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1.
A bi-epitaxial (001)YBa2Cu3O7−δ
/(110)BaZrO3/(001)CeO2 three-layer heterostructure has been grown on (100)SrTiO3 by laser ablation. The epitaxial relations between the layers making up the heterostructure were derived from x-ray diffraction
data. The I
cRn product for the bi-epitaxial Josephson junctions thus obtained was within 1–1.5 mV for 4.2 K, and 30–60 μV for 77 K. The normal resistance R
n=(2–5 Ω) was practically independent of temperature. The magnetic field dependences of I
c had typically a clearly pronounced main maximum, followed by distorted subsequent peaks. Interaction of the Josephson ac
current with self-induced electromagnetic waves at the 45° grain boundary and with external microwave radiation (f=11 GHz) produced current steps in the I-V characteristics of the bi-epitaxial junctions at the corresponding voltages.
Fiz. Tverd. Tela (St. Petersburg) 39, 1732–1738 (October 1997) 相似文献
2.
A. A. Petukhov B. E. Zhurtanov S. S. Molchanov N. D. Stoyanov Yu. P. Yakovlev 《Technical Physics》2011,56(4):520-525
The electroluminescent characteristics of an InGaAsSb/GaAlAsSb heterostructure LED emitting at 1.85 μm are studied in the
temperature range 20–200°C. It is shown that the emission power exponentially drops as P ≅ 0.4exp(2.05 × 103/T) with a rise in temperature primarily because of an increase in the Auger recombination rate. It is found that band-to-band
radiative recombination goes in parallel with recombination through acceptor levels, the latter causing the emission spectrum
to broaden. With a rise in temperature, the activation energy of the acceptor levels decreases by the law ΔE≅ 32.9 − 0.075T and the maximum of the LED’s emission spectrum shifts toward the long-wavelength range (hν
max = 0.693 − 4.497 × 10−4
T). Based on the dependence E
g
= hν
max − 0.5kT and experimental data, an expression is derived for the temperature variation of the bandgap in the In0.055Ga0.945AsSb active area, E
g
≅ 0.817 − 4.951 × 10−4
T, in the range 290 K < T < 495 K. The resistance of the heterostructure decreases exponentially with rising temperature as R
0 ≅ 5.52 × 10−2exp(0.672/2kT), while cutoff voltage U
cut characterizing the barrier height of a p−n junction decreases linearly with increasing temperature (U
cut = −1.59T + 534). It is found that the current through the heterostructure is due to the generation-recombination mechanism throughout
the temperature interval. 相似文献
3.
High field electrical switching on blown films of MoO3(60%)–P2O5(40%), MoO3(50%)–WO3(10%)–P2O5(40%), and MoO3(45%)–WO3(15%)–P2O5(40%) having different thicknesses was studied and compared. Switching was observed using two terminal samples. S-type current–voltage
characteristic (current-controlled negative resistance—CCNR) with memory was observed in molybdenum–phosphate glasses, but
N-type characteristic (voltage-controlled negative resistance—VCNR) with threshold in tungsten–molybdenum–phosphate glasses
was observed. The important observation was that with the addition of WO3 to binary MoO3–P2O5 led to a change of I–V characteristic from CCNR with memory to VCNR with threshold. The measurements of density and molar volume showed linear relation
between MoO3 content and density which decreased with the increase of MoO3 content. The samples’ thickness had no significant effect on threshold voltage. The attained results also indicated that
the electrode material had no effect on switching property of devices. The switching behavior of the devices did not show
any dependence on the polarity of the applied voltage. In terms of the effect of heat on the switching behavior of molybdenum–phosphate
glasses, it was found that threshold voltage decreases with increasing of temperature. Finally, the switching phenomenon was
explained by thermal (formation of crystalline filaments) and electronic models. 相似文献
4.
V. A. Kutasov L. N. Luk’yanova P. P. Konstantinov G. T. Alekseeva 《Physics of the Solid State》1997,39(3):419-422
A study has been made of the thermoelectric and galvanomagnetic properties of n-Bi2Te3−x
Sex solid solutions (x=0.3 and 0.36) in the temperature range 80–300 K. The lowest carrier concentrations, (0.8–1)×1018 cm−3, were obtained by displacing the solid solution from the stoichiometric to a Te-rich composition. At such carrier concentrations,
the second subband in the conduction band of n-Bi2Te3−x
Sex is not filled, which results in a growth of mobility because of the absence of interband scattering, and brings about an
increase of thermoelectric efficiency in the 80–120-K range.
Fiz. Tverd. Tela (St. Petersburg) 39, 483–487 (March 1997) 相似文献
5.
N. G. Kozlov S. L. Bondarev E. D. Skakovsky A. V. Baranovsky V. N. Knyukshto L. I. Basalaeva 《Journal of Applied Spectroscopy》2012,79(4):527-534
Hydrobenzophenanthrolinone derivatives were synthesized by three-component condensation of 8-aminoquinoline, aromatic aldehydes, and dimedone. The structures of the obtained substances were confirmed by NMR and IR spectroscopy and mass spectrometry. Spectral-luminescent investigations of the synthesized compounds showed that they were characterized by high oscillator strengths for allowed electronic transitions S n ← S 0 (n = 1–3). Low fluorescence quantum yields in EtOH (Φfl ~ 10–4–10–3) and an increase of the Φfl values in toluene (~10–2) at room temperature and with lowering the temperature to 77 K (Φfl ~ 10–1) for a number of the compounds under study were satisfactorily explained within the framework of Marcus theory. 相似文献
6.
S. Z. Li Z. B. Yan T. Wei S. J. Luo B. Liu K. F. Wang J.-M. Liu 《Applied Physics A: Materials Science & Processing》2009,94(4):975-980
Epitaxial orthorhombic YMnO3(YMO) thin films on (001) Nb:SrTiO3(NSTO) substrates were prepared by pulsed laser deposition. The weak ferromagnetism at low temperature, probably ascribed
to the stretched Mn-spin configuration along [010] direction, was identified. The dielectric anomaly at the spin–glass freezing
point indicates clearly a spin–phonon (magnetoelectric) coupling which can be modulated by electric field. The as-prepared
YMO/NSTO heterostructure exhibits significant current–voltage (I–V) rectifying effect over a broad temperature range. 相似文献
7.
Rectifying and photovoltaic properties of a La0.7Sr0.3CoO3−σ
/Si heterostructure have been experimentally studied. The heterostructure exhibits a rectifying behavior, similar to that
of the traditional diode. A photovoltaic effect is observed when the heterostructure is exposed to the laser with a wavelength
of 532 nm and a power of 6 mW/mm2. It is interesting to note that the peak photovoltages initially increase with decreasing temperature, followed by a decrease
at T<220 K. This reveals that the photovoltaic effect can be modulated by the intrinsic properties of the La0.7Sr0.3CoO3−σ
layer. 相似文献
8.
Arvind Nautiyal K. C. Sekhar N. P. Pathak R. Nath 《Applied Physics A: Materials Science & Processing》2009,97(1):205-210
The composite films of cesium nitrate (CsNO3) and poly(vinyl alcohol) (PVA) with varying composition were prepared using the solvent cast method. The hysteresis loop
characteristics show optimum remnant polarization (P
r
) of 2.75 μC/cm2 at 50 wt.% composition. The field emission scanning electron microscope images show a nearly homogeneous distribution of
CsNO3 grains in the 50 wt.% composite film. The temperature dependence of the remnant polarization shows a diffused transition
temperature range from the ferroelectric to the paraelectric phase and this has been attributed to the reduced enthalpy. The
butterfly features of the dielectric constant–voltage (ε–V) characteristics have been attributed to polarization switching. 相似文献
9.
An organic/inorganic heterojunction p-VOPc/n-Si was fabricated and its electrical properties were investigated. Temperature-dependent
dark current–voltage (I–V) characteristics of the heterojunction exhibited rectification behaviour with a rectification ratio of 405 at ±1 V and room
temperature. The current–voltage characteristics of the cell showed ohmic conduction at low voltages followed by a space charge-limited
current (SCLC) conduction dominated by an exponential trap distribution at higher voltages. At room temperature, the series
and shunt resistances were found to be approximately 1.4 and 100 kΩ, respectively. Diode ideality factor n was found to be 3.2 at room temperature and dropped to 1.9 at 363 K. Room temperature mobility of vanadyl phthalocyanine
(VOPc) was extracted from the I–V characteristics in the SCLC region and was found approximately 15.5 × 10−3 cm2 V−1 s−1. The effective barrier height, ФB, was estimated as 0.77 eV. The effect of temperature, on various heterojunction parameters was recorded under dark conditions
and at temperatures ranging from 300 to 363 K. 相似文献
10.
Hartmut St?cker Matthias Zschornak Juliane Seibt Florian Hanzig Susi Wintz Barbara Abendroth Jens Kortus Dirk C. Meyer 《Applied Physics A: Materials Science & Processing》2010,100(2):437-445
Motivated by the successful use of strontium titanate with different doping metals for memory cells on the basis of resistive
switching and the recent findings on the major importance of oxygen vacancy redistribution in this compound, the present work
shows the possibility of a non-volatile resistance change memory based on vacancy-doped SrTiO3. The formation of corresponding metal/SrTiO3−δ
junctions (δ>0) in an electric field will be discussed as well as the switching between ohmic and Schottky-type contact behavior. A notable
hysteresis in the current–voltage characteristics is used to carry out Write, Read, and Erase operations exemplifying the
memory cell properties of such junctions. But whereas the electric field-induced formation of Schottky-type junctions is explainable
by oxygen vacancy redistribution, the resistive switching needs to be discussed in terms of vacancies serving as electron
trap states at the metal/oxide interface. 相似文献
11.
Lee Dong Uk Kim Eun Kyu Cho Won-Ju Kim Young-Ho 《Applied Physics A: Materials Science & Processing》2011,102(4):933-938
A memory device with In2O3 nanocrystals embedded in a biphenyl-tertracarboxylic dianhydride-phenylen diamine (BPDA-PDA) polyimide layer on a ZnO layer
was fabricated, and its electrical properties were evaluated. Then, the transmittance efficiency in the structure of the BPDA-PDA
polyimide/In2O3 nanocrystals/ZnO/ITO/double polishing sapphire substrate was measured to be about 80% between 440 to 800 nm by ultraviolet-visible
transmittance spectroscopy. A bipolar switching current bistability by difference resistance appeared in the sweep voltage
rage from −7 to 7 V. It was considered that the bipolar behavior of current-voltage may originate from a resistance fluctuation
because of the electron charging effect in In2O3 nanocrystals by voltage sweeping, Fowler–Nordheim tunneling, space-charge-limited current, and the migration of O2− ions. 相似文献
12.
V. V. Lemanov A. V. Sotnikov E. P. Smirnova M. Weihnacht 《Physics of the Solid State》2002,44(11):2039-2049
Ceramic samples of (1−x)SrTiO3-xSrMg1/3Nb2/3O3 and (1−x)SrTiO3-xSrSc1/2Ta1/2O3 were prepared, and their dielectric properties were studied at x=0.005–0.15 and 0.01–0.1, respectively, at frequencies 10 Hz–1 MHz and at temperatures 4.2–350 K. A giant dielectric relaxation
was observed in the temperature range 150–300 K, and not so strong but well-developed relaxation was found in the temperature
range 20–90 K. The activation energy U and the relaxation time τ0 were determined to be 0.21–0.3 eV and from 10−11 to 10−12 s for the high-temperature relaxation and 0.01–0.02 eV and 10−8–10−10 s for the low-temperature relaxation, respectively. The additional local charge compensation of the heterovalent impurities
Mg2+ and Nb5+ (or Sc3+ and Ta5+) by free charge carriers or the host ion vacancies is suggested to be the underlying physical mechanism of the relaxation
phenomena. On the basis of this mechanism, the Maxwell-Wagner model and the model of reorienting dipole centers Mg2+ (or Sc3+) associated with the oxygen vacancy are proposed to explain the high-temperature relaxation with some arguments in favor
of the latter model. The polaron-like model with the Nb5+-Ti3+ center is suggested as the origin of the low-temperature relaxation. The reasons for the absence of ferroelectric phase transitions
in the solid solutions under study are also discussed.
From Fizika Tverdogo Tela, Vol. 44, No. 11, 2002, pp. 1948–1957.
Original English Text Copyright ? 2002 by Lemanov, Sotnikov, Smirnova, Weihnacht.
This article was submitted by the authors in English. 相似文献
13.
L. K. Aminov I. N. Kurkin S. P. Kurzin D. A. Lukoyanov I. Kh. Salikhov R. M. Rakhmatullin 《Journal of Experimental and Theoretical Physics》1997,84(1):183-189
Our studies involve measuring spin-lattice relaxation times for Nd3+ ions in yttrium-aluminum garnets over the temperature range 4–50 K at 9.25 and 36.4 GHz for different orientations of the
external magnetic field in relation to the crystallographic axes. The temperature dependence of the relaxation rate is described
by T
1
−1
=AT
n+b exp(−Δ/kT), where n varies from sample to sample, with n=1 for “perfect” samples (i.e., with the longest relaxation times). Here Δ is approximately 130 cm−1, which is the energy of the excited Kramers doublet of the neodymium ion closest to the ground state, and this makes it possible
to interpret the second term in T
1
−1
as the contribution of two-stage relaxation proceeding through the intermediate level Δ. A strong field dependence of these
processes has been discovered: when the frequency was increased fourfold, the relaxation rate increased by a factor of 10.
The effect is a specific manifestation of the degeneracy of the excited level, breaking of the symmetry of the crystalline
field due to lattice defects, and the prevalence of deformations of a certain type in the spin-lattice interaction.
Zh. éksp. Teor. Fiz. 111, 332–343 (January 1997) 相似文献
14.
The temperature dependence of the principal values of the refractive index in Sr1−x
CaxTiO3 (x=0.014) has been measured in the 17–275 K range under various conditions of sample illumination with 1.96 eV photons. The
spontaneous photorefractive contribution δn
ph to the temperature-induced variation of the refractive index of Sr1−x
CaxTiO3, which appears after illumination of the sample in the ferrophase (transition temperature T
c=32 K) and persists in the paraphase under heating up to 150 K, has been separated. The photoinduced polarization has been
estimated.
Fiz. Tverd. Tela (St. Petersburg) 39, 711–713 (April 1997) 相似文献
15.
B. Dong X.S. Xu X.J. Wang T. Yang Y.Y. He 《Applied physics. B, Lasers and optics》2007,89(2-3):281-284
Er3+-doped Al2O3 has been prepared by a sol–gel method, using aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of erbium nitrate [Er(NO3)3·5H2O]. The phase structure of θ-(Al,Er)2O3 phase was obtained for the 0.1 mol. % Er3+-doped Al2O3 at the sintering temperature of 1273 K. The green and red up-conversion emissions centered at about 523, 545 and 660 nm,
corresponding respectively to the 2
H
11/2, 4
S
3/2→4
I
15/2 and 4
F
9/2→4
I
15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The temperature dependence of green up-conversion emissions
was studied over a wide temperature range of 295–725 K, and reasonable agreement between the calculated temperatures obtained
by the fluorescence intensity ratio theory and the measured temperature was obtained, which proved that Er3+-doped Al2O3 has a good potential for the development of high-temperature sensors. It has some advantages compared to glasses due to its
higher thermal and mechanical resistance and allows measurements in a large temperature range.
PACS 78.55.Hx; 81.40.Tv 相似文献
16.
Sarath C. Puthentheradam Dieter K. Schroder Michael N. Kozicki 《Applied Physics A: Materials Science & Processing》2011,102(4):817-826
The feasibility of a storage element with inherent rectifying or isolation properties for use in passive memory arrays has
been demonstrated using a programmable metallization cell structure with a doped (n-type) silicon electrode. The Cu/Cu–SiO2/n-Si cell used in this study switches via the formation of a nanoscale Cu filament in the Cu–SiO2 film which results in the creation of a Cu/n-Si Schottky contact with soft reverse breakdown characteristics. The reverse bias leakage current in the on-state diode is
dependent on the programming current employed as this influences the area of the electrodeposit and hence the area of the
Cu/n-Si junction. The programming current also controls the on-state resistance of the device, allowing multi-level cell (MLC)
operation, in which discrete resistance levels are used to represent multiple logical bits in each physical cell. The Cu/Cu–SiO2/n-Si elements with heavily doped silicon electrodes were readily erasable at voltage less than −5 V which allows them to be
re-programmed. Lightly doped silicon electrode devices were not able to be erased due to their very high reverse breakdown
voltage but exhibited extremely low leakage current levels potentially allowing them to be used in low energy one-time programmable
arrays. 相似文献
17.
Polycrystalline ceramics of the perovskite solid solution 0.5Pb(Ni1/3Nb2/3)O3-(0.5-x)-Pb(Zn1/3Nb2/3)O3–xPb(Zr1/2Ti1/2)O3; x=0.0–0.5 (PNN–PZN–PZT) were synthesized by a modified columbite method. Highly dense ceramics lacking parasitic pyrochlore
phases were prepared at a calcination temperature of 950 °C by using a double-crucible configuration, excess PbO (2 mol %),
and a fast heating/cooling rate (20 °C/min). The ceramics were characterized by a variety of techniques including X-ray diffraction,
ferroelectric hysteresis loop measurements, field-induced longitudinal strain measurements, and electron microscopy. It was
observed that the remanent polarization exhibited a significant increase with increasing x. In addition, the squareness of
the hysteresis loop increased quasi-linearly as the molar fraction of PZT increased. The maximum spontaneous polarization
and remanent polarization for the x=0.5 composition were 31.9 μC/cm2 and 25.2 μC/cm2, respectively. Moreover, the data were analyzed to show the evolution of the micro-domain state as a function of the molar
fraction of PZT.
PACS 77.22.-d; 77.80.Bh; 77.84.Dy; 61.10.Nz; 77.80.Dj 相似文献
18.
L. S. Ewe I. Hamadneh H. Salama N. A. Hamid S. A. Halim R. Abd-Shukor 《Applied Physics A: Materials Science & Processing》2009,95(2):457-463
The magnetotransport and magnetoresistive (MR) properties of manganese-based La0.67Ca0.33MnO3 perovskite with different grain sizes are reported. The electrical resistivity was measured as a function of temperature
in magnetic fields of 0.5 and 1 T. The insulator–metal transition temperature, T
IM, shifted to a higher temperature with the application of the magnetic field. In zero field, T
IM is almost constant (∼271 K) for all samples except for the sample with the largest grain size, where T
IM=265 K. The temperature dependence of resistivity was fitted with several equations in the metallic (ferromagnetic) region
and the insulating (paramagnetic) region. The density of states at the Fermi level, N(E
F), and the activation energy of electron hopping were estimated by fitting the resistivity versus temperature curves. The
ρ–T
2 curves are nearly linear in the metallic regime, but the ρ–T
2.5 curves exhibit a deviation from linearity. The variable range hopping model and small polaron hopping model fit the data
well in the high-temperature region, indicating the existence of the Jahn–Teller distortion that localizes the charge carriers.
MR was found to increase with an increase in the magnetic field, an effect which is attributed to the intergrain spin tunneling
effect. 相似文献
19.
E. S. Itskevich 《Journal of Experimental and Theoretical Physics》1998,86(4):805-810
A study is made of the properties of the homologous series of mercury HTSC-cuprates HgBa2Can−1CunO2n
+2+δ with n=1–8. Experiments are conducted under pressure for samples with n=1–5. The Hg-1223 and Hg-1234 phases were synthesized using a controlled high pressure chamber. The oxygen content of an initial
mixture corresponding to the Hg-1234 phase was varied by changing the composition of the initial BaO/BaO2 oxides. The dependence of the superconducting transition temperature T
c
on the lattice constant a (and, therefore, on the oxygen content) and of T
c
max
and dT
c
max
/dp on n are convex upward up to n=4, 5. The maximum values always correspond to the Hg-1223 phase. Experimental T
c
max
(n) curves for the phases with n=1–6 and dT
c
max
/dp curves for n=1–5 are compared with Anderson’s theory (the so-called RVB model). A general analysis of these results indicates that the
mercury cuprates have an ideal structure for HTSC. The Hg-1223 phase is the “champion” in this ideal structure and the critical
temperature corresponding to this phase (T
c
=135 K) is the highest at atmospheric pressure.
Zh. éksp. Teor. Fiz. 113, 1474–1483 (April 1998) 相似文献
20.
Y.W. Chen Y.C. Liu S.X. Lu C.S. Xu C.L. Shao 《Applied physics. B, Lasers and optics》2006,84(3):507-510
In-doped zinc oxide (ZnO:In) nanorods were grown onto SiO2/n-Si substrate without catalyst in aqueous solution. The ZnO:In nanorods/SiO2/n-Si heterostructure photovoltaic device was prepared. The structural and photoelectric properties of the as-grown ZnO:In nanorods were analyzed. ZnO:In nanorods had a strong and broad UV surface photovoltage response in the range of 300–400 nm, and the bands were identified. The photoelectric conversion properties of ZnO:In nanorods/SiO2/n-Si heterostructure were investigated. ZnO:In/SiO2/n-Si heterostructure showed a wide range photocurrent spectral response with high intensity in the UV and visible region. The rectifying behavior of this heterostructure was observed. Moreover, the device had a low turn-on voltage and a high breakdown voltage. Current–voltage characteristic was studied for the heterostructure, and the open-circuit voltage and short-circuit current were obtained. PACS 73.40.Lq; 85.35.Be; 81.16.Dn 相似文献