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排序方式: 共有354条查询结果,搜索用时 15 毫秒
181.
182.
E. Illeková D. Janičkovič M. Miglierini I. Škorvánek P. Švec 《Journal of magnetism and magnetic materials》2006
Amorphous Fe-Mo-Cu-B ribbons with varying Fe/B ratio were prepared by planar flow casting. Characteristic transformation temperatures as well as the transformation kinetics were determined by DTA and DSC analyses. The presence of magnetic phases was identified by VSM-magnetometry; the information about their local ordering was obtained using Mössbauer spectrometry. Structure analysis was performed by X-ray diffraction analysis and by transmission electron microscopy. In all cases, higher bcc-Fe crystallization temperatures and lower magnetization of crystalline samples are observed with increasing content of boron. 相似文献
183.
A. Rebey B. El Jani A. Leycuras S. Laugt P. Gibart 《Applied Physics A: Materials Science & Processing》1999,68(3):349-352
20 cm-3 and above) induce oscillations in the reflected intensity.
The evolution of the layers morphology is shown to depend on two effects: (i)the locally high surface concentration of carbon
which blocks locally the growth and hence induces holes at the surface, (ii)the occurrence of dislocations at thicknesses
larger than the critical thickness which are revealed chlorides produced by the decomposition of CCl4 (the carbon precursor) and form deep etch pits.
Received: 13 February 1998 / Accepted: 26 October 1998 相似文献
184.
The structural and magnetic properties of the mixed spinel Mg1+xMnxFe2-2xO4 system for 0.1<= x <= 0.9 have been studied by means of X-ray diffraction, magnetization, a.c. susceptibility and Mössbauer spectroscopy measurements. X-ray intensity calculations indicate that Mn4+ ions occupy only octahedral (B) sites replacing Fe3+ ions and the added Mg2+ ions substitute for A-site Fe3+ ions. All samples are magnetic at 12 K displaying Mössbauer spectra that have magnetic sextets coexisting with a central doublet that increases in population with increasing Mn concentration, indicating the presence of short range ordering (clustering). The Mössbauer intensity data show that Mn possesses a preference for the B-site of the spinel over the whole range of concentration. As expected, the hyperfine field and Curie temperature determined from a.c.susceptibility data decrease with increasing Mn content. Magnetization results indicate that on increasing dilution x, the collinear ferrimagnetic phase breaks down at x = 0.3 before reaching the ferrimagnetic percolation limit (x=0.6), as a result of the presence of competing exchange interactions, which is well supported by Mössbauer results. From all the above results, it is proposed that with increasing Mn content from x=0.6 to 0.9, the frustration and disorder increase in the system suppressing the ferrimagnetic ordering, and the system approaches to a cluster spin glass type of ordering at x=0.8 as reflected in the a.c.susceptibility and Mössbauer spectrum. 相似文献
185.
186.
Jani Reddy Bolla Robin A. Corey Cagla Sahin Joseph Gault Alissa Hummer Jonathan T. S. Hopper David P. Lane David Drew Timothy M. Allison Phillip J. Stansfeld Carol V. Robinson Michael Landreh 《Angewandte Chemie (International ed. in English)》2020,59(9):3523-3528
Membrane proteins engage in a variety of contacts with their surrounding lipids, but distinguishing between specifically bound lipids, and non‐specific, annular interactions is a challenging problem. Applying native mass spectrometry to three membrane protein complexes with different lipid‐binding properties, we explore the ability of detergents to compete with lipids bound in different environments. We show that lipids in annular positions on the presenilin homologue protease are subject to constant exchange with detergent. By contrast, detergent‐resistant lipids bound at the dimer interface in the leucine transporter show decreased koff rates in molecular dynamics simulations. Turning to the lipid flippase MurJ, we find that addition of the natural substrate lipid‐II results in the formation of a 1:1 protein–lipid complex, where the lipid cannot be displaced by detergent from the highly protected active site. In summary, we distinguish annular from non‐annular lipids based on their exchange rates in solution. 相似文献
187.
Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz: electron-phonon coupling
strength λ. Coulomb pseudopotential μ*, transition temperature T
c, isotope effective exponent α and interaction strength N
0
V for the In1−x
Zn
x
and In1−x
Sn
x
binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor,
Vashistha-Singwi, Ichimaru-Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange
and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging,
which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture. 相似文献
188.
I. Halidou Z. Benzarti Z. Bougrioua T. Boufaden B. El Jani 《Superlattices and Microstructures》2006,40(4-6):490
GaN has been grown using Si/N treatment growth by MOVPE on sapphire (0001) in a home-made vertical reactor. The growth was monitored by in situ laser reflectometry. The morphological, electrical and optical properties of GaN are investigated at all the growth stages. To this aim, the growth was interrupted at different stages. The obtained samples are ex situ characterized by scanning electron microscopy (SEM), room temperature Van der Pauw–Hall electrical transport and low temperature (13 K) photoluminescence (PL) measurements. The SEM images show clearly the coalescence process. A smooth surface is obtained for a fully coalesced layer. During the coalescence process, the electron concentration (n) and mobility (μ) vary from 2×1019 cm−3 to 2×1017 cm−3 and 12 cm2/V s–440 cm2/V s, respectively. The PL maxima shift to higher energy and the FWHM decreases to about 4 meV. A correlation between PL spectra and Hall effect measurements is made. We show that the FWHM follows a n2/3 power law for n above 1018 cm−3. 相似文献
189.
190.
Rajiv Vaidya Neha Bhatt S. G. Patel A. R. Jani Alka B. Garg V. Vijayakumar B. K. Godwal 《Pramana》2003,61(1):183-186
The results of electrical resistance measurements under pressure on single crystals of WSe2 are reported. Measurements up to 8.5 GPa are carried out using Bridgman anvil set up and beyond it using diamond anvil cell
(DAC) up to a pressure of 27 GPa. There is no clear indication of any phase transition till the highest pressure is reached
in these measurements. 相似文献