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1.
The heat capacity (C
p
0) of the tellurite glasses
$\begin{gathered}
(TeO_2 )_{0.70} (ZnO)_{0.15} (Na_2 O)_{0.10} (Bi_2 O_3 )_{0.05} (I), \hfill \\
(TeO_2 )_{0.75} (ZnO)_{0.10} (Na_2 O)_{0.10} (Bi_2 O_3 )_{0.05} (II),and \hfill \\
(TeO_2 )_{0.75} (ZnO)_{0.15} (Na_2 O)_{0.05} (Bi_2 O_3 )_{0.05} (III) \hfill \\
\end{gathered}
$\begin{gathered}
(TeO_2 )_{0.70} (ZnO)_{0.15} (Na_2 O)_{0.10} (Bi_2 O_3 )_{0.05} (I), \hfill \\
(TeO_2 )_{0.75} (ZnO)_{0.10} (Na_2 O)_{0.10} (Bi_2 O_3 )_{0.05} (II),and \hfill \\
(TeO_2 )_{0.75} (ZnO)_{0.15} (Na_2 O)_{0.05} (Bi_2 O_3 )_{0.05} (III) \hfill \\
\end{gathered}
相似文献
2.
A new series of superconducting mercury-based layered cuprates has been synthesized. X-ray diffraction indicates that the compounds with formula Hg0.8W0.2Sr2Y1–x
Ca
x
Cu2O6+ (0.3x0.6) exhibit the 1212 structure with space groupP
4/mmm
. The investigation of superconductivity determined by electrical resistance measurement shows that the superconducting transition temperature (T
c
, onset) of Hg0.8W0.2Sr2Y0.4Ca0.6Cu2O6+ is up to 94 K. 相似文献
3.
S. L. Young T. C. Wu L. Horng C. H. Lin H. Z. Chen M. C. Kao C. R. Ou N. F. Shih J. B. Shi 《Journal of Superconductivity and Novel Magnetism》2010,23(6):953-956
The ceramic composites, (La0.7Pb0.3MnO3)1−x
(SiO2)
x
, with diluted magnetic properties are prepared using solid-sate sintering route. Magnetization processes of (La0.7Pb0.3MnO3)1−x
(SiO2)
x
composites are explored in this study. Ferromagnetism is gradually attenuated due to the magnetic dilution induced by the
increase of SiO2 content. Clearly, irreversible behavior is observed in the zero-field cooling and the field cooling (ZFC–FC) curves at a
low field of 100 Oe. Saturation magnetization decreases as x increases while ferromagnetic transition temperature remains around 346 K for all composites. All the composites exhibit
ferromagnetic hysteresis behavior which can be modeled by the law of the approach to saturation in the form M=M
S(1−a/H). The term a/H expresses the deviation of magnetization from saturation. The smaller factor a for La0.7Pb0.3MnO3-rich samples results in sharper square curve which should be associated with the long-range spin order of ferromagnetic coupling. 相似文献
4.
Masashi Tanaka Hiroyuki Sasakura Yoshiya Akagi Shigeki Tsukui Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1479-1483
New Pb-based 1212 layered cuprates containing sulfur have been synthesized in the (Pb0.75S0.25) Sr2 (Y1−x
Ca
x
) Cu2O
z
system. X-ray diffraction analysis shows that the almost single-phase samples are obtained within a region of 0.0≤x≤0.5. The crystal structure of each sample has a tetragonal symmetry with the typical lattice constants a=0.3837 nm and c=1.186 nm. As Ca content x is increasing, the semiconductor-like behavior is suppressed. But after only annealing under ambient O2 pressure, none of the samples show any trace of superconductivity. On the other hand, when the samples are annealed under
high O2 pressure of about 13.6 MPa, they show resistivity dropping phenomenon in a region of 0.5≤x≤0.7. Among them, the lowest resistivity sample with x=0.6 has an onset temperature of the resistivity dropping at about 22.5 K. Moreover, this sample shows a diamagnetic signal
at about 21.5 K. These phenomena are attributed to superconductivity. 相似文献
5.
The electrical conductivity, band gap, dielectric permittivity, and molar polarizability of Zn2(Ti
a
Sn
b
)1 − x
Zr
x
O4 solid solutions have been determined. All of the synthesized samples are dielectrics with semiconducting behavior of conductivity.
The phase diagram of the Zn2TiO4-Zn2SnO4-Zn2ZrO4 system is presented. 相似文献
6.
Hiroyuki Sasakura Yoshiya Akagi Masashi Tanaka Shigeki Tsukui Motoaki Adachi 《Journal of Superconductivity and Novel Magnetism》2010,23(7):1381-1384
New Pb-based layered cuprates containing boron with the 1232 structure have been synthesized in the (Pb0.5B0.5)Sr2(Er3−x−y
Ce
x
Sr
y
)Cu2O
z
system. Nearly the single 1232 phase samples are obtained for the nominal composition of 1.6≤x≤1.9 and y=0.2. A sample with the composition of (Pb0.5B0.5)Sr2(Er1.2Ce1.6Sr0.2)Cu2O
z
shows resistivity-dropping phenomenon below 10 K and it shows a diamagnetic signal at about 9.0 K, though the superconducting
volume fraction is very small. From these results, the sample may well be a new Pb-based superconductor with the 1232 structure. 相似文献
7.
New NASICON type materials of composition, Li3−2x
Al2−x
Sb
x
(PO4)3 (x = 0·6 to 1·4), have been prepared and characterized by powder XRD and IR. D.C. conductivities were measured in the temperature
range 300–573 K by a two-probe method. Impedance studies were carried out in the frequency region 102−106 Hz as a function of temperature (300–573 K). An Arrhenius behaviour is observed for all compositions by d.c. conductivity
and the Cole-Cole plots obtained from impedance data do not show any spikes on the lower frequency side indicating negligible
electrode effects. A maximum conductivity of 4·5 × 10−6 S cm−1 at 573 K was obtained for x = 0·8 of the Li3−2x
Al2−x
Sb
x
(PO4)3 system. 相似文献
8.
A. Younis A. Hussain M. Asghar A. Manzoor S. Javed 《Journal of Superconductivity and Novel Magnetism》2011,24(4):1327-1332
The dielectric properties of Cu0.5Tl0.5Ba2Ca2−q
Mg
q
Cu3O10−δ
(q=0, 0.5, 1.0 1.5) superconductor samples were studied at two temperatures of 80 and 290 K by capacitance (C) and conductance (G) measurements with the test frequency (f) in the range of 10 KHz to 10 MHz. We have presented the measurements of the dielectric constants (ε′ and ε″), dielectric loss factor (tan δ) and ac-conductivity (σ
ac) as a function of frequency and temperature. A negative capacitance (NC) experience has been observed, which is most likely
due to different contact electrodes and superconductor samples’ Fermi levels. Since metals have their Fermi levels higher
than ceramics, there is a flow of the carriers from the ceramic samples towards the metal electrodes. The dielectric polarization
phenomenon is observed, which is due to dislodgment of mobile charges from their equilibrium position relative to fixed charges
of the reservoir layer. The improved inter plane coupling promoted by Mg substitution at Ca site would change the dielectric
response of Cu0.5Tl0.5Ba2Ca2−q
Mg
q
Cu3O10−δ
superconductors. To observe such effects in Mg doped Cu0.5Tl0.5Ba2Ca2−q
Mg
q
Cu3O10−δ
superconductors, di- electric measurements were carried out both at room temperature (290 K) and in the superconducting state
closer to the boiling point of liquid nitrogen (80 K). The excess conductivity arising due to superconducting state of material
has been determined, and its role in the mechanism of superconductivity is suggested. The negative dielectric constant (ε′) and dielectric loss factor (tan δ) show strong dispersion at low frequencies. The lower thermal agitation at 80 K may enhance the polarizability and hence
the dielectric constants (ε′ and ε″). 相似文献
9.
Hengwei Liu Aimin Sun Yanzhong Lu Yaotong Ma Jinyuan Ma Guidan Wei Long Zheng 《Journal of Superconductivity and Novel Magnetism》2010,23(8):1525-1528
A series of polycrystalline samples of Mg1−x
Zn
x
(B1−x
C
x
)2 (x=0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) were synthesized by a conventional solid-state reaction method under a background
pressure about 10−3 Pa. Phase identification, crystal structure and superconducting transition temperature (T
c) were studied by means of X-ray diffraction (XRD) and resistivity measurements. The results indicated that the lattice parameters
a and c show no clear trend in their changes with increasing doping level, and it turned out that the dopants had a marked effect
on the crystal-lattice parameters and changed the crystal structure of the samples. The T
c for Mg1−x
Zn
x
(B1−x
C
x
)2 decreased with C and Zn doping, but the rate of decrease was slower than single C-doped. We propose that the suppression
of T
c by doping originates largely from the structural change. 相似文献
10.
The effects of Cr in ErBa2(Cu1–x
Cr
x
)O7– (x=0–0.1) superconductor have been investigated. The critical temperature, which was determined by DC electrical resistance measurements, showed no suppression of the onset temperature (T
c onset) within the substitution range. The transition width (T
c
) broadened as the Cr content is increased. The normal state changes from the metal-like to semimetal/semiconductor-like for x0.03. Micrographs from the scanning electron microscope, X-ray diffraction pattern, and energy dispersive X-ray analysis results are used to describe the superconducting properties of these materials. The orthorhombic structure was preserved throughout the substitution range. Some possible roles of Cr in the system are discussed. 相似文献
11.
S. M. Hasnain M. Mumtaz Nawazish A. Khan 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1653-1657
The effect of synthesis temperature on the superconducting properties of (Cu1−x
Tl
x
)Ba2Ca3Cu4O12−δ
(CuTl-1234) samples has been explored. Almost all the superconducting parameters studied in this research work are observed
to be suppressed with the increase of synthesis temperature beyond 880 °C, which may be due to impurities caused by the volatility
of some constituents such as thallium and oxygen deficiencies as well in the final compound. The Fluctuation Induced Conductivity
(FIC) analysis has shown a decrease in the cross-over temperature (T
0) and the shift of three-dimensional (3D) Aslamasov–Larkin (AL) regions to the lower temperature with the increase of synthesis
temperature beyond 880 °C. A direct correlation between the cross-over temperature (T
0), the zero temperature coherence length {ξ
c
(0)}, the zero resistivity critical temperature {T
c
(R=0)} as well as carrier concentration has also been observed. 相似文献
12.
A. I. Svitan’ko S. A. Novikova D. V. Safronov A. B. Yaroslavtsev 《Inorganic Materials》2011,47(12):1391-1395
Li1 + x
Ti2 − x
Cr
x
(PO4)3 NASICON-type materials have been prepared and characterized by X-ray diffraction, scanning electron microscopy, and impedance
spectroscopy. The results demonstrate that Cr3+ doping increases the ionic conductivity of LiTi2(PO4)3 within the single-phase region of the doped material, which extends to x = 0.7. From temperature-dependent ionic conductivity data, the activation energy for lithium transport through interstitial
sites and the enthalpy of defect formation in LiTi2(PO4)3 are estimated at 30.0 ± 0.5 and 56 ± 1 kJ/mol, respectively. 相似文献
13.
Ceramic powders of (Nd
x
Gd1−x
)2Zr2O7 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were synthesized by chemical-coprecipitation followed by calcination method, and were
then pressureless-sintered at 1,600 °C for 10 h in air. Phase constituents and morphologies of the synthesized powders and
sintered ceramics were identified by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron
microscopy (TEM). A high-temperature dilatometer and a laser-flash method were used to analyze the thermal expansion coefficient
and thermal diffusion coefficient of different ceramics from room temperature up to 1,400 °C. Thermal conductivity was calculated
from thermal diffusivity, density, and specific heat. (Nd
x
Gd1−x
)2Zr2O7 (0.1 ≤ x ≤ 1.0) ceramics are with a pyrochlore-type structure; however, pure Gd2Zr2O7 exhibits a defective fluorite-type structure. The average linear thermal expansion coefficients of different (Nd
x
Gd1−x
)2Zr2O7 ceramics decrease with increasing the value of x from 0 to 1.0 in the temperature range of 25–1,400 °C. The thermal conductivities of (Nd
x
Gd1−x
)2Zr2O7 ceramics are located within the range of 1.33 to 2.04 W m−1 K−1 from room temperature to 1,400 °C. 相似文献
14.
H. Sasakura Y. Akagi M. Tanaka S. Tsukui M. Adachi 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1623-1626
New Pb-based 1222 cuprates containing phosphorus have been synthesized in the (Pb,P)Sr2(Eu,Ce,Sr)2 Cu2O
z
system. From X-ray powder diffraction study, almost the single 1222 phase samples are found to be obtained in a considerable
wide composition area of 0.3≤x≤1.2 for the nominal composition of (Pb0.75P0.25)Sr2(Eu1.9−x
Ce
x
Sr0.1) Cu2O
z
. The crystal structure for each sample has a tetragonal symmetry and the typical lattice parameters are a=0.3851 nm and c=2.922 nm. After annealing under 143 atm O2 atmosphere at 400 °C, a sample with x=0.3 among the almost-single phase samples shows an onset of resistivity-drop at the highest temperature of about 22 K and
zero-resistivity at the highest temperature of about 12 K, then this sample also shows an onset of diamagnetic signal at about
20 K. These phenomena are found to originate from superconductivity of the new 1222 phase. 相似文献
15.
The multicomponent refractory oxide system Zn2 − x
(Ti
a
Zr
b
)1 − x
Fe2x
O4 (a + b = 1; a: b = 1: 5, 1: 4, 1: 3, 1: 2, 1: 1, 2: 1, 3: 1, 4: 1; x = 0–1.0; Δx = 0.05) has been studied by X-ray diffraction, using samples prepared by melting appropriate metal oxide mixtures in a low-temperature
hydrogen-oxygen plasma. Two phases, both with wide homogeneity ranges, have been identified: α-phase, with a cubic inverse
spinel structure, and β-phase, with a tetragonal inverse spinel structure. The phase boundaries in the system have been determined.
Structural data are presented for about 100 solid solutions. 相似文献
16.
N. P. Stepanov V. Yu. Nalivkin L. D. Ivanova Yu. V. Granatkina 《Inorganic Materials》2012,48(3):234-237
The magnetic susceptibility (χ) of crystals of (Bi2 − x
Sb
x
)Te3 (0 < x < 1) solid solutions has been measured at temperatures from 2 to 400 K. The χ of the crystals containing 10 and 25 mol %
Sb2Te3 increases with temperature in the range 50 to 220 K, where the Hall coefficient of Bi2Te3 increases anomalously. The increase in diamagnetic susceptibility and Hall coefficient with temperature is shown to be caused
by a reduction in light-hole concentration, accompanied by a decrease in light-hole effective mass. With increasing Sb2Te3 content, the shape of the χ(T) curve changes as a consequence of changes in band structure, which increase the influence of heavy, paramagnetic holes. 相似文献
17.
We have synthesized Ba1 − x
(Zn1/2W1/2)O3 − x
and Ba(Zn1/2 − y
W1/2)O3 − y/2 barium tungstates with different deviations from cation stoichiometry (x = 0.01–0.05, y = 0.01–0.05), determined the phase composition of ceramics fabricated from the tungstates, and investigated their electrical
properties. Even slight deviations from cation stoichiometry in Ba(Zn1/2W1/2)O3 lead to the formation of the scheelite phase BaWO4, and its content increases with heat-treatment temperature. Barium or zinc deficiency in the systems studied improves the
sintering behavior of Ba(Zn1/2W1/2)O3 and increases the degree of 1: 1 B-site cation ordering, which in turn ensures an increase in microwave quality factor, Q. 相似文献
18.
Benjaram M. Reddy Gunugunuri K. Reddy Komateedi N. Rao Ibram Ganesh Jose M. F. Ferreira 《Journal of Materials Science》2009,44(18):4874-4882
Titania–silica, titania–alumina, and titania–zirconia mixed oxides (1:1 molar ratio) were prepared by a microwave-induced
solution combustion synthesis technique. The prepared materials were characterized by thermogravimetry/differential thermal
analysis, X-ray diffraction (XRD), Raman spectroscopy, BET surface area, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible
diffuse reflectance spectroscopic (UV–Vis DRS), and Fourier transform infrared (FTIR) techniques to assess their physicochemical
properties. Their photocatalytic activity for the degradation of phenol in aqueous solution under sunlight was studied. XRD
and Raman studies revealed the presence of titania in the form of anatase phase in all the mixed oxides synthesized. The XRD
studies further suggested that titania–zirconia contains an additional (Ti,Zr)O2 phase. UV–Vis DRS results reveal that all samples exhibit absorption maxima near visible region. FTIR results revealed the
presence of Ti–O–Si linkages in the titania–silica sample, which are responsible for its higher activity in the photocatalytic
degradation of phenol under sunlight. 相似文献
19.
H. Khelifi A. Aydi N. Abdelmoula A. Simon A. Maalej H. Khemakhem M. Maglione 《Journal of Materials Science》2012,47(4):1943-1949
Lead-free (1 − x)NaNbO3/xBa(Ti0.5Sn0.5)O3 (x = 0.1, 0.125, 0.15, 0.175, 0.2, and 0.3) ceramics were elaborated by the conventional ceramic technique. Sintering has been
made at 1523 K for 2 h. The crystal structure was investigated by X-ray diffraction with CuKα radiation at room temperature.
As a function of composition, these compounds crystallize with tetragonal or cubic symmetry. Dielectric measurements show
that the materials have a classical ferroelectric behavior for compositions in the range 0.10 ≤ x ≤ 0.15 and relaxor one for compositions in the range 0.15 < x ≤ 0.30. Temperatures T
C or T
m decrease as x content increases. The ferroelectric behavior has been confirmed by hysteresis characterization. For x = 0.1, a piezoelectric coefficient d
31 of 42.146 pC N−1 was obtained at room temperature. The evolution of the Raman spectra was studied as a function of temperature for x = 0.1. 相似文献
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