Magnetic properties of CuFe1−xCrxO2 nanoparticles surrounded by amorphous SiO2

Abstract

CuFe1−xCrxO2 (0 ≤ x ≤ 1.0) nanoparticles surrounded by amorphous SiO2 with an average diameter of 30–50 nm were synthesized using a wet chemical method. The annealing temperatures were controlled to yield various sizes of single-phase CuFe1−xCrxO2 nanoparticles. CuFeO2 bulk crystal is known to have a multiferroic delafossite structure with two Néel temperatures of 11 and 14 K; however, the transition temperature shifted higher as the Cr–ion doping level increased. In addition, the lattice constants decreased in accordance with increased Cr-ion doping, which was confirmed by X-ray diffraction measurements. The magnetization curves showed weak ferromagnetic behavior and no coercivity was observed. Hence, frustration in the triangular lattice of the delafossite structure can be released by Cr–ion doping and higher magnetization can be expected. A fine structure analysis through X-ray absorption fine structure measurements was also conducted. It was found that the structure of the Cu ion is similar to that of Cu2O, and the c axis of the CuFe1−xCrxO2 should be shortened by the Cr–ion doping.

Delafossite Nanoparticle as New Functional Materials: Advances in Energy, Nanomedicine and Environmental Applications

“…The CuFeO 2 bulk crystal is known to be a multiferroic material with two Neel temperatures of 11 and 14 K [83][84][85][86][87][88][89][90]. However, doping with Cr caused the transition temperature shifted higher as the Cr-ion doping level increased [91]. They also observed weak ferromagnetic behaviour with no coercivity and changes in the lattice constants due to increased Cr-ion doping.…”

“…Doping can also change the magnetic or photo-properties of the pristine materials. The doping could cause changes of the magnetic properties [91], optical properties [99], andimproved their oxygen storage capacity (OSC) [100].…”

Regulation of Cr3+ doping on the defect characteristics and magnetic order in the CuFe1-xCrxO2 ceramics

“…reported that the electronic, thermoelectric and optical properties are significantly influenced by inducing spin entropy and lattice strain occurring due to the introduction of Cr 3+ ions. In the same year, Mori K [28]. proposed that the magnetic transition temperature increases and the magnetization enlarges as the Cr 3+ contents increase.…”