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The six adiabatic elastic stiffness constants of bismuth and tin have been determined over a range of temperatures extending from room temperature to the melting point. These constants were computed from measurements of the ultrasonic wave velocity in high-purity, single crystal specimens. The constants for bismuth at the melting point are C11 = 56·l C13 = 24·2 C14 = 60 C33 = 34·9 C44 = 90 C66= 16·1 in units of 1010 dynes/cm2. The constants for tin at the melting point (in the same units) are C11 = 61·3 C12 = 38·5 C13 = 38·0 C33 = 75·6 C44 = 16·9 C66 = 19·0.  相似文献   

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The current induced step-like structure in the V-I characteristics of tin whiskers with indium impurities up to 4 at.% shows a zero voltage intercept I0 of approximatively 0.5Ic. This current can be explained by the existence of phase slip centers above the critical current which carry a time averaged supercurrent of ≈0.5Ic. From the differential resistance associated with the first step a “healing length” Ln proportional to l12 (l = mean free path) was obtained which can be related to the quasi-particle diffusion length Λ introduced by Tinkham et al. in the explanation of temperature independent nonequilibrium processes between pairs and quasiparticles at a phase slip center.  相似文献   

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It is shown that for tin, indium and lead samples of sufficiently high purity, sufficiently large diameter (2–3mm), and sufficiently close to the critical temperature (ΔT<0.15K), there exists a common value close to 23(0.64?R(ic)/Rn ? 0.69) of the resistance jump at the transition from the superconducting to the intermediate state.  相似文献   

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The hydrostatic pressure derivatives of the elastic stiffness constants of indium and indium-3.4 at.% cadmium alloy single crystals have been obtained from pulse echo overlap measurements of the dependence of ultrasonic wave velocities upon pressure. The softest zone centre acoustic phonon mode in indium is a shear mode propagating k along the [101] direction rather than that (k[110], e[11?0]) which drives the ferroelastic phase transition in the indium-cadmium alloys. The derivative δ((C11C12)/2)/δP is positive, accounting for the stability of the fct structure of indium under high pressure. Using the quasiharmonic, anisotropic continuum model the acoustic mode Grüneisen parameters have been calculated and are discussed in terms of mode softening. The high temperature limiting value$?γH (= 2.56) of the mean acoustic mode Grüneisen parameter is found to be close to the thermodynamic Grüneisen parameter γth (=2.5).  相似文献   

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A study has been made of the effect of cyclic heat treatment on the density of cadmium having a bismuth admixture. The effects of the heating rate, cooling rate, and time the cadmium is held at the maximum temperature were studied. It is concluded that thermal-structural stresses and admixture enrichment of grain boundaries play an important role in the density changes.Deceased.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 6, pp. 21–27, June, 1969.  相似文献   

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This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide (Ta-doped ITO) films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of $\sim 5.65\times 10^{ - 5}$~$\Omega \cdot$cm$^{2}$ and show the transmittance of $\sim $98% at a wavelength of 440~nm when annealed at 500~\du. Blue light emitting diodes (LEDs) fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21~V at an injection current of 20~mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20~mA in comparison with that of LEDs with conventional Ni/Au contacts.  相似文献   

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β-decay energies of neutron rich tin, antimony and tellurium isotopes with mass numberA=128 and 130 were measured. The results obtained are discussed within the framework of earlier measurements. Additionally nuclear masses deduced from the experimentalQ β -values are compared with mass formulae predictions.  相似文献   

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The surface chemistry of indium tin oxide (ITO) has been investigated with Auger electron spectroscopy (AES) and high resolution electron energy loss spectroscopy (HREELS). A vibrating Kelvin probe (KP) with a graphite reference was used to monitor the absolute work function (Φ) of ITO as a function of chemical modification. The ITO was exposed in situ to molecular hydrogen (H2), hot-filament-activated oxygen (O2*), and hot-filament-activated deuterium (D2*). The initial Φ of ITO was determined to be 5.2 eV, and surface chemical changes had strong effects on this value, as seen by KP. Exposure of clean ITO to O2* increased Φ to 5.6 eV, but the increase was short-lived. The changes in Φ over time were correlated with the uptake of carbon impurities in ultra high vacuum (UHV), as monitored by AES.

The HREELS of ITO revealed significant hydrocarbon impurities. Chemical reduction of ITO produced a metallic surface and dehydrogenated the adsorbed hydrocarbons. Both re-oxidation of metallic ITO and oxidation of clean ITO temporarily removed adventitious carbon from the surface, but oxidized ITO adsorbed an even larger quantity of carbon over time.  相似文献   


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谢卫 《中国物理 B》2008,17(7):2683-2688
This paper reports that indium tin oxide (ITO) crystalline powders are prepared by coprecipitation method. Fabrication conditions mainly as sintering temperature and Sn doping content are correlated with the phase, microstructure, infrared emissivity c and powder resistivity of indium tin oxides by means of x-ray diffraction, Fourier transform infrared, and transmission electron microscope. The optimum sintering temperature of 1350℃ and Sn doping content 6~8wt% are determined. The application of ITO in the military camouflage field is proposed.  相似文献   

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Investigations of ultrasonic velocity and internal friction are carried out in bismuth polycrystals containing Sn, Pb, Sb and Te impurities in the concentration range of 0–1 atomic percent using the composite oscillator technique, and elastic constants are estimated from velocity and density data. The variations of elastic constants are interpreted in terms of changes of lattice parameter, valency of the impurity, the electron-atom ratio, atomic size and Fermi energy. It is observed that the elastic constants are less affected in Bi-Te alloys compared with Bi-Sb, Bi-Pb and Bi-Sn alloys in the above concentration range.  相似文献   

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Silicon nanowires (SiNWs) have been grown on crystalline silicon (Si), indium tin oxide (ITO) and stainless steel (SS) substrates using a gold catalyst coating with a thickness of 200 nm via pulsed plasma-enhanced chemical vapor deposition (PPECVD). Their morphological, mineralogical and surface characteristics have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. SiNWs growth is accompanied by oxidation, thus yielding partially (SiO x ) and fully oxidized (SiO2) Si sheaths. The mean diameters of these SiNWs range from 140 to 185 nm. Si with (111) and (220) planes exists in SiNWs grown on all three substrates while Si with a (311) plane is detected only for Si and ITO substrates. Computational simulation using density functional theory (DFT) has also been conducted to supplement the experimental Raman analyses for crystalline Si and SiO2. XPS results reveal that ca. 30 % of the SiNWs have been oxidized for all substrates. The results presented in this paper can be used to aid selection of appropriate substrates for SiNW growth, depending on specific applications.  相似文献   

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In this work we report the structure and magnetic properties of a series of single-phase indium-substituted yttrium iron garnet (In-YIG) nanoparticles with nominal composition of Y3InxFe5−xO12 (x=0.1, 0.2, 0.3 and 0.4) prepared by conventional mixed oxide route. Based on XRD results, the lattice parameters of the samples increased with increase in In3+ content due to its larger ionic radius. Mössbauer results confirmed the substitution of In3+ for Fe3+ in [a] site of YIG structure. Further, the magnitudes of the magnetic hyperfine field (MHF) were seen to reduce due to indium substitution. Moreover, a rising trend was observed for saturation magnetization (MS) of the samples with x>0.2 owing to the substitution of non-magnetic In3+ for Fe3+. However, the observed initial drop of MS for the sample with x=0.2 compared to that with x=0.1 is possibly attributed to the dominance of spin canting over the net magnetization rise caused by In3+ in [a] sites.  相似文献   

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