共查询到20条相似文献,搜索用时 46 毫秒
1.
Anamika Singh Dimple P. Dutta Mainak Roy A. K. Tyagi M. H. Fulekar 《Journal of Materials Science》2014,49(5):2085-2097
We report an efficient route for the sonochemical synthesis of Bi2?x Sb x WO6 (x = 0, 0.01, 0.02, 0.05, 0.1, and 2) nanorods using bismuth nitrate/antimony chloride and sodium tungstate as precursors. The products obtained have been characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–Vis diffuse reflectance spectroscopy. The photoactivities of all the samples for the Rhodamine-B (RhB) photodegradation were investigated systematically under UV and visible light irradiation. The results of the photocatalytic degradation of RhB in aqueous solution showed that 2–5 % antimony ion doping greatly improved the photocatalytic efficiency of sonochemically synthesized Bi2WO6 nanorods under both UV and visible radiation compared to its undoped counterpart. Among all the samples, the Sb2WO6 nanorods exhibited the highest photodegradation efficiency since 86 % of RhB could be photodegraded in 90 min under UV radiation. The stability of the photocatalysts was ascertained using FT-IR and Raman spectroscopy. 相似文献
2.
N. Gololobow 《Journal of Modern Optics》2013,60(5):387-390
IR-induced elasto(piezo)-optical (PO) triggering effects in complex chalcogenide glasses with general formula Sb2Se3- x Te x ?BaCl2–PbCl2 (with x = 0.2, 0.8, 1.3) were found under the influence of a pulsed 190 ns CO2 laser with wavelength 10.6 μm. It was shown that increasing x leads to an increase of the PO efficiency. This is caused by appearance of enhanced excited dipole moments due to variations of polarizability. Simultaneously variations of the PO versus pump–probe delay times in the nanosecond time range were explored. A substantial role of the electron–phonon subsystem in the observed IR-induced PO triggering is demonstrated. The investigations were done both for diagonal as well as off-diagonal PO tensor components. 相似文献
3.
A superconductor/semimetal/superconductor (S/SM/S) Josephson junction has been developed. We have used an alloy of Pb1–x
Bi
x
(0x 0.6) as the superconductor and Bi as the semimetal. By irradiating at X-band microwave of 10 GHz, Shapiro steps were observed for various bismuth barrier thicknesses inÅ and bismuth weight ratiosx. Finally, we obtained the empirical relationship for barrier thickness, below which microwaves could be detected for various bismuth weight ratiosx at the temperature of 4.2 K. 相似文献
4.
Kinetic studies of crystallization in (Se65Te35)100–x
Sb
x
with 0x10 glasses, using the differential scanning calorimetry technique, were performed. Crystallization enthalpy data, H
c, were collected as a function of composition. The crystallization data were examined in terms of recent analyses developed for non-isothermal crystallization studies, to arrive at E
c. The results indicate bulk nucleation and crystallization with two- and three-dimensional growth, respectively, for the (Se65Te35)98Sb2 and (Se65Te35)92Sb8 glass composition. 相似文献
5.
Y. Sripathi G. B. Reddy L. K. Malhotra 《Journal of Materials Science: Materials in Electronics》1992,3(3):164-167
Bi
x
Se1–x
thin films have been studied because of their structural and optical properties with a view to judging their suitability as the recording medium in phase-change type optical recording. Amorphous films deposited at room temperature were crystallized by thermal annealing. X-ray diffraction analysis and surface morphological studies are reported. A maximum reflectivity difference of 25% at =830 nm was obtained upon amorphous-to-crystalline transition. The optical constants calculated by the Newton-Raphson method using the experimental transmittance, reflectance and thickness data are reported. 相似文献
6.
7.
L. E. Shelimova O. G. Karpinskii V. S. Zemskov P. P. Konstantinov 《Inorganic Materials》2000,36(3):235-242
Analysis of the available crystallographic data shows that the GeTe-Bi2Te3 and GeTe-Sb2Te3 pseudobinary systems contain a wide variety of many-layered, long-period compounds belonging to the nGeTe · mBi2Te3 and nGeTe · mSb2Te3 homologous series. The Hall coefficient, thermoelectric power, and electrical conductivity of some of these compounds were
measured over a wide temperature range. The temperature-dependent carrier mobility data suggest that both acoustic phonons
and point defects contribute to the scattering of charge carriers. The lattice thermal conductivity of the many-layered, long-period
compounds studied, κph = 6–8 mW/(cm K), is notably lower than that of the constituent tellurides 相似文献
8.
W. P. Liu M. T. Li C. T. Lin 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2419-2426
We report the structure, transport, and magnetic properties of K x Fe2?y Se2?z Te z single crystals grown by optical floating zone technique. The phase separation phenomena were observed in the Te-doped samples. With increasing Te doping level, the c-axis lattice parameter expands for both insulating/semiconducting and superconducting phases while the superconducting transition temperature (T c) decreases and eventually vanishes at z = 0.51. The critical current density was estimated to be 103–104 A/cm2 for the all doped samples. The upper critical field and anisotropic superconducting ratio increase with Te doping. We compared the results of critical current density J c, upper critical field μ 0 H c2 and apparent thermally activated energy U 0 for the samples with z = 0, 0.09, and 0.16. The influence of Te doping on the vortex pinning and the implication of U 0 versus μ 0 H is discussed. 相似文献
9.
研究了用低温湿化学法和水热法制备纳米级的Bi2Te3和sb挪e3颗粒,并通过透射电镜观察其微观形貌。Bi2Te3粉末的微观形貌为直径在30-50n之间的片状小颗粒,而sb2Te3颗粒的微观形貌为薄带状,直径约为70nm,长度则为从150-300nm不等,并对其晶体的形核和长大机理进行了讨论。认为,纳米小颗粒状的Bi2Te3晶体可能是通过“表面形核和侧向生长”形成的产物,而薄带状的sb2Te3晶体可能是在Te块解体形成的条带状碎屑基础上形成的。用放电等离子烧结法(spark plasma sintering)制备不同比例的Bi2Te3/Sb2Te3块状复合材料,测量并比较了其热电性能。通过改变Bi2Te3的量,可以提高复合材料的电性能。成分不同的层片间的散射,能更有效地降低块体材料的热导率。在500K的温度下,Bi2Te3和sb2Te3以摩尔比为1:1复合烧结的试样的热导率低达0.7W/(m·K)。进一步优化Bi2Te3和sb2Te3的复合比例,其热电性能可能会有进一步的提高。 相似文献
10.
Joginder Paul Sumit Bhardwaj Kuldeep Kumar Sharma Ravinder Kumar Kotnala Ravi Kumar 《Journal of Materials Science》2014,49(17):6056-6066
We present the structural, dielectric, ferroelectric, magnetic and magnetoelectric studies of lead free; single phase Bi4?x Sm x Ti3?x Co x O12?δ (0 ≤ x ≤ 0.07) ceramics, synthesized using a standard solid-state reaction technique. Raman spectroscopy analysis reveals the relaxation of distortion in TiO6 octahedron. Field emission scanning electron microscopy confirmed the growth of plate-like grains. It is observed that with the substitution of Sm3+ and Co3+ ions the dielectric constant, loss tangent and ferroelectric transition temperature decreases. Electrical dc resistivity, remnant polarization and magnetization increases with increasing Sm3+ and Co3+ contents. The magnetoelectric coupling co-efficient, α = 0.65 mV cm?1 Oe?1 is realized for Bi4?x Sm x Ti3?x Co x O12?δ (x = 0.07) ceramic sample. Our results clearly demonstrate the lead free, multiferroic nature of Sm/Co-substituted Bi4Ti3O12, which may find useful application in designing cost-effective electromagnetic devices. 相似文献
11.
Single crystals of HgTe and Cd
x
Hg1–x
(0.18<x<0.30), oriented for single slip, have been deformed in four-point bending at strain rates 10–4 sec–1 and temperatures from –11 to +84° C for HgTe, and 20 to 195° C for Cd
x
Hg1–x
Te. At the lowest temperatures, the stress-strain curve exhibits a sharp yield relaxation and subsequent zero work hardening regime, as commonly observed for other semiconductors. Experiments show that the yielding mechanism is that proposed by Johnston and Gilman for LiF. Possible explanations for the post-yield zero work hardening phenomenon are discussed. The influence of composition, temperature and strain rate on the stress-strain behaviour are reported. At 20° C, the upper and lower yield stresses (
uy and
1y
) increase with increasingx in qualitative agreement with our earlier hardness results. For Cd0.2Hg0.8Te,
1y
varies with temperature,T, at a strain rate of 10–4 sec–1, according to
1y
exp (Q/kT) whereQ is 0.16 eV. For HgTe the comparable value is 0.11 eV. Atx=0.25 and constant temperature,
1y
depends on strain rate as
1y
1/n
wheren is 4. The stress level for deformation of Cd0.2Hg0.8Te at 10–4 sec–1 and 20° C is 2–3 kg mm–2, comparable with that for InSb at 300° C or Si at 1000° C. Strain rate cycling tests on Cd
x
Hg1–x
Te give values of activation volumeV* around 10b3 at 20° C, independent of plastic strain (up to 2–3%), suggesting that deformation in these alloys is controlled by the Peierls mechanism, as observed in other II–VI compounds. 相似文献
12.
Fang‐Lang Hsu 《中国工程学刊》2013,36(6):755-761
Abstract Vertical Bridgman systems with programmable temperature control are used to grow (SbxBi1:x)2Te3 crystals. High purity Bi, Sb and Te are used as sources and the diameter of 1.1 cm, little soft bulk crystals of (SbxBi1–x)2 Te3 can be obtained. Scanning electron microscope (SEM) and electron probe microanalysis (EPMA) are used to analyze the micro‐structure and the compositions of the crystal. From the X‐ray diffraction patterns it appears that the grown crystal is single crystal or directive polycrystal. If the uniformity of the source solution and grown temperature are under control, then the high quality of single crystals can be obtained. The dependence of crystal structure and the thermoelectric characteristics on the changed compositions of grown crystals are discussed. The optimum composition for the thermoelectric properties is Sb1.00 Bi1.04Te2.96. When the DC current, 3A, is applied to the Sb1.00 Bi1.04 Te2.96 crystal with suitable electrodes, the temperature difference (△T) between two sides of the crystal can be as high as 60°C. It is 2 times larger than that ever obtained by Sb2Te3 crystal. It appeared that the grown (SbxBi1‐x)2Te3 crystals have the potential on the fabrication of thermoelectric devices and electronic cooling system. 相似文献
13.
H. S. Soliman F. M. Allam A. A. El-Shazly 《Journal of Materials Science: Materials in Electronics》1996,7(3):233-239
Seven Cd x Zn(1 ? x Te solid solutions with x = 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 were synthesized by fusing stoichiometric amounts of CdTe and ZnTe constituents in silica tubes. Each composition was used in the preparation of a group of thin films of different thicknesses. Structural investigation of the obtained films indicates they have a polycrystalline structure with predominant diffraction lines corresponding to (111) (220) and (311) reflecting planes, which can be attributed to the characteristics of growth with the (111) plane. The optical constants (the refractive index n, the absorption index k, and the absorption coefficient α) of Cd x Zn(1 \s -x) Te thin films were determined in the spectral range 500–2000 nm. At certain wavelengths it was found that the refractive index, n, increases with increasing molar fraction, x. It was also found that plots of α2 (hv) and α1/2 (hv) yield straight lines, corresponding to direct and indirect allowed transitions respectively obeying the following two equations: $$\begin{gathered} E_g^d = 1.583 + 0.277x + 0.197x^2 \hfill \\ E_g^{ind} = 1.281 + 0.111x + 0.302x^2 \hfill \\ \end{gathered}$$ 相似文献
14.
《Materials Research Bulletin》2004,39(4-5):553-560
The crystal structure of the pyrochlore Bi2−x(CrTa)O7−y has been refined by the Rietveld method from powder neutron and synchrotron X-ray diffraction data. Using the ideal pyrochlore structural model, anomalously high atomic displacement parameters (APD), which could not be satisfactorily explained with anisotropic ADP, of both Bi and O′ sites were observed. The structure was successfully refined with a model that incorporated static displacive disorder of both the Bi and O′ atoms. Using this model physically reasonable ADP parameters for both the Bi and O′ atoms, and improvement in the various measure of fit were obtained. The underbonding of the Bi atoms, observed in ideal pyrochlore model, but removed in the disordered structure, is believed to be the main driving force for this disorder. 相似文献
15.
New multi-component glassy materials with composition of Se78?x Te20Sn2Bi x (0 ≤ x ≤ 6) have been synthesized by well-known melt quenching technique. The as-prepared glasses have been characterized by applying an advanced transient plane source technique to study their thermal transport properties (effective thermal conductivity, diffusivity, specific heat per unit volume) at room temperature. Density measurements have been done to correlate the obtained results. Using the experimental data of density measurements, the basic physical parameters, such as mean atomic volume, compactness, average coordination number etc., are evaluated for the synthesized glasses and the results are discussed as a function of glass composition. We have also determined the phonon mean free path (τ) using the experimental value of effective thermal diffusivity. The composition dependence of the thermal transport properties of aforesaid glassy system has also been discussed. 相似文献
16.
K. Kishio D. Pooke H. J. Trodahl C. K. Subramaniam Y. Kotaka M. Seto S. Kitao Yu. Maeda 《Journal of Superconductivity and Novel Magnetism》1994,7(1):117-121
The electronic state and structural configuration of the intercalated iodine species in stage-1, I-Bi2Sr2Ca n?1Cu n O x (n = l, 2), have been studied through polarization-resolved Raman and129I Mössbauer spectroscopy. The polarization dependence of the Raman spectra and the Mössbauer measurement confirmed the dominant species to be triiodide ions, I 3 ? , with alignment of these linear molecules either along thea- orb-axis in the host crystals. Transport measurements such as thermoelectric power and Hall coefficient clearly indicated that hole carriers are doped into the CuO2 planes upon intercalation, by whichT c of the host superconductor is changed. Furthermore, based on resistivity measurements in a magnetic field, we suggest that the iodine intercalation leads to a decrease of the anisotropy both in normal and superconducting states, suppressing the extremely two-dimensional character of the Bi2Sr2Ca n?1Cu n O x systems. 相似文献
17.
An undoped BiFeO3 thin film, Gd doped Bi0.95Gd0.05FeO3 thin film with a constant composition, Gd up-graded doped Bi1?x Gd x FeO3 and Gd down-graded doped Bi1?x Gd x FeO3 thin films were successfully grown on Pt (111)/Ti/SiO2/Si (100) substrates using a sol-gel and spin coating technique. The crystal structure, ferroelectric and dielectric characteristics as well as the leakage currents of these samples were thoroughly investigated. The XRD (X-Ray Diffraction) patterns indicate that all these thin films consist of solely perovskite phase with polycrystalline structure. No other secondary phases have been detected. Clear polarization-electric field (P-E) hysteresis loops of all these thin films demonstrate that the incorporation of Gd3+ into the Bi site of BFO thin film have enhanced the ferroelectric performance of pure BiFeO3 thin film, and the Gd down-graded doped Bi1?x Gd x FeO3 thin film has the best ferroelectric properties. Compared to other thin films, the optimal ferroelectric behavior of the Gd down-graded doped Bi1?x Gd x FeO3 thin film results from its large dielectric constant, low dissipation factor and low leakage current. 相似文献
18.
Kinetic studies of the glass transition in (Se65Te35)100−x
Sb
x
by differential scanning calorimetry
Calorimetric studies of chalcogenide glasses, (Se65T35)100–x
Sb
x
, obtained by ice-water quenching, were performed by a non-isothermal method. An X-ray diffraction study, as a function of temperature, was carried out, with samples of different compositions. The activation energy for relaxation time, was determined from the heating-rate dependence of values of the glass transition temperature, as a function of x. A maximum in E
t versus antimony concentration occurs at 1–2 at%. 121Sb Mössbauer results confirm the formation of Sb2Se3, by crystallization. 相似文献
19.
A. I. Abou-Aly N. H. Mohammed M. Roumié A. El Khatib R. Awad S. A. Nour El Dein 《Journal of Superconductivity and Novel Magnetism》2009,22(5):495-504
The superconducting phase (Tl0.8 Hg0.2−x
Sb
x
) Ba2Ca2Cu3O9−δ
, with 0.0 ≤x≤0.2, was characterized by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM), proton induced X-ray
emission (PIXE), Rutherford backscattering spectrometry (RBS), electrical resistivity (ρ) and transport critical current density (J
ct). The tetragonal structure of (Tl, Hg)-1223 remains unchanged with antimony-substitution, whereas the lattice parameters
were changed. The actual elemental-content of Tl, Hg, Sb, Ba, Ca and Cu, determined from PIXE, were very close to those of
the nominal elemental-content. The oxygen-stoichiometry of the prepared samples was determined by non-Rutherford backscattering
cross section at 3 MeV H+. A little increase in the oxygen stoichiometry was observed as Sb-content increased. The superconducting transition temperature
T
c, determined from electrical resistivity, increased from 124.8 K to 131.5 K as x increased from 0.0 to 0.1 and then it decreased with the further increase in x. The same behavior is obtained for J
ct vs. x. This indicates that the optimal Sb-substitution in (Tl, Hg)-1223 is at about x=0.1. 相似文献
20.
Thermodynamic properties of Ca1 − x
Er
x
F2 + x
and Ca1 − x
Yb
x
F2 + x
heterovalent solid solutions
N. V. Moiseev P. A. Popov P. P. Fedorov E. A. Garibin V. M. Reiterov 《Inorganic Materials》2013,49(3):325-328
The heat capacity of single crystals of the Ca1 ? x Er x F2 + x (x = 0.05, 0.10) and Ca0.95Yb0.05F2.05 fluorite solid solutions was determined by adiabatic calorimetry in the temperature range 55–300 K. The results were used to obtain temperature dependences of the Debye characteristic temperature, entropy, and enthalpy for the solid solutions. 相似文献