Effect of Cu2+ and Ni2+ substitution at the Mn site in (La0.63Ca0.37)MnO3: A neutron powder diffraction investigation

Sulfite activation by Jahn-Teller-driven oxygen vacancies Cu-Mn composite oxide for chlortetracycline degradation

Copper-manganese composite metal oxides (CuMnOy) were prepared by hydrolysis-driven oxidation-reduction method and used to activate sulfite to degrade chlortetracycline hydrochloride (CTC) for the first time. The Jahn-Teller ions Mn3+ and Cu2+ exist in CuMnOy, which form a solid electric charge transport redox system and ensure the continuous generation of reactive oxygen species (ROS). Through the systematic study of the experimental parameters such as sulfite concentration, catalyst metal molar ratio, catalyst amounts and initial pH, the optimal degradation rate of CTC could reach 91.74% within 10 min and 94.46% after 30 min. The major reactive radicals were determined by radical quenching experiments and electron paramagnetic resonance (EPR) trapping techniques, and it was confirmed that SO4•- and •O2- played a nonnegligible role in the process of degrading CTC. Density functional theory (DFT) calculations show that higher Fukui indices (f- and f0) of CTC sites are more vulnerable to free radical attack. CuMnOy has low CTC degradation intermediate toxicity, high catalytic performance, good anti-interference ability, reusability and stability, and possesses decent application potential in the actual water treatment field.

Structural, microstructural and magnetic properties of (La(1-x)Ca(x))MnO3 nanoparticles

The crystal and magnetic structures of 10 and 20 nm sized (La1-xCax)MnO3 (x = 0.37, 0.50, 0.75) have been investigated between 5 and 300 K by means of Rietveld refinement of neutron powder diffraction data, coupled with transmission electron microscope observation and magnetization measurements. TEM observation reveals that nanoparticles are strongly affected by strain fields, probably originating from surface pressure. Irrespective of the composition, charge and orbital orderings are suppressed and Fz and Cy spin orderings coexist at low temperature; Cy and Fz orderings likely occur within the strained regions of the nanoparticles and in the matrix respectively. Moreover Gz and Az orderings are sometimes observed, and are likely to be taking place at the border of the strained regions.