Room-temperature selective epitaxial growth of CoO (1 1 1) and Co3O4 (1 1 1) thin films with atomic steps by pulsed laser deposition

A holistic analysis of surface, chemical bonding states and mechanical properties of sol-gel synthesized CoZn-oxide coatings complemented by finite element modeling

“…Over the years, efforts have been made to investigate Co 3 O 4 structures due to their fascinating structural, electrical, chemical, electronic, mechanical, optical, photo-chemical, and magnetic properties [17,18]. Co 3 O 4 , a direct band-gap semiconducting oxide has been extensively used as catalysts, Li-ion batteries, gas sensors, supercapacitors, energy storage and energy conversion devices, thin film materials, solar selective surfaces, drug deliveries, and magneto-optic recording media [19,20].…”

Property and cation valence engineering in entropy-stabilized oxide thin films

“…S6 and S7 [30]). The entropy-stabilized nature of J14 appears to disperse the Co 3+ enough to prevent the nucleation of Co 3 O 4 or other higher oxide phases, which commonly occurs in binary transition metal rocksalt oxide films to accommodate cation oxidation to 3+ [50][51][52]. Judging from our structural models, 400 °C likely represents a threshold tem- perature, below which Co 3+ is incorporated into the rocksalt structure and above which metastable Co 3+ converts to a more stable 2+ state at the growing surface to produce a phase similar to bulk J14.…”

“…Dispersions for 400-600 °C films are similar, but as substrate temperature decreases below 400 °C, features in k (related to absorption coefficient α = 4π k λ , and wavelength λ), shift to longer wavelengths and increase in magnitude. Considering the optical response of native Co oxides in the context of their net Co valence, Co 3 O 4 possesses a smaller band gap and additional low-energy optical transition compared to CoO [50]. Similarly, J14 films with enhanced Co 3+ concentrations possess a smaller band gap and more pronounced absorption features.…”

Synthesis of Co 3 O 4 –ZnO mixed metal oxide nanoparticles by homogeneous precipitation method

“…The optical band gap (E g ) of Co 3 O 4 -ZnO mixed metal oxide nanoparticles is determined by extrapolation of the linear relationship between (αhυ) 2 and (hυ) [8] :…”