共查询到20条相似文献,搜索用时 15 毫秒
1.
V. V. Randoshkin N. V. Vasil’eva V. N. Kolobanov V. V. Mikhailin N. N. Petrovnin D. A. Spasskii N. N. Sysoev 《Inorganic Materials》2009,45(4):418-422
Single-crystal gadolinium gallium garnet films have been grown by liquid-phase epitaxy on (111) Gd3Ga5O12 substrates from supercooled Bi2O3-B2O3 fluxed melts at different Gd2O3 concentrations. The luminescence spectra of the films have been measured at 10 and 300 K under unmonochromatized synchrotron X-ray excitation and selective UV synchrotron excitation. The Bi3+ luminescence is discussed. 相似文献
2.
Wen Chiao Chin Kuan Yew Cheong 《Journal of Materials Science: Materials in Electronics》2011,22(12):1816-1826
Samarium oxide (Sm2O3) thin films with thicknesses in the range of 15–30 nm are deposited on n-type silicon (100) substrate via radio frequency
magnetron sputtering. Effects of post-deposition annealing ambient [argon and forming gas (FG) (90% N2 + 10% H2)] and temperatures (500, 600, 700, and 800 °C) on the structural and electrical properties of deposited films are investigated
and reported. X-ray diffraction revealed that all of the annealed samples possessed polycrystalline structure with C-type
cubic phase. Atomic force microscope results indicated root-mean-square surface roughness of the oxide film being annealed
in argon ambient are lower than that of FG annealed samples, but they are comparable at the annealing temperature of 700 °C
(Argon—0.378 nm, FG—0.395 nm). High frequency capacitance–voltage measurements are carried out to determine effective oxide
charge, dielectric constant and semiconductor-oxide interface trap density of the annealed oxide films. Sm2O3 thin films annealed in FG have smaller amount of effective oxide charge and semiconductor-oxide interface trap density than
those oxide films annealed in argon. Current–voltage measurements are conducted to obtain barrier heights of the annealed
oxide films during Fowler–Nordheim tunneling. 相似文献
3.
Choon-Woo Nahm 《Journal of Materials Science》2005,40(23):6307-6309
4.
Semiconducting glasses of the Fe2O3-Bi2O3-K2B4O7 system were prepared by the press-quenching method and their dc conductivity in the temperature range 223–393 K was measured. The glass transition temperature values (Tg) of the present glasses were larger than those of tellurite glasses. This indicates a higher thermal stability of the glass in the present system. The density for these glasses was consistent with the ionic size, atomic weight and amount of different elements in the glasses. Mössbauer results revealed that the relative fraction of Fe increases with increasing Fe2O3 content. Electrical conductivity showed a similar composition dependency as the fraction of Fe. The glasses had conductivities ranging from 10 to 10 Scm at temperatures from 223 to 393 K. Electrical conduction of the glasses was confirmed to be due to non-adiabatic small polaron hopping and the conduction was primarily determined by hopping carrier mobility. 相似文献
5.
Visible-light activities of Gd<Subscript>2</Subscript>O<Subscript>3</Subscript>/BiVO<Subscript>4</Subscript> composite photocatalysts 总被引:1,自引:0,他引:1
Gd2O3/BiVO4 composite photocatalysts were hydrothermal synthesized and characterized by X-ray diffraction, X-ray photoelectron spectroscopy,
scanning electron microscopy, and UV–vis diffusion reflectance spectra; all the composite photocatalysts exhibited enhanced
photocatalytic activities than the pure BiVO4 for degradation of methyl orange under visible-light irradiation. The improved activity of composites was discussed and ascribed
to the electron-scavenging effect of dopants. 相似文献
6.
S. Sailaja S. J. Dhoble Nameeta Brahme B. Sudhakar Reddy 《Journal of Materials Science》2012,47(5):2359-2364
Novel green nanophosphors Ca2Gd2W3O14: Tb3+ were synthesized by solid state reaction method. From the X-ray diffraction profiles it is observed that Tb3+: Ca2Gd2W3O14 phosphors were crystallized in the form of tetragonal structure. The scanning electron microscopy (SEM) image shows that
the particle size is at around 300 nm. In addition to these the prepared powder phosphors were also examined by the energy
dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and mechanoluminescence
(ML) spectra. Emission spectra of Tb3+: Ca2Gd2W3O14 nanophosphors have shown bright green emission at 545 nm (5D4 → 7F5) with an excitation wavelength λexci = 374 nm (7F6 → 5G6). ML spectra shows the radiation effect on the Ca2Gd2W3O14: Tb3+ nanophosphors and from that it was observed that these phosphors are very less sensitive for lower exposure. 相似文献
7.
Gadolinium doped ceria oxide is one of the promising materials as an electrolyte for IT-SOFCs. Ce0·9Gd0·1O1·95 (GDC10) powder was prepared by solid state reaction and sintered at 1473 K, 1573 K, 1673 K and 1773 K. All samples were studied
using X-ray diffraction, scanning electron micrograph and d.c. conductivity measurement. The crystallinity and surface morphology
of the samples improved with sintering temperature. Further, the electrical conductivity measurement indicated that the conduction
mechanism is mainly ionic. The conductivity of samples sintered at 1673 K and 1773 K at 800°C are of the order of 0·1 S-cm−1. The activation energies decreased from 1·25–0·82 eV with increase in sintering temperature. 相似文献
8.
M. A. Borik V. T. Bublik M. A. Vishnyakova A. V. Kulebyakin E. E. Lomonova V. A. Myzina F. O. Milovich V. V. Osiko N. Yu. Tabachkova 《Inorganic Materials》2012,48(2):156-160
The structure of partially stabilized zirconia crystals has been studied by transmission electron microscopy before and after
annealing. Structural characterization of Y2O3-doped (2.8 to 4 mol %) zirconia before annealing showed that all of the samples consisted of twin domains whose size was
dependent on the stabilizer content. Annealing at 2100°C increased the domain size in the composition range 2.8–3.7 mol %
Y2O3 and reduced it at 4 mol % Y2O3. These structural changes allowed us to determine the position of the representative point relative to the phase boundary
in the equilibrium phase diagram of the system. 相似文献
9.
Jianfeng Zhu Guoquan Qi Haibo Yang Fen Wang 《Journal of Materials Science: Materials in Electronics》2011,22(1):96-100
The microstructure and electrical properties of ZnO-Bi2O3-based varistor ceramics doped by Pr6O11 in the content range of 0–5.49 wt% were investigated at different sintering temperatures (1,100, 1,150, 1,175, 1,200 °C).
The increase of sintering temperature leads to more dense ceramics, which increases the nonlinear property, whereas it decreases
the voltage-gradient and leakage current. With increasing Pr6O11 content, the breakdown voltage increases because of the decreases of ZnO grain size. The improvement of non linear coefficient
together with the decrease of leakage current are related to the uniformly distribution of secondary phases along the grain
boundaries of the ZnO. The varistors sintered at 1,175 °C with the 3.37 wt% Pr6O11 doping possess the best electrical properties: the varistor voltage, nonlinear coefficient, and leakage current are 340 V/mm,
46 and 0.63 μA, respectively. 相似文献
10.
R. N. P. Choudhary Dillip K. Pradhan C. M. Tirado G. E. Bonilla R. S. Katiyar 《Journal of Materials Science》2007,42(17):7423-7432
The nanocrystalline fine powders (∼80 nm) of (Ba1−x
La
x
)(Fe2/3W1/3)1−x/4O3, (BLFW) (x = 0.0, 0.05, 0.10 and 0.15) were synthesized with a combined mechanical activation and conventional high-temperature solid-state
reaction methods. Preliminary X-ray structural analysis of pellet samples (prepared from fine powders) showed formation of
a single-phase tetragonal system. Detailed studies of dielectric properties (εr and tan δ) exhibit that these parameters are strongly dependent on frequency, temperature and La composition. The La-substitution
increases the dielectric constant and decreases the tan δ up to 10% substitutions of La at the Ba-site, and then reversed
the variation, and hence this composition is considered as a critical composition. This observation was found valid for structure,
microstructures, dielectric constant, electrical conductivity, J–E characteristics and impedance parameters also. Like in other perovskites (PZT, BZT), La substitution plays an important role
in tailoring the properties of Ba(Fe2/3W1/3)O3 ceramics. 相似文献
11.
Effects of Y2O3 contents on the microstructure and electrical properties of Pr6O11-based ZnO varistor have been studied. The varistor voltage (V1mA) and the nonlinear exponent () increased with increasing Y2O3 contents, whereas the dielectric constant decreased. Y-rich phase segregated at nodal points in grain boundaries. The average grain size decreased with increasing Y2O3 content. The specimen with 4.0 mol% Y2O3 sintered at 1285 C exhibited the highest nonlinear exponent ( = 77) with the dielectric constant, ~352 at 1 kHz. 相似文献
12.
Deepa Singh Vandana Gupta Ranjan K. Singh K. K. Bamzai 《Journal of Materials Science: Materials in Electronics》2017,28(12):8414-8422
Neodymium doped gadolinium manganate with general composition (Nd0.1Gd0.9Mn2O5) was prepared by co-precipitation method. Microstructural and compositional analysis has been carried out by X-ray diffraction and scanning electron microscopy. The optical studies have been carried out by Raman and FTIR. The electrical properties studied include dielectric constant, dielectric loss, ac conductivity and activation energy in the temperature range 20–400 ?°C. The shift in the dielectric peak towards higher temperature side with increasing frequency indicates frequency dispersion and suggesting the relaxational behaviour of the material. Frequency dependence of ac conductivity obeys the universal power law. The value of activation energy depends on increase in frequency. The room temperature magnetic behaviour has been analyzed from the magnetic field dependent magnetization curve. The grown material exhibits the paramagnetic behavior at room temperature. 相似文献
13.
L. T. Denisova L. A. Irtyugo Yu. F. Kargin V. V. Beletskii V. M. Denisov 《Inorganic Materials》2016,52(6):584-586
Gd2Sn2O7 gadolinium stannate with the pyrochlore structure has been prepared by solid-state reaction and its high-temperature heat capacity has been determined by differential scanning calorimetry in the temperature range 350–1020 K. The Cp(T) data are shown to be well represented by the classic Maier–Kelley equation. The experimental Cp(T) data have been used to evaluate the thermodynamic functions of gadolinium stannate: enthalpy increment H°(T)–H°(339 K), entropy change S°(T)–S°(339 K), and reduced Gibbs energy Ф°(Т). 相似文献
14.
Monophasic CaNaBi2Nb3O12 powders were synthesized via the conventional solid-state reaction route. Rietveld refinement of the X-ray powder diffraction
(XRD) data and selected area electron diffraction (SAED) studies confirmed the phase to be a three-layer Aurivillius oxide
associated with an orthorhombic B2cb space group. The dielectric properties of the ceramics have been studied in the 300–800 K temperature range at various frequencies
(1 kHz to 1 MHz). A dielectric anomaly was observed at 676 K for all the frequencies corresponding to the ferroelectric to
paraelectric phase transition as it was also corroborated by the high temperature X-ray diffraction studies. The incidence
of the polarization–electric field (P vs. E) hysteresis loop demonstrated CaNaBi2Nb3O12 to be ferroelectric. 相似文献
15.
We gave studied the crystallization behavior of 30BaO · 25Bi2O3 · 45B2O3 glasses doped with Eu2O3 to different levels. At a Eu2O3 content of 7 mol % or higher, the glasses undergo volume crystallization. The only precipitating phase is a solid solution
between europium and bismuth oxides. With increasing europium concentration in the glass, the structure of the crystallites
changes from cubic to rhombohedral. We have investigated the morphology, physicochemical properties, and luminescence spectra
of the glasses and glass-ceramics. 相似文献
16.
A. Di Loreto A. Frattini R. Machado M. G. Stachiotti 《Journal of Materials Science: Materials in Electronics》2018,29(23):19783-19790
The effects of the replacement of Ba2+ by off-center Mg2+ ions on the structural and electrical properties of BaZr0.1Ti0.9O3 ceramics were investigated. We show that the use of magnesium as A-site dopant favors the formation of the perovskite phase at a lower temperature and improves the densification of the ceramics. Combining XRD, SEM and electrical measurements, we determined that the solubility limit of Mg is ~ 2%. We show that Mg doping leads to a decrease in both the Curie temperature and remnant polarization of the ceramics. A 1% Mg content, however, enhances the room-temperature d33 piezoelectric coefficient due to the composition proximity to an impurity induced morphotropic phase boundary. 相似文献
17.
The microstructure, electrical properties, and stability of the varistor ceramics, which are composed of ZnO-Pr6O11-CoO-Cr2O3-La2O3 (ZPCCL)-based ceramics, were investigated for various La2O3 contents. The increase of La2O3 content led to more densified ceramics, whereas abruptly decreased the nonlinear properties by incorporating beyond 1.0 mol%. The highest nonlinearity was obtained from 0.5 mol% La2O3, in which the nonlinear exponent is 81.6 and the leakage current is 0.1 μA. As the La2O3 content increases, the donor concentration and density of interface states were increased from 0.64×1018 to 16.89×1018/cm3 and from 2.21×1012 to 5.16×1012/cm2, respectively. However, the barrier height greatly decreased with increasing La2O3 content, reaching a maximum (1.47 eV) for 0.5 mol% La2O3. 相似文献
18.
New solid solutions, Bi2?x?y Tm x Nb y O3+δ, with tetragonal and cubic structures have been synthesized in the Bi2O3-Tm2O3-Nb2O5 system, and their electrical conductivity has been measured at temperatures from 670 to 1020 K. The 1020-K conductivity of the tetragonal solid solution Bi1.8Tm0.15Nb0.05O3+δ is comparable to that of Bi1.75Tm0.25O3, the best conductor in the Bi2O3-Tm2O3 system. 相似文献
19.
I. I. Lebedeva I. P. Sizeneva Yu. G. Tselishchev D. M. Kisel’kov V. A. Val’tsifer 《Inorganic Materials》2016,52(10):1002-1009
We have studied the effect of the hydrothermal synthesis temperature on Al2O3 structure formation and examined the role of the phase composition of the precursor gel and surfactant in the formation of the pore structure of Al2O3. A technique has been proposed for the synthesis of TiO2/Al2O3 binary xerogels, and the effect of TiO2 content on the pore structure parameters and adsorption properties of TiO2/Al2O3 has been investigated. 相似文献
20.
Platelike Li1 ? x Na x Cu2O2 single crystals up to 2 × 10 × 10 mm in dimensions have been grown by slowly cooling (1 ? x)Li2CO3·xNa2O2·4CuO melts in alundum crucibles in air. Li1 ? x Na x Cu2O2 solid solutions in the LiCu2O2-NaCu2O2 system have been shown to exist in the composition range 0.78 < x < 1. The temperature stability ranges of NaCu2O2 and LiCu2O2 are 780–930 and 890–1050°C, respectively. The Mössbauer spectra and electrical conductivity of the crystals have been measured. 相似文献