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31.
In this study, a phase-change memory device was fabricated and the origin of device failure mode was examined using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Ge2Sb2Te5 (GST) was used as the active phase-change material in the memory device and the active pore size was designed to be 0.5 m. After the programming signals of more than 2×106 cycles were repeatedly applied to the device, the high-resistance memory state (reset) could not be rewritten and the cell resistance was fixed at the low-resistance state (set). Based on TEM and EDS studies, Sb excess and Ge deficiency in the device operating region had a strong effect on device reliability, especially under endurance-demanding conditions. An abnormal segregation and oxidation of Ge also was observed in the region between the device operating and inactive peripheral regions. To guarantee an data endurability of more than 1×1010 cycles of PRAM, it is very important to develop phase-change materials with more stable compositions and to reduce the current required for programming. 相似文献
32.
ABSTRACT The adventitious isolation and crystal structure of a pseudorotaxane complex of a trans-substituted dibenzo-27-crown-9-based pyridyl cryptand (6) and N,N’-dimethyl-4,4?-bipyridinium bis(hexafluorophosphate) (5) are reported. 相似文献
33.
A. Yamazaki Y. Inoue M. Koike T. Sakamoto R. Otsuka 《Journal of Thermal Analysis and Calorimetry》1993,40(1):85-97
Thomsonite with ideal chemical composition and with an ordered framework structure was synthesised hydrothermally from zeolite Na?A, which was ground to X-ray amorphous, with 0.05 mol dm?3 CaCl2 solution at 200°C. The dehydration behaviour of the prepared thomsonite was examined by TG-DTA. It was revealed that thomsonite lost most of zeolitic water below 450°C in three steps at about 180°, 340° and 390°C. The peak profiles of, the two higher-temperature endotherms were sharp and similar, and the weight loss at each step was approximately equal. 相似文献
34.
The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34.The results show that the effects of the template and /or water on the coordination of Al atoms are significant,which lead to the formation of various Al species.Up to four kinds of Al species are distinctly resolved. 相似文献
35.
A novel NMR spectrometer is described that is uniquely versatile in its ability to accurately record broad lines by sweeping the superconducting magnetic field and to perform standard high resolution solid state NMR experiments. Broadline observation is illustrated by 27Al spectra from static samples. Such an instrument opens up many nuclei for serious study by NMR in the solid state for the first time. 相似文献
36.
Solid-state nuclear magnetic resonance is used to study the thermal decomposition of lithium tetrahydroaluminate into metallic aluminum, hydrogen and trilithium hexahydroaluminate. Aluminum sites in LiAlH4 and Li3AlH6 were characterized using static, magic angle spinning (MAS) and multiple-quantum MAS NMR. By applying the in situ NMR method, it has been demonstrated that melting is not a prerequisite for the decomposition of LiAlH4. Based on the observed data, a decomposition path has been established that is consistent with the concentrations of observed Al species at various stages of the thermally induced reaction. 相似文献
37.
In this article, we construct a general series for . We indicate that Ramanujan's -series are all special cases of this general series and we end the paper with a new class of -series. Our work is motivated by series recently discovered by Takeshi Sato. 相似文献
38.
We give an algorithm to determine a finite set of generators of the unit group of an order in a non-split classical quaternion algebra over an imaginary quadratic extension K of the rationals. We then apply this method to obtain a presentation for the unit group of . As a consequence a presentation is discovered for the orthogonal group . These results provide the first examples of a characterization of the unit group of some group rings that have an epimorphic image that is an order in a non-commutative division algebra that is not a totally definite quaternion algebra. 相似文献
39.
Philippe?RambourEmail author Abdellatif?Seghier 《Integral Equations and Operator Theory》2004,50(1):83-114
We consider large finite Toeplitz matrices with symbols of the form (1– cos )p f() where p is a natural number and f is a sufficiently smooth positive function. By employing techniques based on the use of predictor polynomials, we derive exact and asymptotic formulas for the entries of the inverses of these matrices. We show in particular that asymptotically the inverse matrix mimics the Green kernel of a boundary value problem for the differential operator
Submitted: June 20, 2003 相似文献
40.
Martine Picavet-L’Hermitte 《Rendiconti del Circolo Matematico di Palermo》2003,52(2):297-307
In questo articolo, si dimostra il legame fra la semi-fattorialità e la fattorialità debole nel contesto degli ordini algebrici.
In particolare, si ottiene che un ordine semi-fattoriale ha il stesso numero di classi che su chiusura integrale. 相似文献