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Searching low sintering temperature material with ultra-high Curie temperature (>800 °C) is urgent to seafloor hydrothermal vents detection. Bi 2 WO 6 was first improved to possess ultra-high Curie temperature and ultra-high depolarization temperature by experiment. The MnCO 3 was selected as dopant materials due to its excellent effect on improvement of sintering abilities and piezoelectric properties. The density test shows that Mn addition can obviously improve the density of Bi 2 WO 6 ceramics from 93.6% to 97.76%, and the grains also changed from round to layered. The crystal structure change with Mn addition was tested by synchrotron radiation and calculated by ab initio and Rietveld refinement. The symmetry group of ultra-high Curie temperature Bi 2 WO 6 is Aba2 (41). The XAFS results show that Mn atom more likely at the Bi-site in the crystal structure of Bi 2 W 1-x Mn x O 6 and the Mn ion has the valence alternation. The Curie temperature of Bi 2 W 1-x Mn x O 6 with increasing x are 997 °C, 915 °C, 890 °C, 729 °C, respectively, and the depolarization temperatures are around 940 °C, 895 °C, 825 °C, and 700 °C, respectively. The results show that Bi 2 W 1-x Mn x O 6 (x ≤ 0.01) ceramics are suitable for the ultra-high temperature applications of sensors or transducers on seafloor hydrothermal vents detection. [ABSTRACT FROM AUTHOR]

Mn substitution provides perfect perturbation on the local structure and electronic behavior of BiFeO 3. The crystal structure of BiFe 1− x Mn x O 3 (0 ⩽ x ⩽ 0.3) changes from rhombohedral R 3 c to orthorhombic Pbnm via a biphasic region with increasing x . It is found that Mn doping leads to the depolarization of the Bi–O configuration, and the Jahn–Teller distortion of Fe/MnO 6 octahedra. An enhancement of remanent magnetization of BiFe 1− x Mn x O 3 is observed. [ABSTRACT FROM AUTHOR]

Multiferroic BiFe 1- x Zn x O 3 (0 ≤ x ≤ 0.1) powders were synthesized by a hydrothermal method. Structural studies using X-ray diffraction revealed that all samples possessed a rhombohedral R 3 c perovskite structure. Scanning electron microscopy showed that the average grain size decreased slightly with increasing Zn concentration. Fe K -edge and Bi L 3 -edge X-ray absorption fine structure spectra indicated that both the Fe and Bi ions had a +3 valence state in all samples. The local electronic structure of the center atoms was affected by Zn doping. Fourier transform infrared analysis revealed the characteristic vibrations of the obtained BiFe 1- x Zn x O 3 (0 ≤ x ≤ 0.1) samples. Magnetic hysteresis loop measurements indicated a maximum remnant magnetization (M r ) for the x = 0.025 sample, which was primarily a result of the Fe 3+ -O-Zn 2+ anti-ferromagnetic exchange interaction. [ABSTRACT FROM AUTHOR]

The thorough understanding of ORR mechanism provides insights into the design of efficient ORR catalysts. Despite remarkable progress has been made in the development of Cu–N–C ORR catalysts, fundamental understanding of molecular governing factors is still lacking. The carbon matrix with varying π-electron delocalization degree can modulate electron density at the metal ion center rather than merely acting as the electron-conducting path. A volcano relationship is established between oxygen-reduction intrinsic activity and full-width at half-maxima (FWHM) of C 1s photoemission spectra (depicting electron donating/withdrawing capability of carbon matrix to metal ion center). The mechanistic origin of ORR on carbon matrix, N–C sites, and Cu sites in Cu–N–C catalyst in different reaction regions is also illuminated. This work will be likely to offer a new insight in the development of more selective and durable Cu–N–C catalysts for zinc-air batteries. ga1 • Cu moieties can be successfully anchored on mesoporous N-doped carbon. • Mechanism of ORR on carbon matrix, N–C sites, and Cu sites is elucidated. • Cu sites mainly function in diffusion-controlled region. • A volcano relationship is obtained between ORR and FWHM of C 1s for Cu–N–C. • Cu–N–C-900 exhibits the best ORR due to the optimal intermolecular hardness. [ABSTRACT FROM AUTHOR]