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1.
General features of ecological control in nanotechnologies were found. Based on the study of structural-morphological characteristics of nanoprecipitates with ordered structure in Ca y La1 ? y F3 ? y and La x Ca1 ? x F2 + x , it was shown that it is necessary to additionally control the formation of ordered states, the presence of antiphase domains, and the degree of order in ecological control of solution-based materials.
相似文献2.
P. V. Seredin E. P. Domashevskaya I. N. Arsentyev D. A. Vinokurov A. L. Stankevich 《Semiconductors》2013,47(1):7-12
The growth of epitaxial Al x Ga1 ? x As:C alloys by metal-organic chemical vapor deposition (MOCVD) at low temperatures results in the formation of quaternary (Al x Ga1 ? x As)1 ? y C y alloys, in which carbon atoms can be concentrated at lattice defects in the epitaxial alloy with the formation of impurity nanoclusters. 相似文献
3.
Sr2La3Nb1?x Ta x Ti4O17 (0 ≤ x ≤ 1) ceramics were processed via a solid-state mixed oxide route. Sr2La3Nb1?x Ta x Ti4O17 (0 ≤ x ≤ 1) solid solutions were single phase in the whole range of x values within the x-ray diffraction (XRD) detection limit. The microstructure comprised elongated and needle-shaped grains. The ceramics exhibit relative permittivity (ε r) of 73 to 68.6, product of unloaded quality factor and resonant frequency (Q u f 0) of 7100 GHz to 9500 GHz, and temperature coefficient of resonant frequency (τ f) of 78.6 ppm/°C to 56.6 ppm/°C. 相似文献
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Using Cu-phthalocyanine(CuPc),4,4’-diaminodiphenyl ether and pyromellitic dianhydride as monomer materials, polyimide(PI) thin films doped-CuPc have been prepared onto glass substrate by vapor phase co-deposition polymerization under a vacuum of 2×10~(-3)Pa and thermal curing of polyamic acid film in at temperature of 150-200℃ for 60min. In this process, the polymerization can be carried out through controlling the stoichiometric ratio, heating time and deposition rates of the three monomers. IR spectrum identifies the designed chemical structure of the polymer. The absorption of polyimide doped-CuPc is very intense in vis-range and near-infrared by UV-Vis spectrum. And, the PI films doped-CuPc polymerized by vapor phase deposition have uniformity, fine thermal stability and good nonlinear optical properties, and the third-order optical nonlinear susceptibility χ~((3)) with degenerate four-wave mixing can be 1.984×10~(-9)ESU. 相似文献
5.
In the current study, novel hexagonal rods based on Bi0.4Sb1.6Te3 ingots dispersed with x amount of Se (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) in the form Bi0.4Sb1.6Se3x Te3(1?x) were synthesized via a standard solid-state microwave route. The morphologies of these rods were explored using field-emission scanning electron microscopy (FESEM). The crystal structure of the powders was examined by x-ray diffraction (XRD) analysis, which showed that powders of the 0.0 ≤ x ≤ 0.8 samples could be indexed to the rhombohedral phase, whereas the sample with x = 1.0 had an orthorhombic phase structure. The influence of variations in the Se content on the thermoelectric properties was studied in the temperature range from 300 K to 523 K. Alloying of Se into Bi0.4Sb1.6Te3 effectively caused a decrease in the hole concentration and, thus, a decrease in the electrical conductivity and an increase in the Seebeck coefficient. The maximal power factor measured in the present work was 7.47 mW/mK2 at 373 K for the x = 0.8 sample. 相似文献
6.
Yi Ma Waruna Wijesekara Anders E. C. Palmqvist 《Journal of Electronic Materials》2012,41(6):1138-1146
Thermoelectric thin films of the ternary compounds (Bi x Sb1?x )2Te3 and Bi2(Te1?y Se y )3 were synthesized using potentiostatic electrochemical deposition on gold-coated silicon substrates from aqueous acidic solutions at room temperature. The surface morphology, elemental composition, and crystal structure of the deposited films were studied and correlated with preparation conditions. The thermoelectric properties of (Bi x Sb1?x )2Te3 and Bi2(Te1?y Se y )3 films, i.e., Seebeck coefficient and electrical resistivity, were measured after transferring the films to a nonconductive epoxy support. (Bi x Sb1?x )2Te3 thin films showed p-type semiconductivity, and the highest power factor was obtained for film deposited at a relatively large negative potential with composition close to Bi0.5Sb1.5Te3. In addition, Bi2(Te1?y Se y )3 thin films showed n-type semiconductivity, and the highest power factor was obtained for film deposited at a relatively small negative potential, having composition close to Bi2Te2.7Se0.3. In contrast to Bi2Te2.7Se0.3 thin films, an annealing treatment was required for Bi0.5Sb1.5Te3 thin films to achieve the same magnitude of power factor as Bi2Te2.7Se0.3. Therefore, Bi2Te2.7Se0.3 thin films appear to be good candidates for multilayer preparation using electrochemical deposition, but the morphology of the films must be further improved. 相似文献
7.
Shinji Munetoh Makoto Saisho Takuya Oka Toshiko Osada Hideshi Miura Osamu Furukimi 《Journal of Electronic Materials》2014,43(6):2430-2434
We have synthesized n- and p-type clathrates Ba8?d Au x Si46?x?y with various Au contents (4.6 < x < 6.0) by arc-melting, annealing at 1173 K, and spark plasma sintering at 1073 K. The Au compositions found by wavelength-dispersive x-ray spectrometry for the synthesized samples were slightly lower than the nominal compositions. Ba7.8Au4.6Si41.4 and Ba7.7Au4.9Si41.1 samples showed n- and p-type conduction, respectively. According to the electron count (Ba2+)8Au(3?)5.33Si40.67, the clathrate composition with x = 5.33 is expected to be an intrinsic semiconductor. Our experimental results show that increase of the Au composition causes a transition from n-type to p-type conduction between x = 4.6 and 4.9. We have also calculated the band structures of the Ba8Au x Si46?x clathrate including a vacancy by ab initio calculation based on density functional theory with structure optimization. It was found that the vacancy behaves like an electron acceptor and the numbers of vacancies at 24k sites for the synthesized Ba8Au x Si46?x?y clathrates can be estimated as ~0.4 in a unit cell. 相似文献
8.
《半导体光子学与技术》2010,(4):137-140,145
Structural un-uniformity and electrical anisotropy of μc-Si∶H film are investigated in this paper. It is found that the structure of μc-Si∶H film along the direction perpendicular to the substrate is not uniform, which is modulated by film thickness. In addition, there is a dark conductivity anisotropy along the direction parallel(σ∥) and perpendicular(σ⊥)to the substrate in μc-Si∶H film. The reasons for such an property of μc-Si∶H film and the effect of oxygen contamination are analyzed. 相似文献
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Balancing the contradictory relationship between thermoelectric parameters, such as effective mass and carrier mobility, is a challenge to optimize thermoelectric performance. Herein, the exceptional thermoelectric performance is realized in GeTe through collaboratively optimizing the carrier and phonon transport via stepwise alloying Pb and CuSbSe2. The formation energy of Ge vacancy is efficiently bolstered by alloying Pb, which reduces carrier density and carrier scattering to maintain superior carrier mobility in GeTe. Additionally, CuSbSe2, acting as an n-type dopant, further modulates carrier density and validly equilibrates carrier mobility and effective mass. Accordingly, the promising power factor of 45 µW cm−1 K−2 is achieved at 723 K. Meanwhile, point defects are found to significantly suppress phonons transport to descend lattice thermal conductivity by Pb and CuSbSe2 alloying, which barely impacts the carrier mobility. A combination with superior carrier mobility and lower lattice thermal conductivity, a maximum ZT of 2.2 is attained in Ge0.925Pb0.075Cu0.005Sb0.005TeSe0.01, which corresponds to a 100% promotion compared with that of intrinsic GeTe. This study provides a new indicator for optimizing carrier and phonon transport properties by balancing interrelated thermoelectric parameters. 相似文献
11.
Alloys P. V. Seredin A. V. Glotov A. S. Lenshin I. N. Arsentyev D. A. Vinokurov Tatiana Prutskij Harald Leiste Monica Rinke 《Semiconductors》2014,48(1):21-29
Epitaxial heterostructures produced by MOCVD on the basis of Al x Ga1 ? x As ternary alloys with the composition parameter x ≈ 0.20–0.50 and doped to a high Si and P atomic content are studied. Using the high-resolution X-ray diffraction technique, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy, it is shown that the epitaxial films grown by MOCVD are formed of five-component (Al x Ga1 ? x As1 ? y P y )1 ? z Si z alloys. 相似文献
12.
Anstract Electrical properties (at 80K) of p-n junctions fabricated by ion milling of p-type Hg0.91Mn0.09Te are analyzed. The forward current-voltage characteristics at low biases is shown to be governed by carrier recombination
in the space charge region and at higher biases its voltage dependence is deformed due to the voltage drop across the high-resistance
layer in the diode structure. Under reverse bias, carrier tunneling suppresses other transport mechanisms. At higher reverse
biases, impact ionization by high-energy carriers is responsible for the additional increase in the diode current.
Fiz. Tekh. Poluprovodn. 33, 1438–1442 (December 1999) 相似文献
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Samane Maroufi Rasoul Khayyam Nekouei Sajjad S. Mofarah Anthony P. O'Mullane Yin Yao Sean Lim Claudio Cazorla Veena Sahajwalla 《Advanced functional materials》2021,31(30):2100880
Control over the fabrication of state-of-the-art portable pseudocapacitors with the desired transparency, mechanical flexibility, capacitance, and durability is challenging, but if resolved will have fundamental implications. Here, defect-rich Mn1−x−y(CexLay)O2−δ ultrathin films with controllable thicknesses (5–627 nm) and transmittance (≈29–100%) are fabricated via an electrochemical chronoamperometric deposition using a aqueous precursor derived from end-of-life nickel-metal hydride batteries. Due to percolation impacts on the optoelectronic properties of ultrathin films, a representative Mn1−x−y(CexLay)O2−δ film with 86% transmittance exhibits an outstanding areal capacitance of 3.4 mF cm−2, mainly attributed to the intercalation/de-intercalation of anionic O2− through the atomic tunnels of the stratified Mn1−x−y(CexLay)O2−δ crystallites. Furthermore, the Mn1−x−y(CexLay)O2−δ thin-film device exhibits excellent capacitance retention of ≈90% after 16 000 cycles. Such stability is associated with intervalence charge transfer occurring among interstitial Ce/La cations and Mn oxidation states within the Mn1−x−y(CexLay)O2−δ structure. The energy and power densities of the transparent flexible Mn1−x−y(CexLay)O2−δ full-cell pseudocapacitor device, is measured to be 0.088 μWh cm−2 and 843 µW cm−2, respectively. These values show insignificant changes under vigorous twisting and bending to 45–180° confirming these value-added materials are intriguing alternatives for size-sensitive energy storage devices. 相似文献
15.
Q.L. He Z. Qin J. Zhang F. Gao X. Hu H.Z. Song 《Journal of Electronic Materials》2014,43(5):1432-1435
The influence of Ba doping on the thermoelectric properties of Bi2?x Ba x Sr2 Co2O y (x = 0.00, 0.025, 0.05, 0.075, 0.10, 0.125, and 0.15) samples prepared by the solid-state reaction method was investigated from 333 K to 973 K. For the samples with x ≤ 0.075, the electrical resistivity decreased with increase of the Ba doping amount due to p-type doping and they exhibited metallic electrical conductivity behavior, whereas the samples with x ≥ 0.10 exhibited semiconductor-like electrical conductivity behavior. The Seebeck coefficients of all the samples decreased with increase of the Ba doping amount. The thermal conductivity first decreased for x ≤ 0.075, then increased with higher Ba doping amounts. As an overall result, the dimensionless figure of merit (ZT) of Bi1.925Ba0.075Sr2Co2O y reached the maximum value of 0.245 at 973 K, being 41% higher than that of the undoped sample. 相似文献
16.
Ranita Basu S. Bhattacharya Ranu Bhatt Ajay Singh D. K. Aswal S. K. Gupta 《Journal of Electronic Materials》2013,42(7):2292-2296
Enhancement of the thermoelectric figure of merit is of prime importance for any thermoelectric material. Lead telluride has received attention as a potential thermoelectric material. In this work, the effect of Se substitution has been systematically investigated in PbTe1?x Se x . The thermoelectric properties of synthesized alloys were measured in the temperature range of 300 K to 873 K. For the particular composition of x = 0.5, α was highest at ~292 μV/K, while k was lowest at ~0.75 W/m-K, resulting in the highest dimensionless figure of merit of ZT ≈ 0.95 at 600 K. The increase in thermopower for x = 0.5 can be attributed to the high distortion in the crystal lattice which leads to the formation of defect states. These defect states scatter the majority charge carriers, leading to high thermopower and high electrical resistivity. The dramatic reduction of the thermal conductivity for x = 0.5 can be attributed to phonon scattering by defect states. 相似文献
17.
Sin-Wook You Il-Ho Kim Soon-Mok Choi Won-Seon Seo Sun-Uk Kim 《Journal of Electronic Materials》2013,42(7):1490-1494
Mg2Si1?x Sn x (0 ≤ x ≤ 1) solid solutions have been successfully prepared by mechanical alloying and hot pressing as a solid-state synthesis route. All specimens were identified as phases with antifluorite structure. The electrical conduction changed from n-type to p-type at room temperature for x ≥ 0.5 due to the intrinsic properties of Mg2Sn. The absolute value of the Seebeck coefficient decreased with increasing temperature, and the electrical conductivity increased with increasing temperature; this is indicative of nondegenerate semiconducting behavior. The thermal conductivity was reduced by Mg2Si-Mg2Sn solid solution due to phonon scattering by the alloying effect. 相似文献
18.
Bo Zhang Aimin Chang Qing Zhao Haitao Ye Yiquan Wu 《Journal of Electronic Materials》2014,43(11):4048-4055
The microstructure and thermoelectric properties of Yb-doped Ca0.9?x Yb x La0.1 MnO3 (0 ≤ x ≤ 0.05) ceramics prepared by using the Pechini method derived powders have been investigated. X-ray diffraction analysis has shown that all samples exhibit single phase with orthorhombic perovskite structure. All ceramic samples possess high relative densities, ranging from 97.04% to 98.65%. The Seebeck coefficient is negative, indicating n-type conduction in all samples. The substitution of Yb for Ca leads to a marked decrease in the electrical resistivity, along with a moderate decrease in the absolute value of the Seebeck coefficient. The highest power factor is obtained for the sample with x = 0.05. The electrical conduction in these compounds is due to electrons hopping between Mn3+ and Mn4+, which is enhanced by increasing Yb content. 相似文献
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R. Rajammal V. Anbarasu E. Savarimuthu S. Arumugam 《Journal of Electronic Materials》2014,43(9):3514-3521
The present work is intended to investigate the influence of the gelation state of the sol–gel on the properties of spin-coated cadmium oxide (CdO) thin films. The viscosity of the sol–gel increases at a slow uniform rate up to 5 days (break-off point) after which the rise becomes progressively more rapid and it attains saturation after 10 days of gelation. Films have been grown with gelation times of 2 days, 4 days, 6 days, 8 days, 9 days and 10 days. The visual characteristics of the films have been discussed in terms of the centrifugal force acting on the sol–gel. The sol–gel viscosity seems to be better suited to represent the gelation state of the sol–gel rather than the gelation time. The x-ray diffraction studies show that lower gelation times and lower sol–gel viscosities give rise to single crystalline CdO thin films while gelation times of 6 days and above (i.e. sol–gel viscosities of 2.92 × 10?3 N s m?2 and more) yield polycrystalline CdO thin films. The gelation state of the sol–gel has been found to have a strong bearing on the properties of CdO thin films, and highly conducting and transparent CdO thin films can be achieved by controlling the gelation state of the sol–gel and the results obtained have been reported. 相似文献
20.
Tran Dang Thanh Hoang Thanh Van The-Long Phan Seong-Cho Yu 《Journal of Electronic Materials》2014,43(4):1083-1090
Nanocomposite samples of (1 ? x)La0.7Ca0.3MnO3 + xLa1.5Sr0.5NiO4 (x = 0 to 0.3) were synthesized by a combination of the mechanical milling and solid-state reaction methods. X-ray diffraction analyses and magnetic measurements indicated that no reaction occurred between La0.7Ca0.3MnO3 (LCMO) and La1.5Sr0.5NiO4 (LSNO). The Curie temperature (T C) was almost independent of x, while the metal–insulator transition temperature (T MI) shifted from 251 K for x = 0.0 to 65 K for x = 0.2. The samples with x ≥ 0.25 exhibited insulating behavior in the temperature range from 30 K to 300 K. Addition of LSNO substantially increased the resistivity of the composites. This is attributed to enhanced magnetic disorder at LCMO grain boundaries due to the addition of LSNO. The temperature dependence of the resistivity, ρ(T), could be described by the phenomenological percolation model of phase segregation. Fitting the experimental ρ(T) data in the temperature range of 30 K to 300 K indicated that the activation energy of the composites increases as a function of the LSNO doping concentration (x). 相似文献