Bi1-xYbxFeO3（0〈x〈0.2） powders have been synthesized using a sol-gel method. The X- ray diffraction data show a structural transition from the rhombohedral R3c phase to the orthorhombic Pnma phase between x=0.1 and...Bi1-xYbxFeO3（0〈x〈0.2） powders have been synthesized using a sol-gel method. The X- ray diffraction data show a structural transition from the rhombohedral R3c phase to the orthorhombic Pnma phase between x=0.1 and 0.125, which should induce a ferroelectric- paraelectric transformation. The phase transition is also proven by the Raman spectroscopy. A moderate signal on magnetization appears to illustrate the enhancement of magnetization at the transformation boundary, which is suggested to be the destruction of the spin cycloid structure at low concentration. The appearance of antiferromagnetic ordering is proposed to account for the afterward reduction of the magnetization at high concentration.展开更多
Porous FeAl-based intermetallics were fabricated by thermal explosion（TE） from Fe and Al powders. The effects of sintering temperature on phase constitution, pore structure and oxidation resistance of porous Fe-Al i...Porous FeAl-based intermetallics were fabricated by thermal explosion（TE） from Fe and Al powders. The effects of sintering temperature on phase constitution, pore structure and oxidation resistance of porous Fe-Al intermetallics were systematically investigated. Porous Fe-Al materials with high open porosity（65%） are synthesized via a low-energy consumption method of TE at a temperature of 636 ℃ and FeAl intermetallic is evolved as dominant phase in sintered materials at 1000 ℃. The porous materials are composed of interconnected skeleton, large pores among skeleton and small pores in the interior of skeleton. The interstitial pores in green powder compacts are the important source of large pores of porous Fe-Al intermetallics, and the in-situ pores from the melting and flowing of aluminum powders are also significant to the formation of large pores. Small pores are from the precipitation of Fe-Al intermetallics particles. In addition, the porous specimens exhibit high resistance to oxidation at 650 ℃ in air.展开更多
Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multi...Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,respectively.To address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy analysis.In summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.展开更多
基金This work was supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project, the Ministry of Education of China （No.708070）, the National Natural Science Foundation of China （No.10874046 and No.11104081）, and the Fundamental Research Funds for the Central Universities （No.2012zz0078）.
文摘Bi1-xYbxFeO3（0〈x〈0.2） powders have been synthesized using a sol-gel method. The X- ray diffraction data show a structural transition from the rhombohedral R3c phase to the orthorhombic Pnma phase between x=0.1 and 0.125, which should induce a ferroelectric- paraelectric transformation. The phase transition is also proven by the Raman spectroscopy. A moderate signal on magnetization appears to illustrate the enhancement of magnetization at the transformation boundary, which is suggested to be the destruction of the spin cycloid structure at low concentration. The appearance of antiferromagnetic ordering is proposed to account for the afterward reduction of the magnetization at high concentration.
基金Project(51574241)supported by the National Natural Science Foundation of ChinaProject(51611130064)supported by the Bilateral Project of NSFC-STINTProject(2015QN004)supported by the Program for Innovation Research Team of China University of Mining and Technology
文摘Porous FeAl-based intermetallics were fabricated by thermal explosion（TE） from Fe and Al powders. The effects of sintering temperature on phase constitution, pore structure and oxidation resistance of porous Fe-Al intermetallics were systematically investigated. Porous Fe-Al materials with high open porosity（65%） are synthesized via a low-energy consumption method of TE at a temperature of 636 ℃ and FeAl intermetallic is evolved as dominant phase in sintered materials at 1000 ℃. The porous materials are composed of interconnected skeleton, large pores among skeleton and small pores in the interior of skeleton. The interstitial pores in green powder compacts are the important source of large pores of porous Fe-Al intermetallics, and the in-situ pores from the melting and flowing of aluminum powders are also significant to the formation of large pores. Small pores are from the precipitation of Fe-Al intermetallics particles. In addition, the porous specimens exhibit high resistance to oxidation at 650 ℃ in air.
基金supported by the National Natural Science Foundation of China(62174065)the Key Research and Development Plan of Hubei Province(2020BAB007)+1 种基金Hubei Provincial Natural Science Foundation(2021CFA038)the support from Hubei Key Laboratory of Advanced Memories&Hubei Engineering Research Center on Microelectronics。
文摘Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,respectively.To address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy analysis.In summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.
