Nanomaterials, Vol. 15, Pages 1093: Cu-Doping Induced Structural Transformation and Magnetocaloric Enhancement in CoCr2O4 Nanoparticles

Nanomaterials doi: 10.3390/nano15141093

Authors:
Ming-Kang Ho
Yun-Tai Yu
Hsin-Hao Chiu
K. Manjunatha
Shih-Lung Yu
Bing-Li Lyu
Tsu-En Hsu
Heng-Chih Kuo
Shuan-Wei Yu
Wen-Chi Tu
Chiung-Yu Chang
Chia-Liang Cheng
H. Nagabhushana
Tsung-Te Lin
Yi-Ru Hsu
Meng-Chu Chen
Yue-Lin Huang
Sheng Yun Wu

This study systematically investigates the impact of Cu2+ doping on the structural, magnetic, and magnetocaloric properties of CuxCo1−xCr2O4 nanoparticles synthesized via a solution combustion method. Cu incorporation up to x = 20% induces a progressive structural transformation from a cubic spinel to a trigonal corundum phase, as confirmed by X-ray diffraction and Raman spectroscopy. The doping process also leads to increased particle size, improved crystallinity, and reduced agglomeration. Magnetic measurements reveal a transition from hard to soft ferrimagnetic behavior with increasing Cu content, accompanied by a notable rise in the Curie temperature from 97.7 K (x = 0) to 140.2 K (x = 20%). The magnetocaloric effect (MCE) is significantly enhanced at higher doping levels, with the 20% Cu-doped sample exhibiting a maximum magnetic entropy change (−ΔSM) of 2.015 J/kg-K and a relative cooling power (RCP) of 58.87 J/kg under a 60 kOe field. Arrott plot analysis confirms that the magnetic phase transitions remain second-order in nature across all compositions. These results demonstrate that Cu doping is an effective strategy for tuning the magnetostructural response of CoCr2O4 nanoparticles, making them promising candidates for low-temperature magnetic refrigeration applications.

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