Substantially enhanced ferroelectricity in JT ion Cu2+-doped Co1–xCuxCr2O4 (0≤x≤0.4)

Abstract

We investigate the effect of Jahn-Teller (JT) active Cu2+ ions on the structural, magnetic, and ferroelectric properties of Co1–xCuxCr2O4 (0 ≤x≤ 0.4). All the samples can be indexed with a cubic lattice with space group Fd3¯m at room temperature. All the samples undergo a paramagnetic-ferrimagnetic transition at TC and spiral ferrimagnetic ordering at TS. The magnetization measurements manifest that magnetization reversal occurs in the x = 0.2 and 0.3 samples. The x = 0.3 sample possesses a rather large polarization of 14 μC/m2, which is 7 times in magnitude compared with the CoCr2O4 single crystal. The analysis of the infrared active phonon modes implies that two T1u(IR) optical phonon modes are gradually split into a doublet at around 40 K, implying the lowering of lattice symmetry. The presence of a low-symmetry tetragonal phase becomes polar and enhances the electric polarization of Co0.7Cu0.3Cr2O4.

Regulating the Spin State of FeIII Enhances the Magnetic Effect of the Molecular Catalysis Mechanism

“…The significant bands at 617 and 797 cm –1 can be attributed to the shear and stretching vibration of M–O. The changes in the scissoring vibration (δ (M‑O) ) and stretching vibration (υ (M‑O) ) intensities are both related to the embedded Cu 2+ induced by the Jahn–Teller effect . The molar ratios of Fe, Ni, and Cu in different samples were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the results are shown in Figure c and Table S1; the structure composition is roughly consistent with the feeding molar ratio of the reaction, indicating that the NiFe–LDH model catalyst with different doping amounts of Cu 2+ was successfully synthesized.…”

Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters

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Recent advances in catalyst design and activity enhancement induced by a magnetic field for electrocatalysis

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