This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the ...This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the change of the applied alternating voltage and measured current are proportional to the microstructural changes at the sample, corresponding to the volume fraction of a series layer model of two phases. To determine the volume fraction of each phase present in the sample, electrical data are obtained: conductivity and permittivity at DC, which are modeled by an electrical circuit composed by 2-RC, taking into that the permittivity and the occupied volume correspond to the filling fraction of each phase. By Cathodic Ersion or Sputtering, samples were obtained in film form of about 500 in thickness, composed of an alloy of Sb2Te3, in amorphous phase. To ensure the existence of the phase transformation in the sample, phase transition tests are performed by changes in: Reflection Optics, Electrical Resistivity and X-Ray Diffraction, showing clearly the presence of such a transformation. In the final part of this work, it completely shows the experimental results, giving a clear and precise idea of the kinetics of phase transformation of Sb2Te3 alloy, by impedance spectroscopy technique, which proves to be a simple and practical calculation tool.展开更多
Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the...Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the well-known equilibrium hexagonal Sb2Te3 crystal, we prove the metastable face-centered cubic Sb2Te3 phase does exist. Such a metastable crystal contains a large concentration of vacancies randomly occupying the cationic lattice sites. The face-centered cubic to hexagonal phase transformation of Sb2Te3, accompanied by vacancy aggregation, occurs at a quite lower temperature compared to that of Ge2Sb2Te5 alloy. We prove that the covalent-like bonds prevail in the metastable Sb2Te3 crystal, deviating from the ideal resonant features. If a proper doping technique is adopted, the metastable Sb2Te3 phase could be promising for realizing reversibly swift and low-energy phase change memory applications. Our study may offer a new insight into commercialized Ge-Sb-Te systems and help in the design of novel phase change materials to boost the performances of the phase change memorv device.展开更多
Topological insulator Sb2Te3 has the advantage of broadband saturable absorption from the visible to the infrared bands.Herein,the two-dimensional material Sb2Te3 saturable absorber(SA)of the topological insulator fam...Topological insulator Sb2Te3 has the advantage of broadband saturable absorption from the visible to the infrared bands.Herein,the two-dimensional material Sb2Te3 saturable absorber(SA)of the topological insulator family was first applied experimentally in a wideband tunable passively Q-switched Yb-doped fiber laser.High-quality Sb2Te3 crystals were synthesized by the flux zone method.The Sb2Te3 SA with fewer layers was further prepared via a modified mechanical exfoliation procedure.Meanwhile,stable wavelength-tunable passive Q-switching pulse operation was obtained in a Yb-doped fiber ring cavity based on the Sb2Te3 SA,where the central wavelength can be continuously tuned from 1040.89 to 1092.85 nm.Results suggest that Sb2Te3 has wideband saturable absorption properties,and that the tunable pulse laser can provide a convenient and simple source for practical applications.展开更多
文摘This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the change of the applied alternating voltage and measured current are proportional to the microstructural changes at the sample, corresponding to the volume fraction of a series layer model of two phases. To determine the volume fraction of each phase present in the sample, electrical data are obtained: conductivity and permittivity at DC, which are modeled by an electrical circuit composed by 2-RC, taking into that the permittivity and the occupied volume correspond to the filling fraction of each phase. By Cathodic Ersion or Sputtering, samples were obtained in film form of about 500 in thickness, composed of an alloy of Sb2Te3, in amorphous phase. To ensure the existence of the phase transformation in the sample, phase transition tests are performed by changes in: Reflection Optics, Electrical Resistivity and X-Ray Diffraction, showing clearly the presence of such a transformation. In the final part of this work, it completely shows the experimental results, giving a clear and precise idea of the kinetics of phase transformation of Sb2Te3 alloy, by impedance spectroscopy technique, which proves to be a simple and practical calculation tool.
基金This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences （No. XDA09020402）, National Integrate Circuit Research Program of China （No. 2009ZX02023-003）, National Natural Science Foundation of China （Nos. 61076121, 61176122, 61106001, 61261160500, and 61376006）, Science and Technology Council of Shanghai （Nos. 13ZR1447200 and 13DZ2295700）. The supercomputer time was provided by the National Supercomputer Center in Tianjin, and the calculations were performed on TianHe-1 （A）.
文摘Although phase change memory technology has developed drastically in the past two decades, the cognition of the key switching materials still ignores an important member, the face-centered cubic Sb2Te3. Apart from the well-known equilibrium hexagonal Sb2Te3 crystal, we prove the metastable face-centered cubic Sb2Te3 phase does exist. Such a metastable crystal contains a large concentration of vacancies randomly occupying the cationic lattice sites. The face-centered cubic to hexagonal phase transformation of Sb2Te3, accompanied by vacancy aggregation, occurs at a quite lower temperature compared to that of Ge2Sb2Te5 alloy. We prove that the covalent-like bonds prevail in the metastable Sb2Te3 crystal, deviating from the ideal resonant features. If a proper doping technique is adopted, the metastable Sb2Te3 phase could be promising for realizing reversibly swift and low-energy phase change memory applications. Our study may offer a new insight into commercialized Ge-Sb-Te systems and help in the design of novel phase change materials to boost the performances of the phase change memorv device.
基金Project supported by the National Natural Science Foundation of China(Nos.61875223 and 61801472)the Hunan Province Key Area Research and Development Plan(No.2019GK2181)+1 种基金the Hunan Provincial Innovation Project(No.2019RS3017)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Nos.B200203143 and KYCX20_0433)。
文摘Topological insulator Sb2Te3 has the advantage of broadband saturable absorption from the visible to the infrared bands.Herein,the two-dimensional material Sb2Te3 saturable absorber(SA)of the topological insulator family was first applied experimentally in a wideband tunable passively Q-switched Yb-doped fiber laser.High-quality Sb2Te3 crystals were synthesized by the flux zone method.The Sb2Te3 SA with fewer layers was further prepared via a modified mechanical exfoliation procedure.Meanwhile,stable wavelength-tunable passive Q-switching pulse operation was obtained in a Yb-doped fiber ring cavity based on the Sb2Te3 SA,where the central wavelength can be continuously tuned from 1040.89 to 1092.85 nm.Results suggest that Sb2Te3 has wideband saturable absorption properties,and that the tunable pulse laser can provide a convenient and simple source for practical applications.
