共查询到20条相似文献,搜索用时 15 毫秒
1.
Kumar Amit Kumari Sapna Kumar V. Kumar Prashant Thakur Vikas N. Kumar Ashok Goyal P. K. Arya Anil Sharma A. L. 《Journal of Materials Science: Materials in Electronics》2022,33(9):6240-6252
Journal of Materials Science: Materials in Electronics - In the present work, lead-free piezoelectric ceramics (Rx)(K0.5Na0.5)(Nb0.96Sb0.04O3)?x(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 [abb. as... 相似文献
2.
G. L. Myronchuk G. E. Davydyuk O. V. Parasyuk O. Y. Khyzhun R. A. Andrievski A. O. Fedorchuk S. P. Danylchuk L. V. Piskach M. Y. Mozolyuk 《Journal of Materials Science: Materials in Electronics》2013,24(9):3555-3563
Novel materials for the infrared two-photon absorption—Tl1?xIn1?xSnxSe2 single crystals (x = 0, 0.1, 0.2, 0.25) were grown. Their optoelectronic properties including two-photon absorption at wavelength equal to 9.4 μm at different temperatures were studied. From the spectral data it was established that band gap energy increases with increasing SnSe2 content in the solid solutions reaching its maximum for the largest content (x = 0.25). The infrared two photon absorption has achieved its maximal value at x = 0.1. The temperature dependence of the optical band gap at various compositions in the range of 77–300 К is practically linear. The band gap value decreases with the increase of T causing the spectral shift of the absorption edge to the low-energy region. Additionally X-ray photoelectron core-level spectra for pristine and Ar+-ion irradiated surfaces of Tl1?xIn1?xSnxSe2 single crystals have been measured. 相似文献
3.
Hiroyuki Sasakura Yoshiya Akagi Shigeki Tsukui Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2008,21(4):249-252
New Pb-based layered cuprates with the 1222 structure have been synthesized in the (Pb0.5B0.5)Sr2 (RE2−x−y
Ce
x
Sr
y
)Cu2O
z
(RE = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y) systems. The almost-single-phase samples in the systems can be obtained
for a nominal composition of x=0.7 and y=0.1. The crystal structure of the samples has a tetragonal symmetry, the lattice parameters of a and c are increasing with increasing the ionic radius of RE element. Despite treatment under high O2 pressure of 100 atm, the samples are semiconductors with the transport process characteristic of three-dimensional variable
range hopping conduction. 相似文献
4.
Rietveld analysis, magnetic, vibrational and impedance properties of (Bi1−xPrx)(Fe1−xZrx)O3 ceramics
Prakash Chandra Sati Manisha Arora Sunil Chauhan Manoj Kumar Sandeep Chhoker 《Journal of Materials Science: Materials in Electronics》2013,24(12):5023-5034
(Bi1?xPrx)(Fe1?xZrx)O3 ceramics with x = 0.03, 0.06 and 0.10 were prepared via solid state reaction route. X-ray diffraction and Raman spectra of the ceramics were recorded for calculating its lattice parameters and structural analysis. Magnetic studies indicated a significant enhancement in magnetization of (Bi1?xPrx)(Fe1?xZrx)O3 ceramics with maximum remnant magnetization of 0.12 emu g?1 for x = 0.06 sample. Fourier transform infrared spectra and Rietveld analysis confirmed the change in bond length arising due to Pr and Zr codoping. Dielectric measurements showed dielectric anomaly around Neel temperature, indicating magnetoelectric coupling in the samples as well as the dielectric relaxation for higher doping. The effect of Pr and Zr codoping on the impedance and modulus behavior of BiFeO3 lattice is discussed. The frequency dependence of electric modulus and impedance of the material show the presence of non-Debye relaxation in the samples. All samples showed energy band gap in the range 2.16–2.0 eV, indicating possibility of optical activity in visible range and making it suitable for photocatalytic applications. 相似文献
5.
The reaction path of the (Ti0.9, Mo0.1)2AlC phase from Ti, Al, TiC and Mo powder mixtures was investigated in detail ranging from 500 to 1450°C, and the results show that the reaction between Ti and Al produced Ti–Al intermetallics, and the reaction between Al and Mo formed Mo–Al intermetallics. And then the (Ti0.9, Mo0.1)2AlC phase was formed by the reaction of Ti–Al, Mo–Al intermetallics, and TiC. At 1350°C for 2?h, a dense (Ti0.9, Mo0.1)2AlC phase with purity was successfully fabricated. The Vickers hardness, flexural strength and fracture toughness were 5.48?GPa, 363.60?MPa and 5.78?MPa m1/2, which were improved by 44, 34 and 136% for (Ti0.80, Mo0.20)2AlC, respectively, compared with the single-phase Ti2AlC. 相似文献
6.
La0.6Sr0.4Co0.2Fe0.8O3?δ–Ce0.8Sm0.2O2?θ–CuO composite cathodes were studied for the potential application in intermediate temperature solid oxide fuel cells. Ce0.8Sm0.2O2?θ electrolyte with porous Ce0.8Sm0.2O2?θ interlayer was successfully prepared by one-step sintering process. The effect of interlayer between cathode and electrolyte and CuO on the electrochemical performance of the composite cathodes was investigated by AC impedance spectroscopy. The application of interlayer decreased the area specific resistance of La0.6Sr0.4Co0.2Fe0.8O3?δ–Ce0.8Sm0.2O2?θ cathode. The addition of CuO to La0.6Sr0.4Co0.2Fe0.8O3?δ reduced the phase formation temperature of La0.6Sr0.4Co0.2Fe0.8O3?δ by 150 °C and the addition of CuO to La0.6Sr0.4Co0.2Fe0.8O3?δ–Ce0.8Sm0.2O2?θ cathode reduced the optimal calcination temperature of the cathode to 800 °C. The composite cathode with 2 mol% CuO calcined at 800 °C exhibited the lowest area specific resistance of 0.05 Ω cm2 at 700 °C in air, which was reduced by 67% compared with that of La0.6Sr0.4Co0.2Fe0.8O3?δ–Ce0.8Sm0.2O2?θ cathode. The studies of the corresponding single cell performance, thermal expansion and thermal cycling behaviors further indicated that the composite cathode with 2 mol% CuO could be a promising cathode material. 相似文献
7.
Two different murdochite-type mixed oxides, (Mg6–x
Li
x
)MnO8 (x = 0, 0.1, 0.2 and 0.3) and (Mg6–x
Al
x
)MnO8 (x = 0, 0.2, 0.4, 0.6) were examined for the catalytic decomposition of N2O in order to make clear the effects of mixed valencies of pairing manganese ions and oxygen vacancies. The valence of manganese ions and the amount of surface oxygen vacancies have been examined with X-ray photoelectron spectroscopy (XPS). (Mg6–x
Li
x
)MnO8 had mixed valence manganese ions and oxygen vacancies on the surface after the substitution. The substituted (Mg6–x
Al
x
)MnO8 had a mixed valence state but oxygen vacancies decresed with x and excess oxygen over stoichiometry was observed at x = 0.4 and 0.6. The reaction rate of N2O decomposition increased after substitution with lithium but hardly increased after the substitution with aluminum in (Mg6–x
A
x
)MnO8. We assumed that the presence of oxygen vacancies on the surface along with pairing altervalent manganese ions affected strongly to enhance the reactivity of N2O decomposition. 相似文献
8.
Dean-Mo Liu 《Journal of Materials Science》1993,28(23):6353-6356
Grain growth in (Ca1–x
,Mg
x
)Zr4(PO4)6 (CMZP) ceramics in the final stage of sintering has been investigated. The grain growth in CMZP ceramics obeys the isothermal grain-growth kinetics with time exponent,n, lying between 1.8 and 2.4 which depends on magnesium content, indicative of a change in grain-growth rate. The time exponent for the grain growth of CMZP can be taken as 2.0 which implies that a normal grain growth develops in the CMZP ceramics. The apparent activation energy for grain growth demonstrates a maximum atx = 0.0 and a minimum atx = 0.1, with 103.2 and 39.4 kcal mol–1, respectively, indicating that a small amount of magnesium promotes grain-boundary migration. The critical grain size for initiating microcracks in the CMZP increases with increasing magnesium and reaches 9–12 m whenx = 0.4. 相似文献
9.
《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
10.
《Materials Research Bulletin》1987,22(2):205-209
Bi5Ti3FeO15 and Bi7Ti3Fe3O21 which are n=4 and n=6 members of the family of oxides of the general formula (Bi2O2)2+(An−1BnO3n+1)2− show unusual superstructures, possibly due to cation ordering. 相似文献
11.
O. Gorur G. Yildirim S. P. Altintas C. Terzioglu 《Journal of Materials Science: Materials in Electronics》2013,24(6):1842-1854
This study deals with the effects of partial Gd3+ substitution for the Cu sites on the electrical, microstructural, physical, mechanical and superconducting properties of YBa2Cu3?xGdxO7?δ ceramic superconductors with x = 0, 0.025, 0.050, 0.100 and 0.150 with the aid of dc resistivity, transport critical current density (J c ), X-Ray analysis (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX), Vickers microhardness (H v ) and density measurements. The samples studied in this work are prepared by the standard solid-state reaction method. The resistivity (at room temperature), critical (onset and offset) temperature, variation of transition temperature, critical current density, hole-carrier concentration, grain size, phase purity, lattice parameter, texturing, surface morphology, element distribution, density, porosity, crystallinity, Vickers microhardness and elastic modulus (E) values of the samples are obtained and compared with each other. The obtained results show that the room temperature resistivity systematically increases with the increment of the Gd content as a result of the hole filling when the onset (T c onset ) and offset (T c offset ) critical temperatures determined from the resistivity curves are found to decrease from 95.2 to 93.6 K and 92.0 to 83.3 K, respectively, showing the presence of impurities and weak links between the superconducting grains. As for the critical current density measurements, the J c values decrease from 132 to 34 A/cm2 as the Gd doping increases. The XRD results give that although the Gd3+ ions substituted tend to occupy both the Cu(1) and Cu(2) sites, the ions are more favorable for the Cu(2) site as a consequence no change of the crystal structure. Besides, the peak intensities belonging to major phase (Y123) decrease monotonously with the increment of the Gd content in the system; however, new peaks belonging to the minor phases start to appear after the doping level of x = 0.0250 beyond which these peaks enhance monotonously, resulting in the decrement of the grain size. Further, the Lotgering indices calculated from the XRD patterns indicate that the texturing of the Y123 grains reduces systematically with the Gd content. According to the SEM investigations, the microstructures of the samples prepared degrade slightly with the content up to the doping level of x = 0.025 after which the morphology suddenly deteriorates due to the appearance of the different phases in the system. EDX measurements show that not only do the elements used for the preparation of the Y123 superconductors with and without Gd content distribute homogeneously but also the level of Cu element rapidly decreases with the increment of the Gd content compared to the other elements, illustrating that the Cu2+ ions may partly be substituted by Gd3+ ions. Moreover, the porosity analyses for the samples depict that the porosity increases with the Gd content, leading to the degradation of the grain connectivity. We also discuss on the mechanical properties of the samples to examine both the elastic modulus and the strength of connection between superconducting grains. 相似文献
12.
S. Gowrishankar L. Balakrishnan T. Balasubramanian N. Gopalakrishnan 《Materials Science and Engineering: B》2013,178(1):31-38
Ga doped ZnO (GZO) and GaP codoped ZnO (GPZO) thin films of different concentrations (1–4 mol%) have been grown on sapphire substrates by RF sputtering for the fabrication of ZnO homojunction. The grown films have been characterized by X-ray diffraction (XRD), photoluminescence (PL), Hall measurement, energy dispersive spectroscopy (EDS), time-of-flight secondary ion mass spectrometer (ToF-SIMS), UV–Vis–NIR spectroscopy and atomic force microscopy (AFM). Unlike in conventional codoping, here we directly doped (codoped) GaP into ZnO to realize p-ZnO. The Hall measurements indicate that 2 and 4% GPZO films exhibit p-conductivity due to the sufficient amount of phosphorous incorporation while all the monodoped GZO films showed n-conductivity as expected. Among the p-ZnO films, 2% GPZO film shows low resistivity (2.17 Ωcm) and high hole concentration (1.8 × 1018 cm?3) by optimum incorporation of phosphorous due to best codoping. Similarly, among the n-type films, 2% GZO shows low resistivity (1.32 Ωcm) and high electron concentration (2.02 × 1019 cm?3) by optimum amount of Ga incorporation. The blue shift and red shift in NBE emission observed from PL acknowledged the formation of n- and p-conduction in monodoped and codoped films, respectively. The neutral acceptor bound exciton recombination (A0X) observed by low temperature PL for 2% GPZO confirms the p-conductivity. Further, the high concentration of P atoms than Ga observed from ToF-SIMS (2% GPZO) also supports the p-conductivity of the films. The fabricated p–n junction with best codoped p-(ZnO)0.98(GaP)0.02 and best monodoped n-Zn0.98Ga0.02O films showed typical rectification behavior of a diode. The diode parameters have also been estimated for the fabricated homojunction. 相似文献
13.
G. T. Huang W. H. Chao J. K. Chang H. D. Liao D. C. Ling F. Z. Chien M. K. Wu 《Journal of Superconductivity and Novel Magnetism》2013,26(3):503-510
Mo2S3 doped with Si, C, B, and Ru, is identified to bear the same crystalline structure P21/m as that of Mo2S3 through XRD analysis. Diamagnetic transitions with χ m ~10?4 emu/g?Oe at temperature ranging from 2 K to 6 K were observed in the doped samples of Si x Mo2S3?x (x=0.1, 0.2, 0.33, 0.5). And both of the x=0.2 and 0.5 samples were found to have double diamagnetic transitions with higher T c at the same temperature of 6.01 K, while Si x Mo2S3?x of x=0.33 displayed an extra ferromagnetic-like response at 63 K. The corresponding transition in resistivity of Si x Mo2S3?x with x=0.1 was noticed to show a mild drop with less than 10 % of its original transition values as measured down to 2 K. But a superconducting-like magnetic field dependence on the phase transition of resistivity was also noted. Its diamagnetic signals were greatly reduced when the applied magnetic fields were raised to 103 Oes. In the doped samples of A0.1Mo2S2.9 (A=C, B, and Ru), the phase transition in resistivity at 4.08 K, 4.62 K, and 4.35 K, respectively, exhibited similar fashion as that in the case of Si0.1Mo2S2.9. 相似文献
14.
Kumar Vipin Rawal Ishpal Kumar Vinod 《Journal of Materials Science: Materials in Electronics》2022,33(2):920-933
Journal of Materials Science: Materials in Electronics - Ultra-violet photodetectors based on p-ZnO/n-Si? heterojunctions have been fabricated by radio-frequency magnetron sputtering... 相似文献
15.
T. Tatsuki A. Tokiwa-Yamamoto T. Tamura X. -J. Wu Y. Moriwaki S. Adachi K. Tanabe 《Journal of Low Temperature Physics》1996,105(5-6):1559-1564
We have recently synthesized new superconducting cuprates containing a mercury-based bilayer, i.e. (Hg,Tl)2Ba2(Ca,Y)Cu2Oy and (Hg1–x Tlx)2Ba2 Can–1 CunOy (x 0.4, n = 3,4) by a high-pressure technique. These compounds are the n=2, 3 and 4 members of a new homologous series, (Hg, Tl)-22(n–1)n. The effects of Tl substitution for Hg on the formation and superconductivity of the (Hg, Tl)-2223 and -2234 phases are investigated. Both the phases are stabilized for the Tl content x of 0.3–0.6. Tc of the as-synthesized (Hg,Tl)-2223 compound increases from 45 K to 81 K with an increase in x. In contrast, Tc of the (Hg,Tl)-2234 compound is almost independent of x (114 K). 相似文献
16.
V. N. Andreev F. A. Chudnovskii 《Journal of Engineering Physics and Thermophysics》1975,28(5):609-613
New types of critical thermistors are proposed, based on V3O5, V4O7, V5O9, and V6O11. It is shown that they can be prepared from Magnelli-phase single crystals, which do not decompose during the phase change. Volt-ampere characteristics and switching voltage-temperature curves were obtained. 相似文献
17.
《Materials Research Bulletin》1987,22(4):467-476
Crystals of BaMnxTiyFe12−(x+y)O19 were grown by spontaneous nucleation in slowly cooled high temperature solutions (HTS method). Bi2O3, BaB2O4, Na2O and NaFeO2 were tested as fluxing salts and the crystallization conditions and the growth results are reported, as a function of different fluxes. Distribution coefficients of elements were deduced from the crystal stoichiometry measured by atomic absorption and microprobe analysis. Crystal structure, lattice parameters, and Curie temperature of crystals were also determined. They were found to be similar to those of polycrystals having the same chemical composition. 相似文献
18.
《Materials Chemistry and Physics》1986,14(5):443-453
The spectral distribution of the photoconductivity in (TlGaSe2)1−x(TlInS2)x single crystals has been studied at 77 K and 300 K. At O ≤ x ≤ 4, Eg is observed to vary linearly with x. Eg(x) deviates from linearity at x = 0.6. This deviation is attributed to the effect of disorder in the composition. Over the range 0.6 to 2.2 eV pronounced impurity photoconductivity is detected at 77 K and 300 K. Deep impurity levels and their neighbourhood in this alloy are established to preserve their positions with the variation in the composition. The analysis of the obtained results indicates that the impurity centres are mainly connected with the cation neighbourhood. 相似文献
19.
《Optical Materials》2014,36(12):2514-2518
Two-photon absorption (TPA) of Tl1−xIn1−xSnxSe2 (x = 0, 0.1, 0.2, 0.25) was studied at CO2 laser wavelength 9.4 μm with pulse duration 1 μs. The studies were performed at different temperatures and for the nanocrystallite sizes varying within the 7–200 nm. The nanocrystals were fabricated by mechanical milling with simultaneous acoustical field treatment and porous filter size separation. The studies have shown that the TPA may be enhanced during the decrease of the nanocrystallite sizes below 50–60 nm. There exists also some critical x value at which the TPA value begin substantially to increase. The comparison with other chalcogenide crystals is performed. The studied nanocrystallites are relatively stable to the infrared laser treatment and are not hygroscopic which allow to use them in different IR optoelectronic devices. 相似文献
20.
A. S. Saidov É. A. Koshchanov A. Sh. Razzakov Sh. K. Ismailov 《Technical Physics Letters》1999,25(12):986-987
Structures comprising Si-Si1−x
Gex-(Ge2)1−x
(InP)x with an intermediate Si1−x
Gex buffer layer were grown on silicon substrates. Morphological examinations, scanning patterns and diffraction spectra, and
also the electrophysical and luminescence properties of the heterostructures were used to show that the crystal perfection
of these structures depends on the choice of liquid-phase epitaxy conditions.
Pis’ma Zh. Tekh. Fiz. 25, 37–40 (December 26, 1999) 相似文献