Yanjie Wang,Kiyoshi Nomura,Xin Liu,Alexandre I. Rykov,Changzi Jin,Tao Liu,Junhu Wang
Graphical Room-temperature ferromagnetism (RTFM) was found in 57 Fe-TiO 2 and 57 Fe/Sn-TiO 2 materials prepared by a soft-chemical solution method. Their magnetic properties were found to decrease with increasing degree of 57 Fe doping. Fe 3+ –oxygen vacancy (V O )–Fe 3+ centers are responsible for the observed RTFM. A series of 57 Fe-doped TiO 2 and 57 Fe/Sn-codoped TiO 2 materials were prepared by a soft-chemical solution process with various 57 Fe concentrations from 0.1 to 1.0 at.-% and a fixed Sn concentration of 2.0 at.-%. In this process, an aqueous H 2 O 2 solution reacts with iron and titanium or iron, tin, and titanium precursor compounds to produce peroxopolymetallic acids. The structures and magnetic properties of the products were characterized by magnetic-moment measurements, X-ray diffraction, and Raman and Mössbauer spectroscopy. The results showed that all samples consisted of a rutile phase (and a trace amount of anatase in 57 Fe-TiO 2 ). All samples exhibited hysteresis loops in the M – H curves, which demonstrated the presence of room-temperature ferromagnetism. In addition, their magnetic properties decreased with increasing degree of 57 Fe doping. Oxygen vacancies were considered to be responsible for the presence of ferromagnetism.
Ma Kangrui,Wu Jiawen,Wei Derong,Chen Jin,Rong Xuanting,Ding Ruyun,Gu Jia,Ma Xuetiao,Zheng Hui
With the development and use of the electronic and electrical equipment, solving electromagnetic pollution has become a top priority for human health. In this work, ternary co-doped (Ca 2 ⁺, Cu 2 ⁺, Sn 4 ⁺) ions were incorporated into M-type hexagonal barium ferrite (Ba 1-x Ca x Fe 11.6 Cu 0.2 Sn 0.2 O 27 ), and the effects of varying Ca 2 ⁺ doping levels on the crystal structure, surface morphology, and electromagnetic characteristics were thoroughly investigated. Structural characterizations confirms that Ca 2+ substitutes Ba 2+ sites, decreasing the grain size and lattice values while increasing the lattice strain. At x = 0.15, the Ba 1-x Ca x Fe 11.6 Cu 0.2 Sn 0.2 O 27 ferrite achieves the maximum value of saturation magnetization of 67.7 emu/g, the highest RL min value of -44.2 dB@14.3 GHz and effective absorption bandwidth of 3.04 GHz, showing potential as an effective material for absorption applications.
Cu 3 SbSe 4 -based thermoelectric materials , known for their complex crystal structure and splendid Seebeck coefficient , have garnered significant attention. However, a major challenge in this field is further enhancing the thermoelectric performance while effectively controlling the carrier concentration. In this work, a novel doping strategy is proposed to effectively adjust the energy band structure by Mn doping while simultaneously increasing the carrier concentration and the effective mass of the density of states , thereby optimizing the power factor. Additionally, Sn doping is employed to boost the carrier concentration significantly while strengthening the covalent bonds , thereby improving the samples’ stability. As a result, the Cu 3 Sb 0.92 Mn 0.06 Sn 0.02 Se 4 sample achieves a zT value of 0.74 at 673 K. Moreover, the Cu 3 Sb 0.93 Mn 0.06 Sn 0.01 Se 4 sample exhibits an average zT value of 0.39 within the temperature range of 273–675 K. This research sheds light on an approach for designing high-performance Cu 3 SbSe 4 -based thermoelectric materials by manipulating the carrier concentration and enhancing the covalent bond strength through doping.
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