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1.
Wenwei Ge Hong Liu Xiangyong Zhao Xiaobing Li Xiaoming Pan Di Lin Haiqing Xu Xiangping Jiang Haosu Luo 《Applied Physics A: Materials Science & Processing》2009,95(3):761-767
In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal
possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties
were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants
for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (T
m, ε
m) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718),
(305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were
obtained by investigating the piezoelectric constants d
33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d
33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied
during the poling process. The as-grown 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10−11 Ω−1⋅m−1 and 3.95×10−9 Ω−1⋅m−1 at 25°C and 150°C for the 〈001〉 oriented crystal sample. 相似文献
2.
A series of glasses [(TeO2)
x
(B2O3)1−x
]1−y
[Ag2O]
y
with x = 70 and y = 10, 15, 20, 25 and 30 mol% were synthesised by rapid quenching. Longitudinal and shear ultrasonic velocity were measured
at room temperature and at 5 MHz frequency. Elastic properties, Poisson's ratio, microhardness, softening temperature and
Debye temperature have been calculated from the measured density and ultrasonic velocity at room temperature. The experimental
results indicate that the elastic constants depend upon the composition of the glasses and the role of the Ag2O inside the glass network is discussed. Estimated parameters based on Makishima–Mackenzie theory and bond compression model
were calculated in order to analyse the experimental elastic moduli. Comparison between the experimental elastic moduli data
obtained in the study and the calculated theoretically by the mentioned above models has been discussed. 相似文献
3.
A. E. Kar’kin V. V. Shchennikov B. N. Goshchitskii S. E. Danilov V. L. Arbuzov V. A. Kul’bachinskii 《Physics of the Solid State》2003,45(12):2249-2254
The effect of 5-MeV electron irradiation of p-InxBi2?xTe3 single crystals (x=0, 0.04, 0.07), performed at 250 K, on the galvanomagnetic properties of the crystals was studied. The irradiation was shown to change the conduction from the p to the n type. Annealing at temperatures of 310–390 K restores the conduction to the p type. The reversal of the conduction type and variation of the carrier concentration can be accounted for by an increase in the concentration of charged point radiation defects produced in InxBi2?xTe3 by irradiation. Electron irradiation of p-type Te single crystals reduces the electrical resistivity without reversing the conduction type. Annealing restores the original properties almost completely. 相似文献
4.
J. L. Shang T. Zhang H. Wang J. Xie G. J. Hu 《Applied Physics A: Materials Science & Processing》2009,95(3):699-702
Evolution of microstructure and optical property with annealing temperature has been examined for Ba0.9Sr0.1TiO3 films derived from one single precursor solution containing polyethylene glycol polymer. The films sintered below 750°C exhibit
a uniform phase structure across the cross-sections and an ordinary optical thin film feature, while the Ba0.9Sr0.1TiO3 films crystallized at 750°C or higher temperature render a lamellar texture consisting of dense and porous Ba0.9Sr0.1TiO3 layers and a good performance as a one-dimensional photonic crystal. The discrepancy in cross-sectional morphology and reflectance
property observed in these Ba0.9Sr0.1TiO3 films has been preliminarily explained. 相似文献
5.
Temperature dependences of the Faraday effect (FE), which is linear in a magnetic field B; of the nonreciprocal linear birefringence (NB) associated with magnetic field-induced spatial dispersion; and of the Cotton-Mouton effect (CME), which is quadratic in a magnetic field B, have been studied in the transmission region of the γ-Dy2S3 cubic magnetic semiconductor (T d symmetry class) at wavelength λ = 633 nm in the temperature range T = 25–294 K. As the temperature is lowered, the magnitudes of the FE and of the two main NB components, α001 and α011, increase in proportion to the magnetic susceptibility χ. This behavior implies that the magnitude of these effects is determined by the magnetic moment m of the Dy3+ ion induced by the magnetic field B. The CME component \(\beta _{001} (k||[1\bar 10],B||[001])\) grows in proportion to the magnetic susceptibility squared, χ2; i.e., β001 ~ m2. By contrast, the component \(\beta _{111} (k||[1\bar 10],B||[111]))\) exhibits a weaker temperature dependence, which indicates the manifestation of microscopic mechanisms in the CME component β111 that differ from those for β001. 相似文献
6.
P. M. Tarasov V. A. Kulbachinskiĭ V. G. Kytin 《Journal of Experimental and Theoretical Physics》2007,105(1):21-26
Thermoelectric properties of single crystals of a new dilute magnetic semiconductor p-Sb2 ? x Cr x Te3 are studied in the temperature interval 7–300 K. The temperature dependences of the thermal conductivity are measured. The Seebeck coefficient S is found to increase upon doping with Cr. At low temperatures, a ferromagnetic phase with Curie temperature T C ≈ 5.8 K exists for a Cr concentration x = 0.0215, its easy magnetization axis being parallel to the crystallographic axis C 3. At T = 4.2 K, a negative magnetoresistance and anomalous Hall effect are observed; in strong magnetic fields, the Shubnikov-de Haas effect is manifested. 相似文献
7.
L. Pereira A. Morozov M. M. Fraga T. Heindl R. Krücken J. Wieser A. Ulrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(3):325-334
The temperature dependences of the quenching rate constants of the states
N2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}}${\rm C} \ {^{3}{
\rm \Pi }_{u}} v′=0,1) by N2 (X) and of the state
N2 (${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0${\rm C} \ {^{3}{
\rm \Pi }_{u}} \ v^{\prime}=0) by O2 (X) are studied.
Time-resolved light emission from the gas was analyzed in the temperature
range from 300 K to 210 K keeping the gas at constant density. In case of
quenching by N2 (X), the quenching rate constant for the vibrational
level v′= 0 increases by (13 ±3)% with gas cooling whereas the
quenching rate constant for v′= 1 decreases by (5.0 ±2.5)% in this
temperature range. For quenching by O2 (X), the quenching rate constant
decreases by (3 ±2)% with gas cooling. The temperature variation of
the N2 (C 3Πu v′=0) emission intensity for pure nitrogen
and dry air are calculated using the obtained quenching rate constants and
is compared with the experimental data available in the literature. 相似文献
8.
Composite materials used for electrode and electrolyte materials have been intensely studied in view of their advantages such
as higher conductivity and better operational performance compared to their single-phase counterparts. The present work aims
at studying the electrical and structural characteristics of a new composite electrolyte namely, (PbI2)
x
− (Ag2O–Cr2O3)100−x
where x = 5, 10, 15, 20, and 25 mol%, respectively, prepared by the melt quenching technique. The room temperature X-ray diffraction
spectra revealed certain crystalline phases in the samples. AC conductivity analysis for all the prepared samples was carried
out over the frequency range 1 MHz–20 Hz and in the temperature window 297–468 K. The room temperature conductivity values
were calculated to be in the order of 10−5–10−3 Scm−1. An Arrhenius dependence of temperature with conductivity was observed, and the activation energies calculated were found
to be in the range 0.27–0.31 eV. Furthermore, the total ionic transport number (t
i) values obtained for all these indicated the ionic nature of this system.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006. 相似文献
9.
The magneto-transport properties of thick relaxed A-site deficient films
having the composition Pr
Sr0.3MnO3 (P□SMO
with the □ symbol for the Pr vacancy) and Pr0.7Sr
MnO3 (PS□MO) are studied. A
direct comparison with a Pr0.7Sr0.3MnO3 (PSMO)completely relaxed film, deposited under the same growth conditions, shows
a reduction of the in-plane parameter a100 associated to an enhancement
of the out-plane parameter. The strains (bulk strain εB
and biaxial Jahn-Teller strain εJ-T) do vary with the
nature of the cationic vacancy. For example, an enhancement of εB of 9% in the PS□MO film (Sr deficient) produces a decrease
of TC of 30 K, whereas the Pr deficient P□SMO film exhibits a
large reduction of both εB (-16%) and εJ-T (divided by a factor of 5), which enhances TC of 12 K, similarly to previous observations on bulk ceramics. With a reduced
resistivity (ρ<0.02 Ω cm), the obtained Pr-deficient film,
P□SMO, exhibits the best magneto-transport properties with a decreasing
magnetoresistance sensitivity at low field. 相似文献
10.
V. A. Kulbachinskii P. M. Tarasov E. Brück 《Journal of Experimental and Theoretical Physics》2005,101(3):528-534
Magnetic and galvanomagnetic properties of single crystals of a new dilute magnetic semiconductor p-Sb2?xCrxTe3 (x = 0, 0.0115, 0.0215) are investigated in a temperature range of 1.7–300 K. A ferromagnetic phase with a Curie temperature of TC ≈ 5.8 (x = 0.0215) and 2.0 K (x = 0.0115) is detected. The easy magnetization axis is parallel to the C3 crystallographic axis. Analysis of the Shubnikov-de Haas effect observed in these crystals in strong magnetic fields leads to the conclusion that the hole concentration decreases as a result of doping with Cr. Negative magnetoresistance and the anomalous Hall effect are observed in Cr-doped samples at liquid helium temperature. 相似文献
11.
The reflection R(?ω), transmission t(?ω), absorption α(?ω), and refraction n(?ω) spectra of polycrystalline In2O3–SrO samples with low optical transparency, which contain In2O3 and In2SrO4 crystallites with In4SrO6 + δ interlayers, are examined. In the region of small ?ω values, the reflection coefficient decreases as the resistance of samples saturated with oxygen increases. Spectral dependences n(?ω) and α(?ω) are calculated using the classical electrodynamics relations. The results are compared to the data based on the t(?ω) spectra. The calculated absorption spectra are interpreted within the model with an overlap of tails of the density of states in the valence band and in the conduction band. A “negative” gap E gn in the density of states with a width from–0.12 to–0.47 eV is formed in highly disordered samples in this model. It is demonstrated that the high density of defects and the band of deep acceptor states of strontium in the major matrix In2O3 phase are crucial to tailing of the absorption edge and its shift toward lower energies. The direct gap E gd = 1.3 eV corresponding to the In2SrO4 phase is determined. The energy band diagram and the contribution of tunneling, which reduces the threshold energy for interband optical transitions, are discussed. 相似文献
12.
T. I. Milenov V. I. Dimov P. M. Rafailov M. M. Gospodinov 《Applied Physics A: Materials Science & Processing》2008,92(3):643-649
Lattice defects in a scintillation detector made of Bi4Ge3O12 (BGO) could severely impact detector efficiency via non-radiative transfer of electron excitation, thus making thorough investigations
of these defects highly important. Here we present a combined experimental and theoretical study of two- and three-dimensional
defects in a Czochralski-grown BGO crystal. Upon examination by transmission electron microscopy the selected-area electron
diffraction (SAED) patterns in two neighboring parts of the specimen reveal different kinds of two- and three-dimensional
defects. Three sub-grains misoriented at 2.47° with reference to each other and probable presence of stacking faults lying
in {011} planes were observed in the first examined local area. The SAED image taken from an area in the close neighborhood
is much more complicated and is explained in terms of the superposition of reflections from: (i) a partially textured GeO2 second-phase inclusion; (ii) the basic lattice of BGO and (iii) a superlattice-like structure based on the BGO lattice. The
atomic structure of such a superlattice-like structure was theoretically modeled and the corresponding simulated SAED patterns
were found to be in good agreement with the experimentally observed one. 相似文献
13.
The α-Fe2O3/Ag2S p-n heterojunction has been prepared via a facile room temperature successive ionic layer adsorption and reaction (SILAR) method. The heterojunction exhibits higher photoelectrochemical property compared to bare α-Fe2O3. The amount of Ag2S has a significant effect on the PEC performance, which could be controlled by varying the number of SILAR cycles. The α-Fe2O3/Ag2S p-n heterojunction prepared via 6 cycles of SILAR processes displays the best photoelectrochemical performance, which exhibits 1.8 times enhancement of photocurrent density and 70 mV cathodic shift of onset potential compared to bare α-Fe2O3. The improved PEC performance could be attributed to the formation of p-n junction between Ag2S and α-Fe2O3, which not only enhanced the optical absorption ability, but also facilitated the separation efficiency of photogenerated charge carriers and passivized the surface state. 相似文献
14.
K.?Sudheendran M.?Ghanashyam?Krishna K.?C.?James?Raju 《Applied Physics A: Materials Science & Processing》2009,95(2):485-492
Bismuth Zinc niobate (Bi1.5Zn1.0Nb1.5O7) thin films were deposited by pulsed laser deposition (PLD) method on fused silica substrates at different oxygen pressures.
The structural, microwave dielectric and optical properties of these thin films were systematically studied for both the as-deposited
and the annealed films at 600°C. The as-deposited films were all amorphous in nature but crystallized on annealing at 600°C
in air. The surface morphology as studied by atomic force microscopy (AFM) reveals ultra-fine grains in the case of as-deposited
thin films and cluster grain morphology on annealing. The as-deposited films exhibit refractive index in the range of 2.36–2.53
(at a wavelength of 750 nm) with an optical absorption edge value of 3.30–3.52 eV and a maximum dielectric constant of 11
at 12.15 GHz. On annealing the films at 600°C they crystallize to the cubic pyrochlore structure accompanied by an increase
in band gap, refractive index and microwave dielectric constant. 相似文献
15.
A.?V.?Sotnikov R.?Kunze H.?Schmidt M.?Weihnacht M.?Hengst J.?G?tze 《Physics of the Solid State》2009,51(2):275-279
The elastic, piezoelectric, and dielectric constants of new piezoelectric single crystals Sr3NbGa3Si2O14 (SNGS) are measured. The elastic moduli C
11 and C
66 and the piezoelectric coefficient e
11 are determined over a wide temperature range. It is demonstrated that the piezoelectric activity of the crystal is retained
up to the highest temperatures (900°C). 相似文献
16.
Composite cathode material LiFePO4–Li3V2(PO4)3 is synthesized through a chemical reduction and lithiation using FeVO4·xH2O as both iron and vanadium sources. The structural properties of LiFePO4–Li3V2(PO4)3 are investigated. X-ray diffraction results show the composite material containing olivine type LiFePO4 and monoclinic Li3V2(PO4)3 phases. High-resolution transmission electron microscopy and energy-dispersive X-ray spectrometry results indicate that mutual
doping effects take place between the LiFePO4 and Li3V2(PO4)3 particles with V3+ doping the LiFePO4 while Fe2+ dopes the Li3V2(PO4)3. LiFePO4–Li3V2(PO4)3 nanocomposites are formed in the carbon webs. There is no structural compatibility between monoclinic (Li3V2(PO4)3) and olivine (LiFePO4) domains in composite material LiFePO4–Li3V2(PO4)3. 相似文献
17.
N. A. Kalanda G. G. Gorokh M. V. Yarmolich A. A. Lozovenko E. Yu. Kanyukov 《Physics of the Solid State》2016,58(2):351-359
A method has been developed for fabricating nanoporous matrices based on anodic aluminum oxide for the deposition of ferromagnetic nanoparticles in them. The modes of deposition of strontium ferromolybdate thin films prepared by the ion-plasma method have been worked out, and the magnetic and magnetoresistive properties, structure, and composition of the films have been investigated. It has been revealed that the microstructure and properties of the strontium ferromolybdate films deposited by ionplasma sputtering depend on the deposition rate and the temperature of the substrate. Based on the measurement of the electrical resistivity of nanoheterostructures in a magnetic field, it has been found that the magnetoresistance reaches 14% at T = 15 K and B = 8 T, which is due to the manifestation of tunneling magnetoresistance. 相似文献
18.
The optical activity of uniaxial γ1-(GaxIn1?x )2Se3 crystals (x=0.1, 0.2, 0.3, 0.4) is studied at T=295 and 77 K in the spectral range 0.5–0.8 πm. It is found that the cationic substitution In → Ga leads to a nonlinear increase in the specific rotation of the plane of polarization ρ and the component g 33 of the gyration tensor. It is shown that the gyrotropy of the crystals studied is determined by high-energy transitions whose energy exceeds the energy of the edge transitions and that the gyrotropy observed has a molecular origin. 相似文献
19.
A new polyanionic cathode material, Li3V2(PO4)3·LiMn0.33Fe0.67PO4/C for lithium-ion batteries, was synthesized using a sol-gel method and with N,N-dimethyl formamide as a dispersion agent. The analysis of electron transmission spectroscopy and X-ray diffraction revealed that the composite contained two phases. The material has high crystallinity with a grain size of 20–50 nm. The valence states of Mn, V, and Fe in the composite were analyzed by X-ray photoelectron spectroscopy. The electrochemical kinetics in Li3V2(PO4)3 is effectively enhanced by the incorporation of LiMnPO4 and LiFePO4, via structure modification and reduced Li diffusion length. The Li3V2(PO4)3·LiMn0.33Fe0.67PO4/C materials displayed high rate capacity and steady cycle performance with discharge capacity remained 148 mAh g?1 after 50 cycles at the rate of 0.2C. In particular, the composite exhibited excellent reversible capacities, with the values of 157, 134, 120, 102, and 94 mAh g?1 at charge/discharge 0.2, 0.5, 1, 2, and 5C rates, respectively. 相似文献
20.
Composite polymer electrolyte systems composed of poly(methyl methacrylate) (PMMA) as the host polymer, lithium trifluoromethanesulphonate
(also known as lithium triflate; LiCF3SO3) as dopant salt, and a variety of different concentrations of nano-sized fumed silica (SiO2) as inorganic filler were studied. The effect upon addition of SiO2 on the ionic conductivity of the composite polymer electrolytes was investigated, and it was proven that the ionic conductivity
had been enhanced. In addition, the interfacial stability also showed improvement. Maximum conductivity was obtained upon
addition of 2 wt.% SiO2. The complexation of PMMA and LiCF3SO3 was verified through Fourier transform infrared studies. The thermal stability of the polymer electrolytes was also found
to improve after dispersion of inorganic filler. This was proven in the thermogravimetric studies. 相似文献