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1.
Chen Zhaojia Liu Hongbao Mao Zhiqiang Wang Keqin Zhan Xiaonong Zhang Yuheng 《Physica C: Superconductivity and its Applications》1988,156(5)
The specific heat anomaly ΔC of Bi1.6Pb0.4Sr2Ca2Cu3Oy was observed in the temperature range 80–100 K. It is estimated from ΔC that γ15 mJ/mol·K2 and Hc2(T=0)100 T in this sample. The specific heat anomaly confirmed the occurrence of bulk superconductivity of the high-Tc phase in Bi1.6Pb0.4Sr2Ca2Cu3Oy superconductor. 相似文献
2.
Effect of incorporation of Sb in place of Bi in the bismuth cuprate superconductors has been examined. The nominal compositions
studied are MCa1·5Sr1·5Cu2O8+δ and MCa2Sr2Cu3O10+δ, whereM=Bi2−x
Sb
x
or Bi1·5−x
Sb
x
Pb0·5. Different preparative routes such as the ceramic method, the matrix route as well as the melt route were employed to prepare
the materials. No indication of either Sb entering the lattice or enhancement ofT
c
is noted from resistivity, magnetic susceptibility and microwave absorption measurements.
Communication No. 162 from Materials Research Centre. 相似文献
3.
High-T
c
superconducting thin films of Bi–Sr–Ca–Cu oxides were prepared by laser-induced plasma deposition of high-T
c
superconducting Bi2Sr2Ca1Cu2Ox and Bi2Sr2Ca2Cu3Ox targets in vacuum and a short post-annealing in air at 875°C. Thin films (thickness <500 nm) with a critical temperatureT
c
-onset of 95 K can be prepared on silicon substrate material with a SrTiO3 interface layer. The thin films were completely superconducting between 80 and 90 K. The stoichiometry transfer of superconducting target material by laser-induced plasma deposition was investigated. 相似文献
4.
M. Weber P. Birrer F. N. Gygax B. Hitti E. Lippelt H. Maletta A. Schenck 《Hyperfine Interactions》1991,63(1-4):93-101
The muon spin relaxation was measured in the high-T
c superconductors Bi2Sr1.3Ca0.7 CuO6.15, Bi2Sr2CaCu2O8 and Bi2Pb
x
Sr2Ca2Cu3O10. We present our method to determine the London penetration depth perpendicular toc-axis λ⊥ (0) taking also contributions from the anisotropic magnetization and nuclear dipoles to the muon frequency spectrum into
account. 相似文献
5.
Yoshitake Nishi Kazuo Nozaki Takuya Kurotaki 《Zeitschrift für Physik B Condensed Matter》1993,91(2):175-178
Influence of Ti addition (substitution for Bi) on Tc is studied for high Tc (Bi1-zTiz)1.6Pb0.4Sr2Ca2Cu3Ox. We found a critical Ti addition to keep high Tc (above 100 K) of the (Bi1-zTiz)1.6Pb0.4Sr2Ca2Cu3Ox. The high-Tc phase can be found up to 0.5 of z. It is explained by an abnormal Tc change which is found from 0.3 to 0.5 of z. Based on results of the electrical resistivity and x-ray diffraction, an abnormal Tc change is discussed. 相似文献
6.
S. Azdad O. Gorochov J. L. Dormann H. Pankowska R. Suryanarayanan S. Sayouri 《Hyperfine Interactions》1992,70(1-4):1167-1170
We report X-ray diffraction, resistivity and Mössbauer studies on several substituted 2201 Bi cuprates, Bi2Sr2Cu1?xFexOy(O≤x≤1) and Bi2Sr1.6La0.4Cu1?xFexOy and Bi1.6Pb0.4Sr1.6La0.4Cu1?xFexOy (O≤x≤0.04). The first series is not superconducting and a new phase appears for x=1. For La substituted samples, Tc increases up to 35K and decreases strongly with x. All Mössbauer spectra were fitted well with four quadrupole doublets, with relative population depending on samples. 相似文献
7.
J. Q. Li C. Chen D. Y. Yang F. H. Li Y. S. Yao Z. Y. Ran W. K. Wang Z. X. Zhao 《Zeitschrift für Physik B Condensed Matter》1989,74(2):165-172
The incommensurate modulated structures of high-T
c superconducting phases Bi2Sr2Ca
n–1Cu
n
O
y
(n=1 and 2) have been studied using symmetry properties of four-dimensional super-spacegroups and electron diffraction as well as high resolution electron microscopy are used to describe the properties of the incommensurate modulated structure in the compounds. The main results are planar monoclinic symmetryP
B
2/b
11 orP
B
b
1 for Bi2Sr2CuO
y
(n=1) and orthorhombic symmetryN
111
Bbmb
orN
111
Bb2b
for Bi2Sr2CaCu2O
y
(n=2). The temperature dependence of the modulated structure of Bi2Sr2CaCu2O
y
has been investigated from –190°C to 800°C. Some structure properties of Bi2Sr2Ca2Cu3O
y
(n=3) are presented for comparison. 相似文献
8.
Haiqian Wang Zhiqiang Mao Ling Zhou Menghua Cheng Guien Zhou Zhaojia Chen 《Applied Physics A: Materials Science & Processing》1990,50(6):519-521
Differently heat-treated samples with the nominal composition Bi1.6Pb0.3Sb0.1Sr2Ca2Cu3O
y
were studied by resistance and ac susceptibility measurements in the temperature range 77 K<T<200 K. The X-ray diffraction patterns at room temperature were also investigated. The experimental results show that repeated quenchings can depress the formation of the 80 K phase, and enhance the formation of the 110 K phase. 相似文献
9.
K. N. Kocharian V. E. Harutunian R. M. Martirossian A. A. Avakian R. Kh. Kamanchajian Kiejin Lee Jaegab Lee Gwangseo Park 《International Journal of Infrared and Millimeter Waves》1991,12(7):749-755
Transmission spectra of Sr2Ca2Cu4Oy, which is a part of high Tc superconducting system Bi2Sr2Can–1CunOz, and their temperature evolutions were investigated by monochromatic quasioptical submillimeter spectroscopy. Strong increase of high frequency conductivity in the range 80 to 350K was revealed. The obtained results were analyzed on basis of thermally activated carriers model. 相似文献
10.
M. I. Petrov D. A. Balaev I. L. Belozerova S. I. Popkov A. A. Dubrovskii K. A. Shaykhutdinov O. N. Mart’yanov 《Technical Physics》2009,54(8):1130-1134
Low-density polycrystalline Bi1.8Pb0.3Sr1.9Ca2Cu3O
x
high-temperature superconductors with a foamlike microstructure and composites consisting of this superconductor and silver
in an amount of 20, 25, and 30 vol % are synthesized. The microstructure, as well as the temperature and field dependences
of the magnetization, M(T) and M(H), are studied. It is found that, in Bi1.8Pb0.3Sr1.9Ca2Cu3O
x
high-temperature superconductors and Bi1.8Pb0.3Sr1.9Ca2Cu3O
x
+ Ag composites, the diamagnetic response is enhanced and the screening properties are improved compared with high-temperature
polycrystalline superconductors with the same composition that are prepared by the standard technology. The observed effect
is explained by the features of magnetic flux penetration into a porous medium. 相似文献
11.
12.
We have investigated the superconducting properties of the Bi1.7 Pb0.3Sr2Ca2−xCe
x
Cu3O10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found
to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate
decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T
c (2 : 2 : 2 : 3) phase decreases and low T
c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition
temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent
state in this system; that is, Ca2+ → Ce4+ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T
c of the system. 相似文献
13.
From isothermalM(H) curves nearT
c
, measured on polycrystalline Tl2Ba2Ca
n–1Cu
n
O2n
+4 and (Bi, Pb)2Sr2Ca
n–1Cu
n
O2n+4 (n=2,3) samples, we deduce the in-plane penetration depths ab as functions of temperature. An estimate according to the BCS weak-coupling clean-limit fit, which produces the data nearT
c
very well, yields ab(0)=3100 Å, 2320 Å 2210 Å, and 1960 Å for Bi2Sr2CaCu2O8, Bi1.6Pb0.4Sr2Ca2Cu3O10, Tl2Ba2CaCu2O8, and Tl2Ba2Ca2Cu3O10, respectively. A comparison between strong-coupling and weak coupling fitting curves clearly favours the weak-coupling temperature dependence of ab nearT
c
. 相似文献
14.
Yu. I. Talanov L. F. Salakhutdinov T. Adachi R. I. Khasanov 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(2):136-138
Excitations of the vortex type in the regions of temperatures both below and above critical temperature T
c are found by studying the local magnetic fields on the surface of Bi2Sr2Ca1 − x
Y
x
Cu2O8 + y
single crystals by means of EPR. The narrow EPR signal of the surface paramagnetic probe allows us to observe weak distortions
of the magnetic field that arise when T > T
c. The behavior of the signal broadening agrees with the hypothesis about the existence of vortices in this temperature region. 相似文献
15.
M. P. Volkov B. T. Melekh V. I. Bakharev N. F. Kartenko N. V. Matykin Yu. N. Filin 《Physics of the Solid State》1999,41(1):15-17
A study has been made of the glass-forming ability, structure, and superconducting properties of Bi2.2Sr1.8Ca1.05Cu2.15LixOy and Bi2.2Sr1.8Ca1.05Cu2.15−x
LixOy (x=0;0.3;0.5;0.7). The compounds were melted by rf at T=1300–1500 °C. Rapid quenching produces glassy alloys whose glass-forming ability is the highest when lithium is substituted
for copper. Glass annealing at 700–800 °C results in the formation of the HTSC phase 2212 with a critical temperature of up
to 91 K. In lithium-doped samples the HTSC phase forms at lower temperatures and shorter anneals and it depends on the cooling
rate following the anneal. The composition and properties of the 2212 phase depend nonmonotonically on the anneal time. The
lattice parameter C of the 2212 phase increases with increasing lithium content.
Fiz. Tverd. Tela (St. Petersburg) 41, 18–21 (January 1999) 相似文献
16.
The thermoelectric power (TEP) for a one-dimensional lattice has been studied using the extended Hubbard model in the limitU ≠ ∞, whereU is the on-site Coulomb interaction. A new expression for TEP has been derived in this study. Our study shows that if theV-dependent term in the extended Hubbard model Hamiltonian is considered as attractive, the new expression for TEP could successfully
reproduce the TEP results of high-T
c hole-doped insulating systems of Tl2Ba2Ca1−x
Y
x
Cu2O8+y
(Tl-2212) and Bi2Sr2Ca−x
Y
x
Cu2O8+y
(Bi-2212). 相似文献
17.
We have studied the electrical and infrared properties of Bi2Sr2Ca1Cu2O8 compound in three states. Electrical and IR measurements show that the pure powder state sample is a semiconductor, the ceramic Bi2Sr2Ca1Cu2O8 sample prepared after annealing at 820°C for 240 hours shows a Tc of 85 K, whereas Bi2Sr2Ca1Cu2O8 sample prepared through glassy route, i.e. melting at 1250°C and annealing at 820°C for 240 hours shows a drop of Tc by 5 K. The infrared spectra of superconducting ceramic and glass ceramic states in the available frequency range of measurement reveals the presence of three phonons. Since the vibrational mode around 595 cm–1 is due to CuO2 layers and as the CuO2 layers are responsible for Tc in the ceramic superconductors, any change in these layers will affect the Tc. The shifting of the 595 cm–1 mode towards lower frequencies in the glass ceramic due to different preparation process, indicates that there is a change in CuO2 layers resulting in a change of Tc, which is confirmed by Four probe dc measurements. 相似文献
18.
Temperature dependence of the critical current in YBa2Cu3O7−δ and Bi2Sr2Ca1Cu2O8 Josephson junctions
B.A. Aminov N.B. Brandt Nguyen Min Thuy Ya.G. Ponomarev M.V. Sudakova A.R. Kaul I.E. Graboi Yu.D. Tretiakov J. Wittig S.P. Kobeleva L.M. Fisher L. Rosta 《Physica C: Superconductivity and its Applications》1989,160(5-6)
We have studied the stationary Josephson effect on YBa2Cu3O7−δ (Tc=90 K) and Bi2Sr2Ca1Cu2 O8 (Tc=80 Kand 87 Kfortwosamplesofdifferentorigin) ceramic based junctions. The temperature dependence of the critical current near Tc has been found as Ic≈(Tc-T)
for the Y-Ba-Cu-O samples indicating that they should be classified as S-N-I-N-S type junctions. The I-V curves of the Bi-Sr-Ca-Cu samples show the typical behaviour of S-I-S structures. Using Ambegaokar-Baratoff's theory for Bi2Sr2Ca1Cu2O8, the temperature dependence of the superconducting state gap Δ(T) was calculated and it was evaluated that 1.452Δ(0)/kBTc3.5. 相似文献
19.
A comprehensive review of structure work on high-T
c
oxides as reported during the years 1987 and 1988 is given. Thirteen structures are refined from X-ray single-crystal and/or neutron powder diffraction data:I. (Ba1–x
,K
x
)BiO3 (T
c
=30 K),II. (La2–x
, Sr
x
)CuO4 (T
c
=40 K),III. (Nd, Ce, Sr)2CuO4 (T
c
=28 K),IV. (Nd2–x
, Ce
x
)CuO4 (T
c
=24 K),V. YBa2Cu3O7 (T
c
=90 K),VI. YBa2Cu4O8 (T
c
=80 K),VII. Y2Ba4Cu7O14 (T
c
=40 K),VIII. Pb2Sr2NdCu3O8 (T
c
=70 K),IX. TlBa2CaCu2O7 (T
c
=103 K),X. TlBa2Ca2Cu3O9 (T
c
=120 K),XI. Tl2Ba2CuO6 (T
c
=90 K),XII. Tl2Ba2CaCu2O8 (T
c
=112 K),XIII. Tl2Ba2Ca2Cu3O10 (T
c
=125 K). Except forI (perovskite type),II (K2NiF4 type) andIV (Nd2CuO4 type) they represent new structure types. Structure data, bond distances, structure drawings and calculated X-ray powder diffraction patterns are given for each compound. Structural features and correlations with superconductivity are discussed. The review contains 301 citations. 相似文献
20.
M. G. Smith R. D. Taylor J. D. Thompson J. O. Willis J. B. Goodenough J. Chan 《Hyperfine Interactions》1994,93(1):1665-1670
The local structure, magnetism, and superconductivity of Y1–z
Ca
z
Sr2Cu3–y
Fe
y
O6+x
have been investigated by magnetic susceptibility,57Fe Mössbauer absorption spectroscopy, X-ray powder diffraction, and iodometric titration. By modification of the hole distribution between the Cu(1)O
x
chains and Cu(2)O2 sheets, we induced bulk superconductivity with a maximum superconducting critical temperatureT
c near 20 K in Y–zCa
z
Sr2Cu2.5Fe0.5O6+x
(0.05z0.18). We interpret the development of a broad maximum inT
c and the Meissner fractionV
f versusz nearz=0.12 to be due to an increasing transfer of holes from the Cu(1)O
x
chains to the Cu(2)O2 sheets induced by a shorterc-axis and reduced Coloumb repulsion of the positively charged Y1–z
Ca
z
plane. The increase in hole transfer from the Cu(1)O
x
chains to the Cu(2)O2 sheets also modulates the magnetic ordering temperatureT
m. We show thatT
m of YSr2Cu2FeO7.26 is approximately 65 K, which is much lower than that observed in YBa2Cu2.31Fe0.69O7.21 (T
m400 K). 相似文献