Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It...Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 phases.Diffusive enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.展开更多
SmConanoparticles(NPs) have promising applications in high-density magnetic storage and magnetic nanocomposites. In this work, A novel method to yield SmCoparticles with small size and high coercivity was reported. Fi...SmConanoparticles(NPs) have promising applications in high-density magnetic storage and magnetic nanocomposites. In this work, A novel method to yield SmCoparticles with small size and high coercivity was reported. Firstly, SmO-Co NPs with size of 6-15 nm were fabricated by a solvothermal route. Then the agglomerated SmCoparticles were obtained by thermal reduction of the precursor, which show high coercivity of2.0 T at room temperature. At last, the as-synthesized SmCoparticles were further hydrogenated under high hydrogen pressure of 4 MPa at room temperature, where hydrogen absorption process could form small-sized SmCoHparticles due to their lattice expansion and hydrogen desorption process could convert SmCoHNPs into SmCoNPs. The prepared SmCoNPs after hydrogenation, showing well distribution, have a small size of5-20 nm and room temperature coercivity of 1.22 T.展开更多
A three-step chemical synthesis of SmCo5/Co nanocomposites was developed. Firstly, the Co-Sm（OH）3-Ca（OH）2 precursors were prepared by co-precipitation.Secondly, SmCo5 particles were obtained by reductive annealing...A three-step chemical synthesis of SmCo5/Co nanocomposites was developed. Firstly, the Co-Sm（OH）3-Ca（OH）2 precursors were prepared by co-precipitation.Secondly, SmCo5 particles were obtained by reductive annealing of the precursors. At last, the SmCo5/Co nanocomposites were achieved by chemical deposition based on SmCo5 particles. The SmCo5/Co nanocomposites contain hard magnetic phase of SmCo5 with about 100 nm in size and soft magnetic phase of Co with about 8 nm in size,exhibiting independent two-phase structure without alloying. Compared to that of single-phase SmCo5 particles, the saturation magnetization of SmCo5/Co nanocomposites is increased by 27.5%. The synthesis provides a new route to fabricate SmCo-based nanocomposites.展开更多
基金Project supported by BRICSSTI Framework Program for Basic Research(RFBR-BRICS)(17-52-80072)DST-BRICS,and the State Assignment of Ministry of Science and Education of Russia(topic “Magnet)(AAAA-A18-118020290129-5)
文摘Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 phases.Diffusive enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.
基金State Key Development Program of Basic Research of China(2010CB934600)The Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality
基金financially supported by the National Natural Science Foundations of China (Nos. 51471016 and 51520105002)the Key Natural Science Foundation of Beijing (No. 2151002)
文摘SmConanoparticles(NPs) have promising applications in high-density magnetic storage and magnetic nanocomposites. In this work, A novel method to yield SmCoparticles with small size and high coercivity was reported. Firstly, SmO-Co NPs with size of 6-15 nm were fabricated by a solvothermal route. Then the agglomerated SmCoparticles were obtained by thermal reduction of the precursor, which show high coercivity of2.0 T at room temperature. At last, the as-synthesized SmCoparticles were further hydrogenated under high hydrogen pressure of 4 MPa at room temperature, where hydrogen absorption process could form small-sized SmCoHparticles due to their lattice expansion and hydrogen desorption process could convert SmCoHNPs into SmCoNPs. The prepared SmCoNPs after hydrogenation, showing well distribution, have a small size of5-20 nm and room temperature coercivity of 1.22 T.
基金financially supported by the National Natural Science Foundation of China (No. 51471016)the Key Natural Science Foundation of Beijing (No. 2151002)
文摘A three-step chemical synthesis of SmCo5/Co nanocomposites was developed. Firstly, the Co-Sm（OH）3-Ca（OH）2 precursors were prepared by co-precipitation.Secondly, SmCo5 particles were obtained by reductive annealing of the precursors. At last, the SmCo5/Co nanocomposites were achieved by chemical deposition based on SmCo5 particles. The SmCo5/Co nanocomposites contain hard magnetic phase of SmCo5 with about 100 nm in size and soft magnetic phase of Co with about 8 nm in size,exhibiting independent two-phase structure without alloying. Compared to that of single-phase SmCo5 particles, the saturation magnetization of SmCo5/Co nanocomposites is increased by 27.5%. The synthesis provides a new route to fabricate SmCo-based nanocomposites.
