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1.
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
2.
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
3.
Yu. A. Lupitskaya D. A. Kalganov K. V. Abdrakhmanova 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(1):87-91
Features of the formation of lead-ferroniobate compounds in the xBaCO3–(1 – x)PbO–Fe2O3–Nb2O5 system by solid-phase synthesis are investigated. For perovskite-type lead-ferroniobate solid solution, a single-phase concentration region is revealed at 1233 K. The crystalline structures of the synthesized compounds are refined using Rietveld analysis and the Pm3?m and R3m space groups. Ceramic samples of lead ferroniobate are studied by scanning electron microscopy. 相似文献
4.
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
5.
L. T. Denisova N. V. Belousova N. A. Galiakhmetova V. M. Denisov E. O. Golubeva 《Physics of the Solid State》2018,60(7):1303-1307
Differential scanning calorimetry has been used to study the influence of temperature on the heat capacity of synthesized vanadates Zn2V2O7, (Cu0.56Zn1.44)V2O7, and (Cu1.0Zn1.0)V2O7. It is found that dependences Cp = f(T) have extremes. The thermodynamic properties of Zn2V2O7 have been determined. 相似文献
6.
7.
Huanfu Zhou Hong Wang Minghui Zhang Xi Yao 《Applied Physics A: Materials Science & Processing》2009,95(2):513-516
A new Li2O–Nb2O5–TiO2 (LNT) ceramic with the Li2O:Nb2O5:TiO2 mole ratio of 5.5:1:7 was prepared by solid state reaction route. The phase and structure of the ceramic were characterized
by X-ray diffraction and scanning electron microscopy (SEM). The microwave dielectric properties of the ceramics were studied
using a network analyzer. The microwave dielectric ceramic has low sintering temperature (∼1075°C) and good microwave dielectric
properties of ε
r=42, Q×f=16900 GHz (5.75 GHz), and τ
f
=63.7 ppm/°C. The addition of B2O3 can effectively lower the sintering temperature from 1075 to 875°C and does not induce degradation of the microwave dielectric
properties. Obviously, the LNT ceramics can be applied to microwave low temperature-cofired ceramics (LTCC) devices. 相似文献
8.
Kiichirou?Koyasu Wilko?Westh?user Marco?Niemietz Jan?Heinen Gerd?Gantef?r 《Applied Physics A: Materials Science & Processing》2009,96(3):679-684
Using time-resolved photoelectron spectroscopy, the decay channels of AuO2− and Au2O2− following photoexcitation with 3.1-eV photons have been studied. For AuO2−, a state with a rather long lifetime of 30 ps has been identified. Its decay path could not be determined but photodesorption
can be excluded. For Au2O2−, the spectra indicate O2 desorption after 3.1-eV photoexcitation on a time scale of 1 ps. While comparing these results on Au
n
O2− with analogous data on Ag
n
O2− clusters, a discernible pattern emerges: for dissociatively bound O2(AuO2−, Ag3O2−), there are long-living excited states which do not decay by oxygen desorption, while for molecular chemisorption (Au2O2−, Ag2O2−, Ag4O2−, Ag8O2−), the 3.1-eV photoexcitation triggers fast O2 desorption with a high quantum yield. 相似文献
9.
Composite solid electrolytes in the system (1???x)Li2CO3–xAl2O3, with x?=?0.0–0.5 (mole), were synthesized by a sol–gel method. The synthesis carried out at low temperature resulted in voluminous and fluffy products. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy/energy-dispersive X-ray, Fourier transform infrared spectroscopy and AC impedance spectroscopy. Structural analysis of the samples showed an amorphous feature of Li2CO3 and traces of α-LiAlO2, γ-LiAlO2 and LiAl5O8. The prepared composite samples possess high ionic conductivities at 130–180 °C on account of the presence of lithium aluminates as well as the formation of a high concentration of an amorphous phase of Li2CO3 via this sol–gel preparative technique. 相似文献
10.
The specific heat of [NH2(CH3)2]2ZnCl4 was measured calorimetrically in the temperature region 80–300 K. As the temperature T decreases, the C p (T) dependence indicates a phase transition sequence, with the phase transition at T6=151 K observed for the first time. The thermodynamic characteristics of the crystal were refined. The transformation occurring at T2=298.3 K is shown to be an incommensurate-commensurate phase transition. 相似文献
11.
G. N. Gerasimov M. M. Grekhov V. F. Gromov M. I. Ikim E. Yu. Spiridonova L. I. Trakhtenberg 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(4):709-713
The structural characteristics, valence states, and distribution of cerium ions between the components in In2O3–CeO2 and SnO2–CeO2 nanocomposites fabricated using the impregnation method were studied. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) were used to show that, during impregnation, cerium ions are not included into In2O3 crystals and are disposed only on their surface in the form of nano-sized crystallites or amorphous clusters. On the other side, under the contact of CeO2 clusters with a surface of SnO2 matrix crystals, cerium ions penetrate into the surface layer of these crystals. In contrast to an In2O3–CeO2 system, where the addition of CeO2 does not affect the conduction activation energy, where cerium oxide is added to SnO2, the observed increase in the resistance of a SnO2–CeO2 composite is accompanied by a sufficient increase in activation energy. These data and the XPS spectra confirm the modification of the surface layers of conductive SnO2 crystals as, a result of the penetration of cerium ions into these layers. 相似文献
12.
Organic–inorganic hybrid sample [N(C4H9)4]2Cu2Cl6 was prepared via the reaction between copper chloride and tetrabutylammonium chloride. The compound was characterized by
X-ray powder diffraction, IR, Raman, differential scanning calorimetry (DSC), DTA-TGA analysis and electrical impedance spectroscopy.
DSC studies indicate a presence of one-phase transition at 343 K. The complex impedance of compound [N(C4H9)4]2Cu2Cl6 have been investigated in temperature and frequency ranges 300–380 K and 200 Hz–5 MHz, respectively. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit model. The circuits consist of the parallel combination
of bulk resistance R
p and constant phase elements CPE. The frequency dependence of the conductivity is interpreted in term of Jonscher's law: s(w) = sdc + Awn \sigma (\omega ){ } = {\sigma_{\rm{dc}}} + { }A{\omega^n} . The conductivity follows the Arrhenius relation. The variation of the value of these elements with temperatures confirmed
the availability of the phase transition at 343 K detected by DSC and electrical measurements. 相似文献
13.
Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep
metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles
evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt
laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains
will anneal and adjust to local equilibrium but some will persist metastably depending on the time–temperature regime and
melt/glass transformation. 相似文献
14.
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
15.
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
16.
Jiaming Li Feifei Wang Xiaomei Qin Min Xu Wangzhou Shi 《Applied Physics A: Materials Science & Processing》2011,104(1):117-122
In the present work, (1−x)(0.935Bi0.5Na0.5TiO3–0.065BaTiO3)–xKNbO3 (BNT–BT–KN, BNT–BT–100xKN) ceramics with x ranging from 0 to 0.1 were prepared by the conventional ceramic fabrication process. A large electrostrictive coefficient
of ∼10−2 m4 C−2 is obtained with the composition x ranging from 0.02 to 0.1, which is close to the well-known electrostrictive material Pb(Mg1/3Nb2/3)O3. Under an electric field of 4 kV/mm, the electrostrictive strain can reach as high as 0.08%. Besides, the electric field
induced strain behavior indicates a temperature independent behavior within the temperature range of 20 to 150°C. The large
electrostrictive strain is suggested to be ascribed to the formation of non-polar (NP) phase developed by the KNbO3 substitution, and the high electrostrictive coefficient of BNT–BT–KN ceramics makes them great candidates to be applied in
the new solid-state actuators. 相似文献
17.
Silver-based quaternary glasses were prepared by splat quenching technique. X-ray diffraction and differential scanning calorimetry
were done for confirming their amorphous nature. The conductivity of the glasses was measured in the frequency range from
1 Hz to 32 MHz from room temperature to 373 K. Conductivity data, which obeys the Arrhenius type behavior, shows minimum at
30 mol% Ag2O, suggesting that the conductivity mechanisms are different above and below these two regions. The minimum in conductivity
is accompanied by an inverse behavior of activation energy. Experimental data suggests that a polaron hopping mechanism operates
in the electronically conducting domain of 20 ≤ × ≤ 30, and an interstitial pair mechanism operates in the ionically conducting
domain of 35 ≤ × ≤ 55. 相似文献
18.
Yan-Ying Wang Yan-Jing Hao Qiong-Yu Lai Ji-Zheng Lu Yuan-Duan Chen Xiao-Yang Ji 《Ionics》2008,14(1):85-88
A new Li4Ti5O12–SnO2 composite anode material for lithium-ion batteries has been prepared by loading SnO2 on Li4Ti5O12 to obtain composite material with improved electrochemical performance relative to Li4Ti5O12 and SnO2. The composite material was characterized by X-ray diffraction and scanning electron microscopy. The results indicated that
SnO2 particles have encapsulated on the surface of the Li4Ti5O12 uniformly and tightly. Electrochemical results indicated that the Li4Ti5O12–SnO2 composite material increases the reversible capacity of Li4Ti5O12 and has good cycling reliability. At a current rate of 0.5 mA/cm2, the material delivered a discharge capacity of 236 mAh/g after 16 cycles. It suggests the existence of synergistic interaction
between Li4Ti5O12 and SnO2 and that the capacity of the composite is not a simple weighted sum of the capacities of the individual components. In the
composite material, SnO2 can act as a bridge between the spinel particles to reduce the interparticle resistance and as a good material for the Li
intercalation/deintercalation. Thus, electrochemical performance of the Li4Ti5O12 spinel can be improved by the surface modification with SnO2, and the stability of Li4Ti5O12 also serves to buffer the internal stress caused by the volume changes in lithium insertion and extraction reactions. 相似文献
19.
The heat capacity of the [[N(C2H5)4]2CdBr4 crystal is measured by the calorimetric method in the temperature range from 80 to 300 K. It is revealed for the first time that the temperature dependence of the heat capacity C p (T) exhibits an anomaly associated with the first-order phase transition occurring at the temperature T 1 = 226.5 K. A long relaxation of the temperature of the crystal is observed in the temperature range 150–165 K. 相似文献
20.
S. I. Vorob’ev D. S. Andrievskii S. G. Barsov A. L. Getalov E. I. Golovenchits E. N. Komarov S. A. Kotov A. Yu. Mishchenko V. A. Sanina G. V. Shcherbakov 《Journal of Experimental and Theoretical Physics》2016,123(6):1017-1024
A comparative μSR study of ceramic samples of the EuMn2O5 and Eu0.8Ce0.2Mn2O5 multiferroics is performed in the temperature range from 15 to 300 K. It is found that the Ce doping of the EuMn2O5 sample slightly reduces the temperature of the magnetic phase transition from T N = 45 K for the EuMn2O5 sample to T N = 42.5 K for the Eu0.8Ce0.2Mn2O5 sample. Below the temperature T N for both samples, there are two types of localization of a thermalized muon with different temperature dependences of the precession frequency of the magnetic moment of the muon in an internal magnetic field. The higher frequency in both samples refers to the initial antiferromagnetic matrix. The behavior of this frequency in Eu0.8Ce0.2Mn2O5 follows the Curie–Weiss law with the exponent β = 0.29 ± 0.02, which differs from the value β = 0.39 standard for 3D Heisenberg magnetics and is observed in EuMn2O5, because of the strong frustration of the doped sample. The temperature-independent low frequency is due to the presence of Mn3+–Mn4+ ferromagnetic pairs located along the b axis of the antiferromagnetic matrix and in the regions of phase separation, which contain such ion pairs and e g electrons recharging them. In both samples, polarization losses are the same (about 20%) and are associated with the formation of Mn4+–Mn4+ + Mu complexes near Mn3+–Mn4+ ferromagnetic pairs. In the temperature interval from 25 to 45 K, the separation of the Eu0.8Ce0.2Mn2O5 structure into two fractions where the relaxation rates of polarization of muons differ by an order of magnitude is revealed. This effect is due to a change in the state of regions of phase separation (1D superlattices) at the indicated temperatures. Such effect in EuMn2O5 is significantly weaker. 相似文献