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1.
The reversible photoinduced change exhibited by amorphous chalcogenide glasses has been extensively studied recently, partly as an interesting subject for fundamental research in the field of disordered solids and partly due to potential applications in optoelectronics such as photoresists, optical memories, optoelectronic circuits, etc. The illumination of many amorphous chalcogenides changes their internal and/or surface structure while preserving their amorphous state. In this study, amorphous arsenic trisulfide (As2S3) thin film samples whose thickness is 5 µm were prepared on silicon wafers by thermal evaporation, and their thermal diffusivity and thermal conductivity were measured by photoacoustic spectroscopy and a 3? method, respectively. These measurements were repeated after illumination by an Ar+ laser beam whose photon energy E g is consistent with the energy band gap of As2S3. The results show that the thermal diffusivity and thermal conductivity increase by about 50% and 14–15%, respectively, by the photoinduced darkening, and this can be explained by the rearrangement of atoms and thermal expansion of the film. 相似文献
2.
R. B. Onyancha J. Shimoyama J. Das K. Hayashi H. Ogino V. V. Srinivasu 《Journal of Superconductivity and Novel Magnetism》2017,30(9):2429-2434
‘Non-resonant Microwave Absorption’ (NRMA) or the ‘Low field microwave absorption’ (LFMA) measurements on high-quality polycrystalline SmFeAsO0.80F0.20 superconducting sample were carried as functions of temperature and microwave power. The LFMA line shape is complex with two peaks namely; broad peak 1 and narrow peak 2 akin to one reported in SmFeAsO0.88F0.12 as reported by Onyancha et al (Supercond. Nov. Magn. 28, 2927–2934, 2015). This unquestionably illustrates that these peaks are a common feature in F-doped SmFeAsO. The LFMA signal as a function of temperature reveals that T c ? T ? = 1K in SmFeAsO0.80F0.20 compared to 4 K in SmFeAsO0.88F0.12 (T ? is the characteristic temperature at which the narrow peak appears as we cool down the sample below T c); hence inferring that the narrow peak is fluorine doping dependent. Furthermore, LFMA signal evolution with microwave power does not show phase reversal (anomalous absorption) at 2.227 mW which is a stark contrast to what was observed in SmFeAsO0.88F0.12 as reported by Onyancha et al (Physica C: Supercond. Appl. 533:49–52, 2017). The absence of phase reversal within measured microwave power indicates presence of hysteretic Josephson junction. These findings establish few non-superconducting inclusions in SmFeAsO0.80F0.20 system. 相似文献
3.
A new type of novel orange-red emitting Eu-doped ZnO/TiO 2 nanocomposite phosphors have been synthesized by simple low temperature co-precipitation route. Structure and morphology of the prepared sample have been investigated using X-ray diffraction and field emission scanning electron microscopy (FESEM) techniques. XRD pattern confirmed the presence of both phases of ZnO and TiO 2 simultaneously. The luminescence properties, such as photoluminescence (PL) excitation and emission spectra, Judd–Ofelt parameters, CIE colour coordinates and the dependence of luminescence intensity on the doping level were investigated. The luminescence spectrum characteristics of Eu 3+ ions have a strong dependence on Eu 3+ doping levels as well as ZnO/TiO 2 ratio variations. The photoluminescence results indicate that these phosphors could be efficiently excited by near-ultraviolet radiation, which causes emissions in orange–red regions. 相似文献
4.
Tantalum oxide (Ta
2
O
5
) films and Al/Ta
2
O
5
/Si MOS capacitors were prepared at various powers by ultraviolet photo-inducing hot filament chemical vapour deposition (HFCVD).
Effects of ultraviolet light powers on the structure and electrical properties of Ta
2
O
5
thin films were studied using X-ray diffraction (XRD) and atomic force microscopy (AFM). The dielectric constant, leakage
current density and breakdown electric field of the samples were studied by the capacitance–voltage (C–V) and current–voltage
(I–V) measurements of the Al/Ta
2
O
5
/Si MOS capacitors. Results show that the Ta
2
O
5
thin films grown without inducement of UV light belong to amorphous phase, whereas the samples grown with inducement of UV-light
belong to δ-Ta
2
O
5
phase. The dielectric constant and leakage current density of the Ta
2
O
5
thin films increase with increasing powers of the UV- lamps. Effects of UV- lamp powers on the structural and electrical
properties were discussed. 相似文献
5.
In the present investigation, we report chemical synthesis of hydrous tin oxide (SnO
2
:H
2
O) thin films by successive ionic layer adsorption and reaction (SILAR) method at room temperature (
\thicksim \thicksim 300 K). The films are characterized for their structural and surface morphological properties. The formation of nanocrystalline
SnO
2
with porous and agglomerated particle morphology is revealed from X-ray diffraction (XRD) and scanning electron microscopy
(SEM) studies, respectively. The Fourier transform infrared spectroscopy (FTIR) study confirmed the formation of Sn–O phase
and hydrous nature of the deposited film. Static water contact angle studies showed the hydrophilic nature of SnO
2
:H
2
O thin film. Electrical resistivity showed the semiconducting behaviour with room temperature electrical resistivity of 10
5
W\boldsymbol\Omega cm. The electrochemical properties studied in 0·5 M Na
2
SO
4
electrolyte showed a specific capacitance of 25 F g
− 1
at 5 mVs
− 1
scan rate. 相似文献
6.
Double perovskite polycrystalline single phase and dense Sr
2
SbMnO
6
(SSM) ceramics, fabricated using the nanocrystalline powders synthesized by molten salt method, exhibited high dielectric
constant with low dielectric loss as compared to that of SSM ceramics obtained from the powders prepared by solid-state synthesis
method. The dielectric data obtained over a wide frequency (100 Hz–1 MHz) and temperature (190 K–300 K) ranges exhibited distinct
relaxations owing to both the grain and grain boundary. The dielectric dispersion was modeled using the Cole–Cole equation
consisting of two separate relaxation terms corresponding to the grain and grain boundary. The grain and grain boundary relaxations
observed in the Nyquist plots (Z
′ and Z
″) were modeled by an equivalent circuit consisting of two parallel RC circuits connected in series with each other. A careful
analysis of both the impedance (Z
″ vs ω) and modulus (M
″ vs ω) behaviour corroborated the conclusions drawn from the dielectric data. 相似文献
7.
Qianjin Wang Qiuhong Tan Yingkai Liu 《Journal of Superconductivity and Novel Magnetism》2018,31(8):2437-2441
The magnetism of undoped and Mn-doped In2O3 has been investigated by employing density functional calculations. For undoped In2O3, a neutral In vacancy in In2O3 leads to the formation of a net moment of 3 μ B, which originates from the strong spin polarization of 2p orbitals of O atoms. While, Mn-doped In2O3 system shows robust ferromagnetism which can be attributed to the p-d hybridization between Mn and their neighboring O atoms. In addition, because two O atoms between the two Mn atoms are removed, the ground state of the system have a transformation from the ferromagnetic to the antiferromagnetic state, which further demonstrates that the ferromagnetism is mediated through the p-d interaction. 相似文献
8.
This paper reports the results of photoacoustic measurements of Cd1-xBexSe mixed crystals grown by the high pressure Bridgman method with varying concentrations of Be (0.1 < x < 0.2). For examining continuous wave photoacoustic spectra, a piezoelectric transducer (PZT) and an open cell were used. An increase of the energy gap with increasing x has been observed. The thermal diffusivity values were estimated using the dependence of the amplitude and phase of the PA signal on the light modulation frequency.Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A. 相似文献
9.
Sanjeev K. Srivastava Alireza Aghajamali 《Journal of Superconductivity and Novel Magnetism》2016,29(6):1423-1431
In this paper, we present the theoretical investigation and study of reflectance properties in a 1D ternary annular photonic crystal (TAPC) containing a semiconductor and a high-temperature superconductor. The proposed structure consists of alternate layers of indium nitride (InN), Bi2Sr2CaCu3O8 (BSCCO), and air placed in free space. A reflectance spectrum of the TAPC is obtained by employing the transfer matrix method (TMM) in the cylindrical waves for both transverse electric (TE) and transverse magnetic (TM) polarized waves. From the study of reflectance spectra, it is observed that the reflection band of the annular photonic crystal depends on the azimuthal mode number m in addition to other parameters. It is found that for azimuthal mode number m = 0, the width of the reflection band of the annular photonic crystal is the same as that of a planar photonic crystal (PPC). When the azimuthal mode number increases, the width of the reflection band increases at higher m values (m >5) for TE waves. In the case of the TM wave, it is interesting to observe that a superpolariton gap is created for a higher value of the azimuthal number (m >0). Further, we see the effect of the starting radius (ρ 0) on the reflection band of the TAPC structure at the given m number for both TE- and TM-polarized waves. Finally, the effect of temperature on the reflectance spectra for both TE and TM waves at the given ρ 0 and azimuthal mode has been studied. 相似文献
10.
Remarkable feature of the phase diagram of sulfur hydrides, the record-high T c superconductors, is a sharp increase near P ≈ 150 GPa from T c ≈ 120 to ≈ 200 K. This increase is a signature of the structural transition. The present study is concerned with the nature of this phase transition. One can demonstrate that the symmetry analysis along with an analysis of the impact of lattice deformations lead to the conclusion that we are dealing with the first-order transition. Such a transition is manifested in an abrupt appearance of small pockets on the Fermi surface and, correspondingly, the two-gap energy spectrum. 相似文献
11.
Harrison’s first principle pseudopotential (HFPP) technique in conjunction with BCS theory and McMillan’s formalism has been
used for the investigation of superconducting state parameters viz., Coulomb pseudopotential μ
∗, electron–phonon coupling strength λ, SC transition temperature T
C
, interaction strength N
0
V, semi band gap Δ, energy or mass renormalization parameter Z
0 and isotope effect exponent δ. The ground state properties of MgB2 have also been calculated employing full-potential linearized augmented plane wave (FLAPW) method. This enables us to estimate
the equilibrium values of bulk modulus and its pressure derivative through optimization of the crystal structure of the system.
We have also described the total density of state (DOS) and the partial DOS (PDOS) around the Fermi energy. 相似文献
12.
A. K. Vershovskii 《Technical Physics Letters》2011,37(2):140-143
The possibility of creating a new scheme of a laser-pumped quantum magnetometric device based on a double-beam M
X
magnetometer is considered. The proposed system ensures the simultaneous measurement of the modulus of the Earth’s magnetic
field vector (with an absolute accuracy of 0.02 nT) and two angles of deviation of this vector with an absolute accuracy and
sensitivity of not worse than 0.4″ (0.1 nT) at a measurement time of τ = 1 s. In contrast to the known analogous systems,
the proposed scheme does not require generating additional magnetic fields. 相似文献
13.
V. S. Sulyaeva V. A. Shestakov Yu. M. Rumyantsev M. L. Kosinova 《Inorganic Materials》2018,54(2):133-139
Using mechanochemical synthesis, we have prepared zirconium borohydride, Zr(BH4)4, as a precursor for ZrB2 film growth by chemical vapor deposition. We have carried out the thermodynamic modeling of phase formation processes in the Zr–B–(N)–H and Zr–B–(N)–H–O systems in a wide temperature range, from 100 to 2500°C, at various p(H2)/p(Zr(BH4)4) and p(NH3)/p(Zr(BH4)4) partial pressure ratios in the starting gas mixtures. A process has been proposed for the growth of zirconium diboride films by Zr(BH4)4 decomposition using two techniques: chemical vapor deposition and plasma-enhanced chemical vapor deposition. We also developed a process for the growth of multilayer ZrB2-and BC x N y -based structures. 相似文献
14.
R. Velazquez-Hernandez I. Rojas-Rodriguez J. Carmona-Rodríguez S. Jiménez-Sandoval M. E. Rodriguez-Garcia 《International Journal of Thermophysics》2011,32(3):720-728
In this research quaternary alloy thin films made of Cu, CdTe, and O have been grown and characterized. The samples used in
this investigation were grown simultaneously by reactive RF co-sputtering and by introducing oxygen and argon in the chamber
during growth and changing the power in the Cu target from 10 W to 50 W. The carrier distribution as a function of the position
was studied by using energy dispersive spectroscopy–scanning electronic microscopy (EDS–SEM), micro-Raman spectroscopy, and
photocarrier images. Structural characterization was carried out by using X-ray diffraction. According to the results, a lateral
carrier distribution was found in all samples and a new phase identified as Cu2Te was revealed for samples grown at 50 W. 相似文献
15.
The time-dependent Ginzburg–Landau equation with thermal noise is used to calculate the Nernst signal e
N
, describing the Nernst effect, in type-II superconductor in the vortex-liquid regime. The Gaussian method used is an elaboration
of the Hartree–Fock method. An additional assumption often made in analytical calculations that only the lowest Landau level
significantly contributes to physical quantities of interest in the high-field limit is lifted by including all the Landau
levels. The values of e
N
are in good quantitative agreement with experimental data for temperature close to T
c
on Bi2Sr2CaCu2O8+δ
and Bi2Sr2Ca2Cu3O10+δ
. 相似文献
16.
K. A. Vanaja Umananda M. Bhatta R. S. Ajimsha S. Jayalekshmi M. K. Jayaraj 《Bulletin of Materials Science》2008,31(5):753-758
P-type transparent semiconducting AgCoO2 thin films were deposited by rf magnetron sputtering of sintered AgCoO2 target. The AgCoO2 films grown by rf sputtering were highly c-axis oriented showing only (001) reflections in the X-ray diffraction pattern unlike in the case of amorphous films grown
by pulsed laser deposition (PLD). The bulk powder of AgCoO2 was synthesized by hydrothermal process. The optical bandgap was estimated as 4·15 eV and has a transmission of about 50%
in the visible region. The temperature dependence of conductivity shows a semiconducting behaviour. The positive sign of Seebeck
coefficient (+220 μVK−1) indicates p-type conductivity. Transparent p-n heterojunction on glass substrate was fabricated by rf magnetron sputtering of p-AgCoO2 and n-type ZnO: Al thin films. The structure of the diode was glass/ITO/n-ZnO/p-AgCoO2. The junction between p-AgCoO2 and n-ZnO was found to be rectifying. 相似文献
17.
A. N. Golubenko M. L. Kosinova V. S. Sulyaeva Yu. M. Rumyantsev N. I. Fainer F. A. Kuznetsov 《Inorganic Materials》2009,45(12):1342-1345
Thermodynamic modeling of the chemical vapor deposition of boron-carbonitride-based films in the B-C-N-H-O system using mixtures of N-trimethylborazine and nitrogen is carried out for reduced pressures (13.3 and 1.33 Pa) and a wide temperature range (300–1300 K). The source of oxygen impurities in this system is a residual pressure of 0.40 Pa. The results indicate that films of various compositions can be grown. The conditions for the deposition of BC x N y films are identified. 相似文献
18.
M. Pawlak F. Firszt S. Łęgowski H. Męczyńska J. Gibkes J. Pelzl 《International Journal of Thermophysics》2010,31(1):187-198
The concentration dependence of the thermal conductivity and thermal diffusivity were determined for Cd1-x
Mg
x
Se mixed crystals in the temperature range between 20 ◦C and 40 ◦C. To determine the thermal transport properties, the photopyroelectric setup in the back detection configuration was constructed.
In the concentration range 0< x <0.36, both thermal conductivity and thermal diffusivity were found to decrease with increasing magnesium concentration as
well as with increasing temperature. The observed concentration dependence is discussed in the framework of the Adachi model. 相似文献
19.
n-Si/n-Cd1 - x
ZnxS heterojunctions are produced by electrodepositing Cd1 - x
ZnxS (0 x 0.6) films on silicon substrates, and their electrical and photoelectric properties are studied. The results demonstrate that the spectral response of the heterojunctions depends strongly on the film composition and heat-treatment conditions. The highest photosensitivity is achieved at x = 0.6 by heat treatment at 350°C for 7 min: V
OC = 0.5 V and I
SC = 3.8 mA/cm2 under illumination of 1500 lx at 300 K.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 276–280.Original Russian Text Copyright © 2005 by Mamedov, Gasanov, Amirova.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date. 相似文献
20.
An analytical investigation is presented to display the distribution of critical current flow through a low-angle grain boundary in a high-T c superconductor such as YBCO or Bi-2212 film. When a superconductor is subjected to a transport current or a magnetic field, the fluxoids are redistributed between the dislocations which comprise a low-angle grain boundary. A model considering the elastic interaction between a flux line and an edge dislocation is developed in this paper. Results of our model are consistent with those of the classic exponential model, while for high-angle grain boundaries with the misorientation angles ?? > 4°, this model is invalid. It is helpful by using our model to understand the mechanisms of the effect of low-angle grain boundaries on critical current density. 相似文献