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Based on morphological investigations, as well as on a study of the scanning patterns and diffraction spectra of the heterostructures GaAs-(Ge2)1−x (ZnSe)x, Ge-(Ge2)1−x (ZnSe)x, GaP-(Ge2)1−x (ZnSe)x, and Si-(Ge2)1−x (ZnSe)x, it is shown that the crystal perfection of these structures depends on the choice of the conditions of liquid-phase epitaxy. It is shown that mirror-smooth epitaxial layers of (Ge 2)1−x (ZnSe)x with the lowest stress levels can be obtained on GaAs (100) and Ge (111) substrates. Pis’ma Zh. Tekh. Fiz. 24, 12–16 (January 26, 1998)  相似文献   

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Li X  Kale GM 《Analytical chemistry》2007,79(23):8940-8946
The dense (Ba(x)La(1-x)(2))In(2)O(5+x) electrolytes with different compositions (x = 0.4, 0.5, 0.6) were synthesized by Pechini method. The obtained sintered (Ba(x)La(1-x)(2))In(2)O(5+x) electrolytes showed a high relative density of approximately 98%, and the major phase of three electrolyte compositions was indexed as a cubic phase. The CO sensing properties of as-fabricated planar-type (Ba(x)La(1-x)(2))In(2)O(5+x)-based sensors coupled with ITO and Pt as the sensing electrode and reference electrode, respectively, were investigated. The effects of factors such as gas flow rate, chemical compositions, and density of the electrolytes on the sensing performance were investigated. The sensors showed good sensitivity to different concentrations of CO from approximately 100 to approximately 500 ppm and excellent selectivity over low concentrations of methane (<500 ppm). Linear relationships between emf of the sensors and CO gas concentrations from approximately 100 to approximately 400 ppm were observed. However, the sensors indicated more sluggish response compared with the sensors coupled with a corresponding porous electrolyte. The probable reason has been discussed. The long-term stability of the sensor for the detection of CO was also investigated, which indicated a reasonably stable sensor signal after an initial decline during the incubation period.  相似文献   

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New ternary tellurite glasses in the form (TeO2)50–(V2O5)50−x(TiO2)x have been prepared. Both longitudinal and shear ultrasonic velocities were measured in different compositions of the glass system by using the pulse-echo method at 5 MHz frequency and at room temperature. The elastic properties of ternary telluirte glasses (TeO2)50–(V2O5)50−x(TiO2)x were measured as a function of composition. The ultrasonic velocity data, the density, the calculated elastic moduli, micro-hardness, softening temperature, and Debye temperature depend on the glass composition. By calculating the number of network bonds per unit volume, the average stretching force constant, and the average ring size, information about the structure of the glass can be deduced. Comparison between the calculated and the experimental elastic moduli and Poisson's ratio have been carried out.  相似文献   

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The rational design of Earth abundant electrocatalysts for efficiently catalyzing hydrogen evolution reaction (HER) is believed to lead to the generation of carbon neutral energy carrier. Owing to their fascinating chemical and physical properties, transition metal dichalcogenides (TMDs) are widely studied for this purpose. Of particular note is that doping by foreign atom can bring the advent of electronic perturbation, which affects the intrinsic catalytic property. Hence, through doping, the catalytic activity of such materials could be boosted. A rational synthesis approach that enables phosphorous atom to be doped into WS2 without inducing phase impurity to form WS2(1? x )P2 x nanoribbon (NRs) is herein reported. It is found that the WS2(1? x )P2 x NRs exhibit considerably enhanced HER performance, requiring only ?98 mV versus reversible hydrogen electrode to achieve a current density of ?10 mA cm?2. Such a high performance can be attributed to the ease of H‐atom adsorption and desorption due to intrinsically tuned WS2, and partial formation of NRs, a morphology wherein the exposure of active edges is more pronounced. This finding can provide a fertile ground for subsequent works aiming at tuning intrinsic catalytic activity of TMDs.  相似文献   

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(CuInSe2) x (2ZnSe)1 – x crystals are grown by the horizontal Bridgman process and chemical vapor transport, and their composition and structure are determined. The transmission and reflection spectra of the crystals are measured near the intrinsic edge. The results are used to determine the band gap of the (CuInSe2) x (2ZnSe)1 – x solid solutions, which is found to vary nonlinearly with composition.  相似文献   

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Data are presented on the evolution of the pyrochlore structure in the Ln2+x Hf2?x O7?δ (Ln = Sm, Eu; x = 0.096) solid solutions and Ln2Hf2O7 (Ln = Gd, Tb) compounds prepared from mechanically activated oxide mixtures. Sm2.096Hf1.904O6.952 is shown to undergo pyrochlore-disordered pyrochlore-pyrochlore (P-P1-P) phase transformations in the temperature range 1200–1670°C. The former transformation leads to a rise in 840°C conductivity from 10?4 to 3 × 10?3 S/cm in the samples synthesized at 1600°C, and the latter leads to a drop in 840°C conductivity to 6 × 10?4 S/cm in the samples synthesized at 1670°C. The reduction in the conductivity of Sm2.096Hf1.904O6.952 is accompanied by the disappearance of the assumed superstructure. In the range 1300–1670°C, Eu2+x Hf2?x O7?δ (x = 0.096) and Ln2Hf2O7 (Ln = Gd, Tb) have a disordered pyrochlore structure. The highest 840°C conductivity is offered by Eu2.096Hf1.904O6.952, Gd2Hf2O7, and Tb2Hf2O7 synthesized at 1670°C: 7.5 × 10?3, 5 × 10?3, and 2.5 × 10?2 S/cm, respectively.  相似文献   

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The optical properties of (Ge2)1?x (InP)x solid solutions have been studied by means of ab initio calculations of the electron band structure performed using a self-consistent relativistic scalar full-potential linear muffin-tin orbital method and the density functional theory within the framework of a local charge density approximation.  相似文献   

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The layer type MoSe x Te2−x (0 ≤x ≤ 2) have been grown in single crystalline form by chemical vapour transport technique using bromine as the transporting agent. The electrical resistivity and Hall mobility perpendicular to thec-axis of the crystals were measured at room temperature. The variation of the Seeback coefficient with temperature was also investigated.  相似文献   

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Ternary solid solutions were melt grown from NaCl, KBr and KI starting materials. D.C. and A.C. electrical measurements were done on the resulting ternary compositions at temperatures ranging from 50 to 150 °C. Activation energies and mean jump frequencies were also estimated. The bulk composition has complicated influences on the electrical parameters.  相似文献   

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The quarter-filled π band systems, (DMe-DCNQI)_2M(M=Li1-x Cu x (x ≤ 0.14), Ag) were systematically studied with electron paramagnetic resonance (EPR). The intercolumn spin hopping rate in Li1-x Cu x -salt was obtained from the EPR linewidth. The temperature dependence of can be understood with the hole soliton model which also explains the DC conductivity. The π−d mixing of the Cu-salt enhances both and by 103 times more than the Li-salt, which is consistent with the fact that the only Cu-salt has three-dimensional Fermi surface, but that Ag-salt is one-dimensional in spite of the mixing enhancement of by 10 times more than the Li-salt.  相似文献   

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(HfO2)1 ? x (Sc2O3) x films have been grown by chemical vapor deposition (CVD) using the volatile complexes hafnium 2,2,6,6-tetramethyl-3,5-heptanedionate (Hf(thd)4) and scandium 2,2,6,6-tetramethyl-3,5-heptanedionate (Sc(thd)3) as precursors. The composition and crystal structure of the films containing 1 to 36 at % Sc have been determined. The results demonstrate that, in the composition range 9 to 14 at % scandium, the films are nanocrystalline and consist of an orthorhombic three-component phase, which has not been reported previously. Using Al/(HfO2)1 ? x (Sc2O3) x /Si test structures, we have determined the dielectric permittivity of the films and the leakage current through the insulator as functions of scandium concentration. The permittivity of the films with the orthorhombic structure reaches k = 42–44, with a leakage current density no higher than ~10?8 A/cm2.  相似文献   

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