Magnetic properties of Zn_0.7Co_2.3O₄₊δ spinel prepared by thermal decomposition of binary oxalates in air

Abstract

Magnetization and ac susceptibility of two Zn0.7Co2.3O4+δ spinel specimens obtained by decomposition of the binary oxalate Znx Co1–x C2O4·2H2O in air were measured in the temperature range 2–300 K. It is shown that the complex oxide Zn0.7Co2.3O4+δ formed right after the decomposition of the oxalate (at 220 °C) contains about 0.002 mass% metal cobalt, which is responsible for the dependence of the magnetic susceptibility χ on magnetic field at 300 K. Below 100 K, the χ = f (T) dependence of this specimen is characterized by divergence between curves measured under ZFC and FC conditions and a magnetic hysteresis loop at 2 K. The specimen synthesized at 700 °C does not contain a ferromagnetic component and is paramagnetic in the temperature interval 2–300 K. The observed differences in magnetic properties are explained by a higher degree of oxidation of cobalt and the nanodimensional state of the compound formed at a lower temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Novel cobalt zinc oxide Fischer–Tropsch catalysts synthesised using supercritical anti-solvent precipitation

“…This has previously been observed when Zn 2+ is incorporated into the Co 3 O 4 lattice. 17,37,38 The most significant shift occurs for the A 1g mode corresponding to oxygen vibrations in the CoO This journal is © The Royal Society of Chemistry 2014 diffusion through the lattice. 16 In this study, Zn x Co 3−x O 4 was formed in all samples at temperatures as low as 350 °C after just 2 h calcination.…”

“…This has previously been observed when Zn 2+ is incorporated into the Co 3 O 4 lattice. 17,37,38 The most significant shift occurs for the A 1g mode corresponding to oxygen vibrations in the CoO 6 octahedral unit in Co 3 O 4 . Recently Rubio-Marcos et al synthesised ZnCo 2 O 4 via a dry mixing method.…”

“…Cobalt zinc oxide has traditionally been used in dyes and pigments, 17,18 as gas sensors and adsorbents for Cl 2 , H 2 O and H 2 S, 19,20 semiconductors 21,22 and as a potential anode material in lithium ion batteries. 23 Recently there has been interest in its potential as a catalyst for alcohol oxidation, ethanol reforming and Fischer-Tropsch (FT) synthesis.…”