The multiphase structural evolution and electromagnetic properties driven by Co(iii) ions of La2−xSrxCoMnO6 (x = 0–1.0) polycrystals

This paper reports the structure and order degree changes of double perovskite La2CoMnO6 induced by Sr2+ doping at A-sites (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0), which effectively regulates the electrical and magnetic properties. The evolution of the four-phase structure is from the orthogonal (pbnm, dis...

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Bibliographic Details
Published in:CrystEngComm 2024-09, Vol.26 (38), p.5452-5460
Main Authors: Wang, Xuesong, Song, Hongyuan, Dong, Kun, Yao, Ruihang, Wu, Haorong, Yang, Xiaolong, Chen, Liangwei, Liu, Bin, Ge, Zhenhua, Yu, Lan
Format: Article
Language:English
Subjects:
Cobalt
Coercivity
Doping
Electrical resistivity
Electromagnetic properties
Ferromagnetism
Magnetic moments
Magnetic properties
Perovskites
Polycrystals
Solid phases
Synergistic effect
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Summary:This paper reports the structure and order degree changes of double perovskite La2CoMnO6 induced by Sr2+ doping at A-sites (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0), which effectively regulates the electrical and magnetic properties. The evolution of the four-phase structure is from the orthogonal (pbnm, disordered) and monoclinic (P21/n, ordered) mixed phases of La2CoMnO6 (x = 0) to the rhombohedral (R3c) phase of La1.6Sr0.4CoMnO6, and finally to the cubic phase (Fm3m) of LaSrCoMnO6. All samples exhibit the semiconductor behavior of the three-dimensional variable-range hopping model, and the resistivity decreases first and then increases with increasing Sr content. The low resistivity observed in mixed phases (x = 0.6, 0.8) is primarily attributed to the Co2+ to Co3+ (carrier) transition, the B-site disordering of low structural symmetry, and the p-n type transition. In ferromagnetic La2−xSrxCoMnO6, Sr doping induces the transition from high-spin Co2+ (t2g5eg2) to high-spin Co3+ (t2g4eg2), as well as the superexchange effect from Co2+–O–Mn4+ to Co3+–O–Mn4+. The introduction of a small amount of the cubic phase (x = 0.6) can enhance the bonding energy of the rhombohedral structure, which inhibits the reversal of the magnetic moment, exhibiting a maximum coercive force (Hc = 7.92 kOe). The discovery of rhombohedral and cubic biphase synergistic effect provides a new idea for the modification design of double perovskite materials.
ISSN:1466-8033
DOI:10.1039/d4ce00470a