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1.
Heterophase equilibria in the Ga x In1 − x Bi y As z Sb1 − y − z -InSb and InBi y As z Sb1 − y − z -InSb systems have been analyzed within the simple solution approximation. Ga x In1 − x Bi y As z Sb1 − y − z /InSb and InBi y As z Sb1 − y − z /InSb heterostructures have been grown in a temperature gradient, and their composition and structural perfection have been assessed. 相似文献
2.
Polycrystalline samples La2 – x
Sr
x
CuO4 – (0.06 x 0.5) and La1.85 – x
Sr0.15 + x
Cu1 – x
Co
x
O4 – (0 x 1) were synthesized by a conventional solid state reaction method. The structure, phonon vibration, and conduction were investigated by means of XRD, infrared (IR) spectra, and resistance. It is found that the increase of itinerant hole carriers could mask the in-plane
stretching vibration mode (689 cm–1). The softening of the
phonon vibration mode gives an index of the weakening of
hybridization. The distortion of CuO6 octahedron and the microstructural inhomogeneity induced by Co doping lead to the widening of the IR absorption peaks. 相似文献
3.
S. Yu. Paranchich L. D. Paranchich V. N. Makogonenko M. D. Andriichuk V. R. Romanyuk V. N. Strebezhev Yu. K. Obedzinskii E. V. Shchepetil’nikova 《Inorganic Materials》2010,46(4):349-352
Crystals of the Cd
x
Hg1 − x − y
Cr
y
Se (x = 0.4, y = 0.1) quaternary solid solution have been grown by the Bridgman method, and their microstructure and electrical properties
have been studied. The crystals are shown to contain various types of inclusions in the form of filaments and triangles. 相似文献
4.
W. K. Cheah W. J. Fan K. H. Tan S. F. Yoon D. H. Zhang T. Mei R. Liu A. T. S. Wee 《Journal of Materials Science: Materials in Electronics》2005,16(5):301-307
The GaAs-based double-heterojunction P-i-N structures using InzGa1–zAs1–x–yNxSby as the i-layer is investigated for the first time using solid source molecular beam epitaxy. High quality coherent bulk InGaAsN3.45%Sb (0.5 m) with a lattice-mismatch of 2.6 × 10–3 can be achieved due to the surfactant properties of antimony, while the bulk InGaAsN2% at 0.5 m with 1.06× 10–3 mismatch is fully relaxed. Rapid thermal annealing (RTA) resulted in 25 meV low temperature (LT) photoluminescence (PL) full-width half-maximums (FWHM) for the bulk InGaAsNSb layers. InGaAsNSb experiences 30% less blueshifting with subjected under the same annealing conditions as InGaAsN with similar N content. Room temperature (RT) absorption measurements are in the range of 0.9–1.4 eV. The absorption edge of 1.41 m is achieved for sample D4. 相似文献
5.
S. I. Vecherskii S. N. Tabatchikova B. D. Antonov V. A. Biryukov 《Inorganic Materials》2011,47(12):1356-1360
We have studied the effect of Co and Li concentrations on the phase composition and electrical conductivity of LaCo
x
Fe1 − x
O3 − δ and LaLi0.1Co
x
Fe0.9 − x
O3 − δ perovskite-like oxides synthesized in air at 1470 K. Single-phase materials with an orthorhombic crystal structure were obtained
in the range 0 ≤ x ≤ 0.3. The composition dependences of conductivity have a minimum at x
c = 0.1 and 0.2, respectively. In the range x > 0.1, the conductivity of LaCo
x
Fe1 − x
O3 − δ increases with increasing Co concentration for T > 700 K and decreases for T < 600 K. The conductivity of La(Li0.1Co
x
Fe0.9 − x
)O3 − δ in the range 0 ≤ x ≤ 0.1 and for x ≥ 0.2 increases with Co concentration throughout the temperature range studied. 相似文献
6.
This paper investigates the crystal structure, thermal expansion, and electrical conductivity of two series of perovskites
(LaMn0.25−x
Co0.75−x
Cu2x
O3−δ and LaMn0.75−x
Co0.25−x
Cu2x
O3−δ with x = 0, 0.025, 0.05, 0.1, 0.15, 0.2, and 0.25) in the quasi-ternary system LaMnO3–LaCoO3–“LaCuO3”. The Mn/Co ratio was found to have a stronger influence on these properties than the Cu content. In comparison to the Co-rich
series (LaMn0.25−x
Co0.75−x
Cu2x
O3−δ), the Mn-rich series (LaMn0.75−x
Co0.25−x
Cu2x
O3−δ) showed a much higher Cu solubility. All compositions in this series were single-phase materials after calcination at 1100 °C.
The Co-rich series showed higher thermal expansion coefficients (αmax = 19.6 × 10−6 K−1) and electrical conductivity (σmax = 730 S/cm at 800 °C) than the Mn-rich series (αmax = 10.6 × 10−6 K−1, σmax = 94 S/cm at 800 °C). Irregularities in the thermal expansion curves indicated phase transitions at 150–350 °C for the Mn-rich
series, while partial melting occurred at 980–1000 °C for the Co-rich series with x > 0.15.
I. Arul Raj—on leave from Central Electrochemical Research Institute, Karaikudi, 630006 India. 相似文献
7.
Nithya Ravindran T. Sarkar G. Rangarajan V. Sankaranarayanan 《Journal of Superconductivity》1995,8(5):641-642
We report here the measurements of magnetic susceptibility of Pr2–xCexCuO4–y (x=0, 0.05 and 0.15) from 2K to 300K and the specific heat of Pr1.85Ce0.15CuO4 between 6K and 60K. Fitting of the magnetic susceptibility data to a Curie-Weiss law gave effective magnetic moment (peff) values close to the free ion value of 3.58B for Pr3+. peff was found to decrease with increase in cerium concentration. The site symmetry of Pr3+ in Pr2–xCexCuO4–y (PCCO) host is D4h and a crystal field (CF) Hamiltonian appropriate to tetragonal symmetry was used to analyze the magnetic susceptibility data. J-mixing of all the thirteen multiplets of Pr3+ and intermediate coupled wave functions have been included. A best set of CF parameters obtained not only explains the magnetic susceptibility but also the inelastic neutron scattering spectra (INS) reasonably well. The Schottky component together with Debye and Einstein contributions successfully accounts for the measured specific heat. 相似文献
8.
L. B. Duan X. R. Zhao J. M. Liu W. C. Geng H. N. Sun H. Y. Xie 《Journal of Materials Science: Materials in Electronics》2012,23(5):1016-1021
Al-doped Zn1−x
Mg
x
O and Zn1−y
Cd
y
O thin films were prepared on glass substrates by sol–gel method. The codoping thin films showed preferential c-axis orientation, and the lattice constant c evaluated from the shift of the position of (002) peak displayed an increasing evolution from x = 8 at.% to y = 8 at.%, indicating a roughly statistical substitution of Mg2+ and Cd2+ for Zn2+ in their solid solution. The effects of narrowing and widening band gap (E
g) on conductivity of (Cd, Al) and (Mg, Al) codoped ZnO thin films were simultaneously investigated using transmission spectra
and electrical measurements. The transmittances of these films are obviously decreased by vacuum annealing to 50–60%. However,
the carrier concentration and Hall mobility both increase, and resistivity decreases with narrowing band gap in 1 at.% Al-doped
Zn1−x
Mg
x
O and Zn1−y
Cd
y
O thin films from x = 8 at.% to y = 8 at.%. It is revealed that the conductivity of Al-doped ZnO thin films could be enhanced by this simple band gap modification. 相似文献
9.
F. S. Wang Y. L. Chen C. H. Cheng Y. Zhang Y. Zhao 《Journal of Superconductivity and Novel Magnetism》2010,23(6):1035-1038
La1−x/2Pr1−x/2Ce
x
CuO
y
(LPCCO) samples with doping level up to 20% have been synthesized and their electronic and superconductive properties are
studied. X-ray diffraction revealed that the LPCCO system is a pure phase system with a T’214 structure. Magnetic and resistive
measurements show that the system is superconducting at 0.08≤x<0.20 with T
cmax=25 K at x=0.12. An anti-ferromagnetism transition was also observed in under-doped PLCCO (x=0.05) with the window width of the anti-ferromagnetism phase being significantly narrower than that NCCO and PCCO systems.
The behavior of the Ce doping is compared with Sr doping in this system, and the mechanism is discussed. 相似文献
10.
Grigor L. Georgiev Taslema Sultana Ronald J. Baird Gregory Auner Golam Newaz Rahul Patwa Hans Herfurth 《Journal of Materials Science》2009,44(3):882-888
Kapton? FN and Teflon? FEP (fluorinated ethylene propylene) polymers are resistant to most chemical solvents, heat sealable, and have low moisture
uptake, which make them attractive as packaging materials for electronics and implantable devices. Kapton? FN/Ti and Teflon? FEP/Ti microjoints were fabricated by using focused infrared laser irradiation. Laser-bonded samples were tested with a micro-testing
machine under lap shear load and the bond strength was determined. The bond strength for the Kapton? FN/Ti and Teflon? FEP/Ti systems was found to be 3.32 and 8.48 N/mm2, respectively. The failure mode of the mechanically tested samples was studied by using optical microscopy and scanning electron
microscopy coupled with energy dispersive X-ray spectroscopy. Chemical interactions during laser bonding of Kapton? FN to titanium were studied by using X-ray photoelectron spectroscopy (XPS). The XPS results give evidence for the formation
of Ti–F bonds in the interfacial region. 相似文献
11.
S. T. B. Goennenwein T. Graf T. Wassner M. S. Brandt M. Stutzmann A. Koeder S. Frank W. Schoch A. Waag 《Journal of Superconductivity》2003,16(1):75-78
We report on ferromagnetic resonance measurements of Ga1–x
Mn
x
As thin films with Mn contents 0.022 x 0.051. For x 0.036 and the external magnetic field normal to the thin film, we observe several resonances, which we identify as spin wave resonances. The non-quadratic mode spacing can be consistently explained by a linear gradient in the magnetic properties of the films. From the measurements, the exchange constant A can be deduced for different Mn contents x. 相似文献
12.
S. J. Hao W. T. Jin X. J. Zhang Y. Zhao H. Zhang 《Journal of Superconductivity and Novel Magnetism》2010,23(5):819-822
The co-doped compounds of Y1−x
Ca
x
Ba2Cu3−x
Al
x
O
z
, with x from 0.1 to 0.4, were synthesized through a solid-state reaction method. Structural and superconducting properties have been
investigated by X-ray diffraction, Rietveld refinement, and DC magnetization measurement. The lattice constant a decreases while b increases with the addition of x. The difference between a and b diminishes gradually. Careful study of the crystalline structure shows that the critical temperature (T
c
) changes monotonically with some local structural parameters, such as the difference between Ba and Cu(2) atoms’ Z coordinates,
the bond length of Cu(2)–O(4), and the bond angle of Cu(2)–O(2)–Cu(2), which are all closely related to the interaction between
the perovskite block and the rock salt block in the unit cell. The results indicated that the influence of the crystalline
structure on superconductivity is important and independent of the carrier concentration. 相似文献
13.
R. Awad A. I. Abou-Aly S. A. Mahmoud M. ME. Barakat 《Journal of Superconductivity and Novel Magnetism》2011,24(8):2227-2236
Bulk superconducting samples of type GdBa2Cu3−x
Ru
x
O7−δ
, Gd-123, with x=0.0–0.3 were prepared by the conventional solid-state reaction technique. X-ray powder diffraction (XRD), scanning electron
microscope (SEM), electron dispersive X-ray (EDX) and electrical-resistivity measurements were performed in order to investigate
the effect of Ru4+ ions substitution on Gd-123 phase. Enhancement of both phase formation and the superconducting transition temperature T
c for GdBa2Cu3−x
Ru
x
O7−δ
phase up to x=0.05 was observed from XRD and electrical-resistivity measurement, respectively. This enhancement was confirmed with the
calculated relative volume fraction. For x>0.05, suppression of both phase formation and T
c was obtained and the superconductivity was completely destroyed around x=0.3. The normal-state electrical resistivity was analyzed by the two- and three-dimensional variable range hopping (2D-VRH
and 3D-VRH) and Coulomb gap CG. The results showed that the dominant mechanism was CG for x≤0.075, while was 3D-VRH for x≥0.15. 相似文献
14.
Rajni Sharma R. Ganguly H. Rajagopal A. Sequeira J. V. Yakhmi B. A. Dasannnacharya 《Journal of Superconductivity》1995,8(2):271-277
The results of a systematic powder neutron study on Y1–x
CaxBa2Cu3–y
Co
y
O7± for A (x=y=0), B (x=0;y=0.2), C (x= 0;y=0.4), D (x=y=0.2), and E (x=y=0.4) are investigated with a view to understanding the relation between the structural parameters and superconductivity. Rietveld refinements of the structures show that: (a) Co substitutes at the chain Cu(1) sites only, except for sample E, where the presence of a minor amount of Co at the planar Cu(2) site cannot be ruled out; (b) Co substitution reduced thec-parameter, which is reduced even further upon substitution of Ca at the Y-sites; (c) the occupancy factors of the chain O(1) site indicate an average coordination of 4.8 and 5.1 for Co for samples B and C, but only 4 for D and E; (d) Cu/Co(1) atoms for B and C display large thermal parameters, suggesting a displacement from their ideal centrosymmetric location; (e) the apical Cu(1)-O(4) bond lengthens upon substitution of Co in samples B and C but undergoes shortening upon substitution of Ca in the case of samples D and E. The apical Cu(2)-O(4) bond, on the other hand, shows just the opposite trend; (f) samples D and E show a reduction in the separation of CuO2 layers and their oxygen content; and (e) the bond valence of the Cu(2) ion shows the lowest value of 2.127 for the nonsuperconducting sample C. 相似文献
15.
Guofeng Wang Alejandro Strachan Tahir ?ain William A. Goddard III 《Journal of Computer-Aided Materials Design》2001,8(2-3):117-125
We study the structure and formation energy of kinks in the 1/2a〈111〉 screw dislocations in metallic Tantalum (Ta) using molecular dynamics with a first principles based many-body interatomic
potential. In our study, four a/3〈112〉 kinks are constructed in a quadrupole arrangement in the simulation cell. To the simulation cell, we impose periodic
boundary conditions in the directions perpendicular to the [111] direction and fix boundary condition in the [111] direction.
We find that two, energetically equivalent, core configurations for the 1/2a〈111〈 dislocation lead to 8 distinguishable single kinks and 16 kinds of kink pairs. The different mismatches of the core
configurations along [111] direction attributed to the differences in the formation energy for various types of kinks. Formation
energies for all possible kinds of isolated single kinks and kink pairs have been determined. It was found that 0.730 eV was
the lowest energy cost to form a kink pair in the a/2〈111〉: screw dislocation in Ta.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Yu. G. Selivanov E. G. Chizhevskii V. P. Martovitskiy A. V. Knotko I. I. Zasavitskii 《Inorganic Materials》2010,46(10):1065-1071
Layers and periodic Bragg structures based on Pb1 − x
Eu
x
Te (0 < x < 1) and Pb1 − x
Sn
x
Te (0 < x < 0.1) ternary solid solutions have been grown on (111) BaF2 and (111) Si substrates by molecular beam epitaxy. X-ray diffraction measurements show that the layers in three-period EuTe/Pb0.94Eu0.06Te structures maintain the [111] crystallographic orientation normal to the substrate plane. In the interface plane, the [110]
directions of the layers and substrate are parallel to each other. The full width at half maximum of the rocking curve of
each layer of both the binary and ternary compounds is about 20′. The large optical contrast (40%) in such structures allowed
us to reach 99.9% mid-IR reflectivity. 相似文献
17.
D. D. Polyko L. A. Bashkirov S. V. Trukhanov L. S. Lobanovskii I. M. Sirota 《Inorganic Materials》2011,47(1):75-79
Sr1−x
Pr
x
Fe12 − x
Zn
x
O19 ferrites with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 have been prepared by solid-state reactions between praseodymium, iron, and zinc oxides
and strontium carbonate in air at 1470 K. According to X-ray diffraction results, the samples with x ≤ 0.2 were single-phase and those with 0.3 ≤ x ≤ 0.5 contained, in addition to the magnetoplumbite phase, small amounts of α-Fe2O3, ZnFe2O4, and PrFeO3. The mixed-phase samples further fired twice at 1470 K for 4 and 2 h contained no impurity phases at x = 0.3 and contained only α-Fe2O3 at x = 0.4 and 0.5. In the composition range 0 ≤ x ≤ 0.3, the a and c cell parameters, unit-cell volume V, and X-ray density ρx of the magnetoplumbite phase vary linearly according to the relations a(?) = 5.8869 − 0.0162x, c(?) = 23.027 + 0.449 x, V(?3)= 691.10 + 9.65x, and ρx(g/cm3) = 5.102 + 0.230 x. The highest degree of combined heterovalent substitution of Pr3+ for Sr2+ and Zn2+ for Fe3+ in the SrFe12O19 ferrite (formation of Sr1−x
Pr
x
Fe12 − x
Zn
x
O19 solid solutions) at 1470 K is x = 0.32−0.36. The saturation magnetization per formula unit (n
s) of the x = 0.1 ferrite exceeds that of SrFe12O19 by 1.7% at 6 K and by 15.2% at 308 K. The 308-K n
s and coercive force (σ
H
c) of the x = 0.2 ferrite exceed those of SrFe12O19 by 7.6 and 8.5%, respectively. 相似文献
18.
M. B. Maple C. C. Almasan C. L. Seaman S. H. Han K. Yoshiara M. Buchgeister L. M. Paulius B. W. Lee D. A. Gajewski R. F. Jardim et al. 《Journal of Superconductivity》1994,7(1):97-106
Investigations of Y1–x
M
x
Ba2Cu3O7–
(M=Ce, Th)c-axis oriented thin film specimens show that the rate of depression ofT
c
withx is larger for M=Th, than for M=Ce and Pr, and suggest that Ce, like Th, is tetravalent in this compound. Hall effect measurements on Y1–x
Pr
x
Ba2Cu3O7–
single crystals reveal aT
2 dependence of the cotangent of the Hall angle in the normal state and a negative Hall anomaly belowT
c
in the superconducting state, in agreement with recent reports. Our research shows that the depth, , of the negative Hall signal scales withT/T
c
and that the maximum value of decreases linearly withx and vanishes atx0.24. Magnetoresistance measurements on Y1–x
Pr
x
Ba2Cu3O7–
single crystals indicate that the irreversibility lineH(T
*) obeys a universal scaling relation characterized by anm=3/2 power law nearT
c, with a crossover to a more rapid temperature dependence of belowT/T
c
0.6, similar to that observed for polycrystalline specimens. 相似文献
19.
M. N. Palatnikov O. B. Shcherbina V. V. Efremov N. V. Sidorov A. N. Salak 《Inorganic Materials》2011,47(6):686-689
The microstructure and elastic properties of ceramic samples of high-pressure Li
x
Na1 − x
Ta
y
Nb1 − y
O3 perovskite solid solutions have been studied for the first time in relation to their composition and the synthesis temperature.
The results demonstrate that, with increasing sintering temperature, the Young’s modulus of the Li0.17Na0.83Ta
y
Nb1 − y
O3 solid solutions decreases, which can be understood in terms of the recrystallization behavior of the disordered solid solutions
under high-pressure synthesis conditions. 相似文献
20.
The structural effects of Zn doping and Zn, Co co-doping in Nd1.05Ba1.95Cu3O
z
have been investigated by using neutron diffraction. The Zn atoms are found to occupy exclusively the planar sites in Nd1.05Ba1.95Cu3−x
Zn
x
O
z
samples with x≤0.4. An orthorhombic-to-tetragonal transition behavior was observed in the Nd1.05Ba1.95Cu3−x
Zn
x
O
z
(x=0–0.6) system, while a tetragonal-to-orthorhombic transition was observed in the Nd1.05Ba1.95Cu2.8−x
Zn
x
Co0.2O
z
(x=0–0.6) system as the Zn doping content x increases. A comparative analysis of the structural behavior of Nd1.05Ba1.95Cu3−x
Zn
x
O
z
and Nd1.05Ba1.95Cu2.8−x
Zn
x
Co0.2O
z
(x=0, 0.2, 0.4, 0.6) samples showed that the Co doping can induce an increase in Zn occupancy at the Cu(1) sites as the Zn doping
concentration increases above x=0.4, implying that the distribution of Zn ions between the chain and planar sites can be tuned by the Co substitution for
the chain Cu sites. 相似文献