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| 1 | High-frequency MnZn soft magnetic ferrite by engineering grain boundaries with multiple-ion doping显示文摘MnZn soft magnetic ferrites have been widely utilized in power electronics,owing to the combined merits of high permeability and low energy loss.However,their deployment would result in a drastic increase in power dissipation at>3 MHz,thus limiting the scope extent of miniaturization,together with their efficiency.Here,we report a high-performance MnZn ferrite by doping multiple ions(La,Ti,Si,Ca)at grain boundaries,achieving the most optimized power loss of 267 kW/m^(3) at 5 MHz(10 m T,100℃)and initial permeability of 644,which is much better than the previously reported results and commercial products.Such an improvement is attributed to weakened magnetic exchange coupling at grain-boundary regions,associated with a significant transition from the multi-to mono-domain structures,originating physically from large crystallographic mis-orientations(>25°).The present study bears important significance in understanding the intrinsic correlation between the crystallographic mis-orientation and magnetic domain structure,and provides an alternative way for optimizing high-frequency soft magnetic ferrites. | Mi Yan Shengbo Yi Xiuyuan Fan Zhenghua Zhang Jiaying Jin Guohua Bai | 2021 | Journal of Materials Science & Technology2021，，20： | 2 |
| 2 | Seed,cutting and air-layering reproductive inefficiency of noxious woody vine Merremia biosiana and its implications for management strategy显示文摘Merremia boisiana(Gagnep)van Ooststr.is a noxious fast growing woody vine and is able to grow overtop other plants,causing the death of plants underneath and forming monospecies stands.To formulate management responses,we assessed its seed and vegetative reproduction efficacy through indoor and field experiments.The number of flowers counted from bagged infructescences in Guangzhou ranged from 25 to 172,with an average of 80.80.Counting the seeds of bagged infructescences had shown that there were only 1.58 hard testa seeds in each infructescence.Seed vitality tests using red ink indicated that only 68.6%of hard testa and filled seeds were viable.The emergence rate of scarified hard testa seeds in the sand bed was 31.96%.Under imitated natural conditions,8%of hard testa seeds could germinate,and 9%still retained their germination potential in one year.Thus,seedlings should be monitored and removed in a timely fashion after any attempt of clearing.Moving soil or transplanting plant from infested patches should be strictly prohibited at least for several years.All considered,an infructescence contributed 0.3 seedlings.The investigation in the field found no seedlings either inside or at the perimeter of the patch,suggesting scant expansion by means of seed dispersal.Therefore,the elimination effort could be focused on a relatively restricted scale of patches.Of 630 cuttings of young shoots,old shoots and old lying shoots with or without growth regulators,there were only four(or 0.63%)established individuals.Air-layering shoots all died in two months.Poor cuttings and airlayering reproduction indicated that regeneration from fragments of removed stems or accidentally dropped ones was quite unlikely,and thus mechanical removal was safe. | Mingguang LI Haiyang LIU Fenglan LI Xiuyuan CHENG Bin GUO Zhiwei FAN | 2009 | Frontiers in Biology2009，4，3： | 1 |
| 3 | Synergistic effect of V_(2)O_(5)and Bi_(2)O_(3) on the grain boundary structure of high-frequency NiCuZn ferrite ceramics显示文摘High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss(Pcv)at megahertz frequencies.Here,we prepared NiCuZn ferrite with superior high-frequency properties by V_(2)O_(5)and Bi_(2)O_(3)synergistic doping,which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies.The sample doped with 800 ppm V_(2)O_(5)and 800 ppm Bi_(2)O_(3)yielded the most optimized magnetic properties with a Pcv of 113 kW/m^(3)(10 MHz,5 mT,25℃),an initial permeability(μi)of 89,and a saturation induction(Bs)of 340 mT,which is at the forefront of the reported results.These outstanding properties are closely related to the notable grain boundary structure,which features a new type of nano-Bi_(2)Fe_(4)O_(9)phase around ferrite grains and a Ca/Si/V/O amorphous layer.Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites. | Xiuyuan FAN Guohua BAI Zhenhua ZHANG Qiming CHEN Jiaying JINa Jiafeng XUa Xuefeng ZHANG Mi YAN | 2022 | Journal of Advanced Ceramics2022，11，6： | 0 |
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