Oxygen defect engineering by the current effect assisted with temperature cycling in a perovskite-type La_0.7Sr_0.3CoO₃ film

Abstract

Introducing and modulating the oxygen deficiency concentration have been received as an effective way to obtain high catalytic activity in perovskite oxides. However, it is difficult to control the oxygen vacancy in conventional oxygen defect engineering due to harsh reaction conditions at elevated temperatures and the reducing atmosphere, which make it impractical for many technological applications. Herein, we report a new approach to oxygen defect engineering based on the combination of the current effect and temperature cycling at low temperature. Our investigations revealed that the electrical conductivity of the (011)-LaSrCoO/PMN-PT film changes continuously from metallicity to insulativity under repeated transport measurements below room temperature, which indicates the transformation of the Co state to Co in the film. Further experiments and analysis revealed that oxygen vacancies can be well regulated by the combined current effect and temperature cycling in repeated measurements, which results in a decrease of Co/Co and thus the remarkable variation of conductive properties of the film. Our work provides a simple and highly efficient method to engineer oxygen vacancies in perovskite-type oxides and brings new opportunities in designing high-efficiency oxidation catalysts.

Enhanced Stability and Thickness‐Independent Oxygen Evolution Electrocatalysis of Heterostructured Anodes with Buried Epitaxial Bilayers

“…The photoemission and EIS measurements taken together indicate a conversion of Co 4+ to Co 3+ during contact formation for the ultrathin LSCO films grown on NSTO due to the electron transfer from the n‐type substrate, resulting in hole depletion and a higher resistivity of the LSCO films. Our observations are consistent with the ones about a combined effect of current and temperature cycling in repeated measurements of L 0.7 Sr 0.3 CoO 3 thin films, which has been shown to decrease the Co 4+ /Co 3+ ratio and was related to an increase in the resistance of LSCO films …”

Cationic Defect Engineering for Controlling the Infrared Absorption of Hexagonal Cesium Tungsten Bronze Nanoparticles

“…Controllably introduced defects alter the density of localized charges, which affect the charge mobility and the response to an incident electromagnetic field and other chemicals . Based on this principle, structural defects have been engineered to control the electronic, , optical, ionic transport, adsorption, and catalytic properties of metal oxides.…”

Tuning magnetic anisotropy by interfacial engineering in La2/3Sr1/3Co1 – xMnxO2.5 + δ/La2/3Sr1/3MnO3/La2/3Sr1/3Co1 – xMnxO2.5 + δtrilayers*

“…The calculation gives ∼ 3.385 × 10 6 erg/cm 3 of the K A for LSCO/LSMO/LSCO trilayer at 10 K, which is more than one order of magnitude larger than that of bare LSMO film with magnetoelastic coupling interaction (∼ 10 4 erg/cm 3 ). [16,[25][26][27] Here, the positive value of K A stands for the PMA of trilayers. Following the same procedure, the M-H curve of LSCMO/LSMO/LSCMO (x = 0.7) trilayer at 10 K is obtained as shown in Fig.…”

“…Different from LSMO, the tensile-strained La 2/3 Sr 1/3 CoO 3 thin films easily lose oxygen to form ordering of oxygen vacancies, i.e., the brownmillerite structure of La 2/3 Sr 1/3 CoO 2.5+δ (LSCO). [25,26] The P/BM interface based heterostructures can be formed by grouping the LSCO and LSMO film together, and such symmetry mismatch at the interface may possibly tune the MA of the LSMO layer. Moreover, using Mn ions to substitute Co ions can effectively modulate the lattice structure of La 2/3 Sr 1/3 Co 1−x Mn x O 2.5+δ (LSCMO) film from brownmillerite to perovskite.…”