排序方式: 共有22条查询结果,搜索用时 15 毫秒
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We report a pressure-dependent investigation of KMnF(3) by x-ray diffraction up to 30 GPa. The results are discussed in the framework of Landau theory and in relation to the isostructural phase transition in SrTiO(3). The phase transition temperature near 186 K in KMnF(3) shifts to room temperature at a critical pressure of P(c) = 3.4 GPa; the pressure dependence of the transition point follows ΔP(c)/ΔT(c) = 0.0315 GPa K(-1). The transition becomes second order under high pressure, close to the tricritical point. The phase transition is determined by the rotation of MnF(6) octahedra with their simultaneous expansion along the rotation axis. The rotation angle was found to increase to 10.5° at 24 GPa. An additional anomaly was observed at higher pressure around 25 GPa, suggesting a further phase transition. 相似文献
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Actis P Manesse M Nunes-Kirchner C Wittstock G Coffinier Y Boukherroub R Szunerits S 《Physical chemistry chemical physics : PCCP》2006,8(42):4924-4931
This paper describes the functionalization of oxidized boron-doped diamond (BDD) electrodes with N-(3-trimethoxysilylpropyl)pyrrole (TMPP) and the influence of this layer on the electrochemical transfer kinetics as well as on the possibility of forming strongly adhesive polypyrrole films on the BDD interface through electropolymerization. Furthermore, localized polymer formation was achieved on the TMPP-modified BDD interface using the direct mode of a scanning electrochemical microscope (SECM) as well as an electrochemical scanning near-field optical microscope (E-SNOM). Depending on the method used polypyrrole dots with diameters in the range of 1-250 microm are electrogenerated. 相似文献
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Mael Guennou Hichem Dammak Philippe Djémia Philippe Moch Pham-Thi Mai 《Solid State Sciences》2010,12(3):298-301
In this paper, we compare the electromechanical properties of tetragonal single domain PZN–12%PT single crystals obtained by different methods: resonance–antiresonance method, Brillouin scattering, and resonant ultrasound spectroscopy. The agreement between the different measurements is found satisfactory for many elastic constants within experimental uncertainties. Differences are notable for the elastic constants associated to the propagation of shear waves (c66E and c44E). This can be accounted for by imperfections of the sample in acoustic spectroscopy and specific difficulties of shear resonators used for the resonance method. Strong discrepancies are noted for the hardened elastic constant c33D associated to longitudinal waves propagating along the polarization direction; we suggest this can arise from a frequency dependence of the dielectric constant. 相似文献
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M. Boratav J. Le Guyader M. Sene
J. Ginestet
D. Manesse Tran Ha Anh D. VignaudJ. Bartke
《Nuclear Physics B》1970,20(3):573-591We present here an analysis of the reaction pp→ppπ+π− at 8.1 GeV/c in terms of the two multi-Regge models proposed by Chan,
;oskiewicz and Allison and by Berger et al. in which we introduce some modifications to improve the agreement between experimental data and theoretical results. Comparison between various experimental distributions and corresponding theoretical curves is satisfactory with a very simple parametrization in both models. 相似文献
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Mael Guennou Maxim Savinov Jan Drahokoupil Haosu Luo Jirka Hlinka 《Applied Physics A: Materials Science & Processing》2014,116(1):225-228
We report a study of properties of Mn-doped NBT-6 %BT single crystals. We show that tetragonal single-domain states can be stabilized by poling along a [001] direction. For carefully prepared crystals, the piezoelectric coefficient \(d_{33}\) can reach 570 pC/N. When poled along non-polar directions, the crystals exhibit ferroelectric domain structures consistent with tetragonal micron-sized domains, as revealed by optical observation and Raman spectroscopy. The multidomain crystals have lower \(d_{33}\) values, 225 and 130 pC/N for [011] and [111]-oriented crystals, respectively. This trend is commented on from a domain-engineering perspective. 相似文献
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Darmanin T Nicolas M Guittard F 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9739-9746
The electrochemical deposition of organic materials is a convenient and straightforward method that affords rough films in mild conditions. The presence of fluorinated chains covalently attached on the polymer backbone allows the control of the second criterion which plays a role on the wetting properties of the surface, that is, the chemical composition. By modification of the nature of the polymer, films with different surface energies were obtained. Thus, original semifluorinated polypyrrole (PPy- RF n ), polyfluorene (PFl- RF n ), and polyethylenedioxythiophene (PEDOT- RF n ) have been chemically and electrochemically synthesized and characterized. On one hand, the chemical polymerization affords highly fluorinated soluble polymers. Soluble PFl- RF n exhibits blue fluorescence in solution while soluble PEDOT- RF n presents optical properties similar to those of PEDOT. Consequently, they represent interesting candidates for optical devices (OLEDs for PFl- RF n , electrochromic materials for PEDOT- RF n ). On the other hand, surface properties have been investigated on the electroformed polymers by goniometry and microscopy. Fluorinated surfaces of electrodeposited polypyrrole, like polythiophene, give birth to high hydrophobic and oleophobic surfaces, while the use of polyethylenedioxythiophene as the polymer increases sufficiently the surface energy to get combined superhydrophobicity and superoleophilicity. The influence of the chemical composition is discussed through the comparison of the wetting properties of polyethylenedioxythiophene and semifluorinated polythiophene and polyethylenedioxythiophene. 相似文献
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Electrodeposited films of poly(ethylenedioxythiophene) (PEDOT) present a rough morphology and are wettable by water and oil. The covalent binding of low free energy fluorinated chains on the monomer before polymerization lowers the surface energy of the electroformed polymers sufficiently to give rise to superhydrophobic behaviour while conserving superoleophilicity. It holds the promise of an interesting candidate for the separation of water and oil. 相似文献