates. Heat treatment under nitrogen atmosphere was necessary to obtain monovalent Cu and 800900°C firing was indispensable to prepare CuFeO 2 stable phase, and 29 h heat-treatment was appropriate to lower the electrical resistivity. For the dip-coated films, CuO impurity phase was observed in Cu:Fe = 1:1 solution from X-ray diffraction pattern (XRD), and thus the Cu containing solution of Cu:Fe = 0.99:1, 0.97:1, 0.95:1, 0.9:1and 0.8:1 were prepared to eliminate excess CuO phase. Too lower content of Cu such as 0.9:1 and 0.8:1 provided Fe oxides as impurity phase, but slight decrease of Cu iecreased the electric resistivity although CuO was still slightly observed by XRD. The visible transparency of the films was nearly 10%, and some films of conduction type was confirmed as p-type by measuring Hall effect.

Laser‐Annealing of Thermoelectric CuFe0.98Sn0.02O2 Films Produced by Powder Aerosol Deposition Method

“…On the one hand, the conductivity of the PAD surface layer after laser‐annealing is still reduced compared to the conductivity of bulk samples in literature (σ bulk = 0.06 to 0.09 S cm −1 ). [ 15 ] On the other hand, the conductivity of the surface layer is close to a CuFeO 2 PAD film that was annealed in a furnace at 900 °C (σ CuFeO2, ref = 0.03 S cm −1 ) and sol‐gel dip‐coated films after an annealing at 800 °C for at least 1 h. [ 15,48 ] When the microstructure of the surface layer is taken into account, the microcracks might lower the conductivity. As it was already shown in Figure 6, laser‐annealing is not completely homogeneous since the radiation power of the laser is not constant over the beam diameter and also the overlapping area of the laser beam has to be considered.…”

Revealing the impact of strontium doping on the optical, electronic and electrical properties of nanostructured 2H-CuFeO2 delafossite thin films

“…3R-CuFeO 2 thin films have been synthesized via several physical and chemical methods including pulsed laser deposition, 21 radiofrequency magnetron sputtering, 22 aerosol-assisted chemical vapor deposition, 23 electrodeposition, 24 spray pyrolysis, 25 and spin-coating. 26 In most previous attempts to prepare CuFeO 2 in thin-film form, complex and expensive routes were utilized, which poses a major drawback for practical applications. So far, only a few attempts have been made to grow a CuFeO 2 thin film corresponding to the hexagonal phase, especially through chemical deposition methods.…”