Search

CuO 6 octahedra usually show elongated distortion, leading to active d x 2 -y 2 orbitals and planar exchange interactions, while compressed CuO 6 octahedra with active d 3 z 2 - r 2 orbitals and unidirectional exchange interactions are exceptionally rare. Here, we design and synthesize a new frustrated antiferromagnet CaCuFe 2 O 5 through a high-pressure and high-temperature approach, in which robust compressed CuO 6 octahedra are realized, separating the Fe 2 O 5 sheets that comprise zigzag spin ladders. Magnetic susceptibility and specific heat measurements exhibit a long-range antiferromagnetic order below the Néel temperature of 165 K, which is further confirmed by neutron diffraction. Detailed magnetic refinement reveals a C-type spin structure, with its spin arrangement and orientation distinct from that of the isostructural CaFe 3 O 5 . By constructing a Heisenberg model, we find that this is due to the exchange redistribution between the CuO 6 octahedra and Fe 2 O 5 sheets, during which some of the exchange interactions are selectively annihilated due to the specific orientation of the Cu d 3 z 2 - r 2 orbitals in the compressed CuO 6 octahedra. Our results provide a unique example of robust compressed CuO 6 octahedra and show that it can selectively annihilate some of the exchange interactions and completely modify the spin structure and magnetic frustration accordingly.

CaCu 3 Fe 2 Re 2 O 12 and LaCu 3 Fe 2 Re 2 O 12 quadruple perovskite oxides are well known for their high ferrimagnetic Curie temperatures and half-metallic electronic structures. By A-site chemical substitution with lower valence state Na + , an isostructural compound NaCu 3 Fe 2 Re 2 O 12 with both A- and B-site ordered quadruple perovskite structures in Pn -3 symmetry was prepared using high-pressure and high-temperature techniques. The X-ray absorption study demonstrates the valence states to be Cu 2+ , Fe 3+ , and Re 5.5+ . A ferrimagnetic phase transition is found to take place at the Curie temperature T C ≈ 240 K, which is much less than that observed in A = Ca (560 K) and La (710 K) analogues. NaCu 3 Fe 2 Re 2 O 12 possesses a larger saturated magnetic moment up to 9.4 μ B /f.u. as well as a remarkably reduced coercive field less than 10 Oe at 2 K. Theoretical calculations suggest that NaCu 3 Fe 2 Re 2 O 12 displays a half-metallic electronic band structure with complete spin polarization of conduction electrons in the minority-spin bands. The magnetic properties and electronic structures of the ACu 3 Fe 2 Re 2 O 12 family are compared and discussed.

Polymerizable deep eutectic solvents (PDESs) have emerged as promising building blocks for next-generation eutectic gels, offering new opportunities for the development of advanced electronic devices. Traditional PDES fabrication typically involves heating and extended processing time. In this study, a facile method where a solid-solid mixture of lithium bis(trifluoromethane) sulfonimide (LiTFSI) and acrylamide (AAm) rapidly forms a PDES at room temperature, significantly simplifying the ionogel preparation is presented. By combining this PDES with another system, comprising 3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (SBMA) and ethylene glycol (EG), an eutectic gel is successfully fabricated with exceptional mechanical and conductive properties. This gel exhibits a fracture stress of 0.8 MPa, fracture energy of 3.7 kJ m -2 , adhesion strength of 60 kPa, transmittance over 90%, high conductivity (0.113 S m -1 ), and an outstanding temperature tolerance ranged from -50 to 50 °C. Notably, the absence of chemical crosslinkers and the presence of reversible interactions such as hydrogen bonding and ion-dipole electrostatic forces impart excellent self-healing capabilities. These combined features position the gel a promising candidate for multisensory ionic skins, capable of detecting pressure, temperature, humidity, and sweat. This work pioneers the rapid, mild-condition synthesis of PDESs, paving the way for new techniques in ionic skin development., (© 2024 Wiley‐VCH GmbH.)