Magnetism of Cr and Cu Doped High-Entropy Oxides AITranslate
Abstract AITranslate
Aiming at the limitations in magnetic regulation of high-entropy oxides （HEOs），this study systematically investigated the influence mechanisms of crystal structures （perovskite and spinel） and elemental doping （Cr，Cu，Sb） on HEOs' magnetic properties. Perovskite-structured samples—HEO-Cr （La（Cr0.2Mn0.2Fe0.2Co0.2Ni0.2）O3），HEO-Cu （La（Mn0.2Fe0.2Co0.2Ni0.2Cu0.2）O3），and HEO-CrSb （La（Cr0.18Mn0.18Fe0.18Co0.18Ni0.18Sb0.1）O3）—were prepared via a template method，while spinel-structured samples—S-HEO-Cr （（Cr0.5Mn0.5Fe0.5Co0.5Ni0.5）O3） and S-HEO-Cu （（Mn0.5Fe0.5Co0.5Ni0.5Cu0.5）O3）—were synthesized by the sol-gel method. Systematic characterizations and analyses of the samples' morphology，structure，composition，valence states，and magnetic properties （including susceptibility-temperature curves （χ-T），hysteresis loops （M-H），and Arrott plots （M2-H/M）） were conducted using scanning electron microscopy （SEM），X-ray diffraction （XRD），X-ray photoelectron spectroscopy （XPS），and physical property measurement system （PPMS）. SEM results showed that elemental doping and structural differences significantly affected the morphology：perovskite samples exhibited nanocubic structures （HEO-Cr was regular，while HEO-Cu showed irregular agglomeration），and spinel samples displayed complex morphologies （S-HEO-Cr formed blocky/polyhedral networks，and S-HEO-Cu presented agglomerated spherical particles）. XRD confirmed that all samples were high-purity single phases：perovskites matched the standard pattern of LaCo0.4Fe0.6O3，and spinels corresponded to NiCr2O4 （S-HEO-Cr） and CuFe2O4 （S-HEO-Cu），indicating good crystallinity. XPS verified the successful incorporation of all designed elements and revealed mixed valence states of Cr （Cr3+/Cr2+） and Cu （Cu/Cu2+）. Magnetic studies demonstrated that Cr and Cu played decisive roles in magnetic types：Cr doping significantly enhanced ferromagnetic （FM） interactions，leading to a high Curie temperature （TC） of 263 K in perovskite HEO-Cr. Its hysteresis loops showed remanence （Mr） and coercivity （Hc） at low temperatures，but the unsaturated behavior at high temperatures indicated competition between FM and antiferromagnetic （AFM） interactions. In contrast，Cu doping strengthened AFM interactions and suppressed long-range magnetic order，reducing TC of HEO-Cu to 86 K，with weak Mr and Hc at low temperatures primarily due to the Jahn-Teller effect of Cu2+（d9）. Introducing Sb into HEO-Cr to form HEO-CrSb drastically decreased TC to 14 K，suggesting that the 5s25p3 electronic configuration of Sb3+/5+ weakened Cr-related FM coupling by altering the electronic structure of B-site ions and enhancing lattice distortion. Crystal structure differences leaded to distinct magnetic behaviors：perovskites exhibited complex magnetic competition （FM/AFM coexistence） due to intricate double-exchange/superexchange interactions among multiple transition metal ions at B-sites，showing obvious phase transitions （FM-paramagnetic，PM） with tunable temperatures （14~263 K）. Spinel samples，however，showed no obvious phase transitions within the tested range and exhibited simpler magnetic behaviors （S-HEO-Cr was ferrimagnetic，and S-HEO-Cu showed unsaturated high-field behavior due to Cu2+），as their geometrically frustrated structures restricted long-range magnetic order. Arrott plot analysis indicated that perovskite samples primarily underwent second-order phase transitions （with possible first-order transitions at low temperatures），while spinel samples showed purely second-order transitions. In summary，this work revealed the internal mechanisms of HEOs' magnetic regulation via Cr/Cu/Sb doping and structural differences. Precisely selecting doping elements and crystal structures can effectively alter magnetic competition and finely tune phase transition temperatures over a wide range （14~263 K），providing critical theoretical and experimental foundations for designing HEOs with specific magnetocaloric properties.
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Basic Information:
DOI：10.13373/j.cnki.cjrm.XY25050002
Chinese Library Classification Number:TB34
Citation Information:
Aiming at the limitations in magnetic regulation of high-entropy oxides （HEOs），this study systematically investigated the influence mechanisms of crystal structures （perovskite and spinel） and elemental doping （Cr，Cu，Sb） on HEOs' magnetic properties. Perovskite-structured samples—HEO-Cr （La（Cr0.2Mn0.2Fe0.2Co0.2Ni0.2）O3），HEO-Cu （La（Mn0.2Fe0.2Co0.2Ni0.2Cu0.2）O3），and HEO-CrSb （La（Cr0.18Mn0.18Fe0.18Co0.18Ni0.18Sb0.1）O3）—were prepared via a template method，while spinel-structured samples—S-HEO-Cr （（Cr0.5Mn0.5Fe0.5Co0.5Ni0.5）O3） and S-HEO-Cu （（Mn0.5Fe0.5Co0.5Ni0.5Cu0.5）O3）—were synthesized by the sol-gel method. Systematic characterizations and analyses of the samples' morphology，structure，composition，valence states，and magnetic properties （including susceptibility-temperature curves （χ-T），hysteresis loops （M-H），and Arrott plots （M2-H/M）） were conducted using scanning electron microscopy （SEM），X-ray diffraction （XRD），X-ray photoelectron spectroscopy （XPS），and physical property measurement system （PPMS）. SEM results showed that elemental doping and structural differences significantly affected the morphology：perovskite samples exhibited nanocubic structures （HEO-Cr was regular，while HEO-Cu showed irregular agglomeration），and spinel samples displayed complex morphologies （S-HEO-Cr formed blocky/polyhedral networks，and S-HEO-Cu presented agglomerated spherical particles）. XRD confirmed that all samples were high-purity single phases：perovskites matched the standard pattern of LaCo0.4Fe0.6O3，and spinels corresponded to NiCr2O4 （S-HEO-Cr） and CuFe2O4 （S-HEO-Cu），indicating good crystallinity. XPS verified the successful incorporation of all designed elements and revealed mixed valence states of Cr （Cr3+/Cr2+） and Cu （Cu/Cu2+）. Magnetic studies demonstrated that Cr and Cu played decisive roles in magnetic types：Cr doping significantly enhanced ferromagnetic （FM） interactions，leading to a high Curie temperature （TC） of 263 K in perovskite HEO-Cr. Its hysteresis loops showed remanence （Mr） and coercivity （Hc） at low temperatures，but the unsaturated behavior at high temperatures indicated competition between FM and antiferromagnetic （AFM） interactions. In contrast，Cu doping strengthened AFM interactions and suppressed long-range magnetic order，reducing TC of HEO-Cu to 86 K，with weak Mr and Hc at low temperatures primarily due to the Jahn-Teller effect of Cu2+（d9）. Introducing Sb into HEO-Cr to form HEO-CrSb drastically decreased TC to 14 K，suggesting that the 5s25p3 electronic configuration of Sb3+/5+ weakened Cr-related FM coupling by altering the electronic structure of B-site ions and enhancing lattice distortion. Crystal structure differences leaded to distinct magnetic behaviors：perovskites exhibited complex magnetic competition （FM/AFM coexistence） due to intricate double-exchange/superexchange interactions among multiple transition metal ions at B-sites，showing obvious phase transitions （FM-paramagnetic，PM） with tunable temperatures （14~263 K）. Spinel samples，however，showed no obvious phase transitions within the tested range and exhibited simpler magnetic behaviors （S-HEO-Cr was ferrimagnetic，and S-HEO-Cu showed unsaturated high-field behavior due to Cu2+），as their geometrically frustrated structures restricted long-range magnetic order. Arrott plot analysis indicated that perovskite samples primarily underwent second-order phase transitions （with possible first-order transitions at low temperatures），while spinel samples showed purely second-order transitions. In summary，this work revealed the internal mechanisms of HEOs' magnetic regulation via Cr/Cu/Sb doping and structural differences. Precisely selecting doping elements and crystal structures can effectively alter magnetic competition and finely tune phase transition temperatures over a wide range （14~263 K），providing critical theoretical and experimental foundations for designing HEOs with specific magnetocaloric properties.
quote
| GB/T 7714-2015 | [1] Miaobing Ruan, Zhaoqiang Li, Xiaobao Zhu, et al. Magnetism of Cr and Cu Doped High-Entropy Oxides[J]. Chinese Journal of Rare Metals, 2026, 50(7): 1124-1136. DOI:10.13373/j.cnki.cjrm.XY25050002. |
| MLA | [1] Miaobing Ruan, et al., "Magnetism of Cr and Cu Doped High-Entropy Oxides." Chinese Journal of Rare Metals, vol. 50, no. 7, 2026, pp. 1124-1136, https://doi.org/10.13373/j.cnki.cjrm.XY25050002. |
| APA | [1] Miaobing Ruan, Zhaoqiang Li, Xiaobao Zhu, Canglong Li, Zexing Cai, & Haibin Sun. (2026). Magnetism of Cr and Cu Doped High-Entropy Oxides. Chinese Journal of Rare Metals, 50(7), 1124-1136. https://doi.org/10.13373/j.cnki.cjrm.XY25050002 |
| IEEE | [1] Miaobing Ruan, Zhaoqiang Li, Xiaobao Zhu, Canglong Li, Zexing Cai, and Haibin Sun, "Magnetism of Cr and Cu Doped High-Entropy Oxides," Chinese Journal of Rare Metals, vol. 50, no. 7, pp. 1124-1136, 2026, doi: 10.13373/j.cnki.cjrm.XY25050002. keywords: {high-entropy oxide;crystal structure;magnetism;curie temperature} |