Preparation and properties of YSr2Cu3−xMxOy (M = Li, Al, Ti, V, Cr, Fe, Co, Ga, Ge, Mo, WandRe)
10 Jun 1992-Physica C-superconductivity and Its Applications (North-Holland)-Vol. 196, Iss: 1, pp 141-152
TL;DR: In this article, the authors investigated the composition YSr2Cu3-xMxOy and obtained the 123-structure for M= Li, Al, Ti, V, Cr, Fe, Co, Ga, Ge, Mo, W and Re.
Abstract: We have investigated the composition YSr2Cu3-xMxOy and obtained the 123-structure for M= Li, Al, Ti, V, Cr, Fe, Co, Ga, Ge, Mo, W and Re. Superconductivity is observed for the compounds with M=Ti, V, Fe, Co, Ga, Ge, Mo, W and Re at low levels of substitution context x. The highest Tzeroc is 73 K for the compound YSr2Cu2.85Re0.15O7.12. Tcs are enhanced by decreasing x or increasing y, which draw the rise of hole concentration pave (Cu2+p). Except for the compounds with M=V and Cr, the structures are tetragonal, while those of the compounds YSr2Cu3-xCrxOy are orthorhombic, and YSr2Cu3-x VxOy shows the structural transition from tetragonal to orthorhombic by HIP treatment with the simultaneous transition from superconductivity to metallic transport property. This Sr-based 123-structure is stabilized by doping elements with ionic radii=0.35-0.49 A or 0.525-0.62 A supposing 4- or 6-coordination, respectively, except for M=Li.
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TL;DR: In this article, the major cuprate materials systems that have laid the foundation of high temperature superconductivity (HTS) science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems.
Abstract: Hole-doped cuprate high temperature superconductors have ushered in the modern era of high temperature superconductivity (HTS) and have continued to be at center stage in the field. Extensive studies have been made, many compounds discovered, voluminous data compiled, numerous models proposed, many review articles written, and various prototype devices made and tested with better performance than their nonsuperconducting counterparts. The field is indeed vast. We have therefore decided to focus on the major cuprate materials systems that have laid the foundation of HTS science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems, while referring readers interested in the HTS physics and devices to the review articles. Developments in the field are mostly presented in chronological order, sometimes with anecdotes, in an attempt to share some of the moments of excitement and despair in the history of HTS with readers, especially the younger ones.
123 citations
TL;DR: A review of the literature on substitutions and their effect on the properties of the 90 K superconductor YBa 2 Cu 3 O δ (YBCO) can be found in this paper.
Abstract: The 90 K superconductor, YBa 2 Cu 3 O δ (YBCO), has proved to be highly adaptable chemically as it can accommodate a wide variety of cationic and anionic substitutions. Indeed, the majority of the chemical elements, excluding noble gases and actinides, have been reported to substitute to some extent into the YBCO structure. This review covers the literature on such substitutions and their effect on the properties of YBCO. Reported solubility limits are given, together with crystal symmetry and trends in unit cell parameters with dopant concentration. The dopant site is considered; this is additionally complex in the case of copper substitution because of the two distinct copper sites in the crystal structure. The effect of the dopant on the critical temperature, T c , is reviewed; the literature is often contradictory due to the dual effects of variable oxygen content and the nature of the dopant. Preparation methods appear to have an effect on solubility limits, crystal symmetry and T c , Also, the methods used to determine solubility limits are often imprecise which can lead to contradictions. The magnetic properties of doped materials are reviewed; for some dopants, particularly the magnetic lanthanides, antiferromagnetism and superconductivity co-exist. The related RBa 2 Cu 3 O δ phases (R = lanthanide), their structure, properties and behaviour on doping are reviewed in a similar way. For the larger rare earths, the related systems R 1+ x Ba 2- x CU 3 O δ , are reviewed; as x increases, the transition temperature decreases and compositions R 1.5 Ba 1.5 Cu 3 O δ are semiconducting. The upper and lower solubility limit changes with R, and for R = Dy, the upper limit is x = 0 composition, LaBa 2 Cu 3 O δ , cannot be prepared in air since substitution of La onto the Ba site occurs, forming the Ba-deficient solid solutions. The discovery of superconductivity above liquid nitrogen temperatures in YBa 2 Cu 3 O 7 , has generated a vast quantity of research; to date, > 20 000 papers have appeared on the 123 materials (source: BIDS). This review, therefore, cannot be comprehensive, but attempts to highlight important substitutions, their effect on the properties of YBCO and any contradictions in the literature.
100 citations
TL;DR: In this paper, a new mercury-based cuprate superconductor, (Hg 1- x Cr x )Sr 2 CuO y (0⩽ x ⩽0.8), having T c of 58 K ( x = 0.3 and 0.4), was synthesized.
Abstract: A new mercury-based cuprate superconductor, (Hg 1- x Cr x )Sr 2 CuO y (0⩽ x ⩽0.8), having T c of 58 K ( x =0.3 has been synthesized. While a chromium-free sample ( x =0) was multi-phased and the superconducting volume fraction was less than 1%, samples for x =0.3 and 0.4 were of nearly single phase and their superconducting shielding volume fraction reached 100% of perfect diamagnetism. X-ray diffraction analysis revealed that its crystal symmetry was tetragonal with lattice parameters a 0 =3.840−3.854 A and c 0 =8.639−8.705 A which slightly varied with x . The observed c 0 value, corresponding to the interlayer distance of superconducting CuO 2 planes, was found to be the shortest among all the known mercury-based “12( n -1) n ” superconductors. Compared to the barium-containing compounds, the present barium-free materials have been found to be insensitive to the ambient air atmosphere during the synthesis and also to be quite stable after storage in air.
82 citations
TL;DR: In this paper, the incorporation of sulphate and phosphate groups into the YBa 2 Cu 3 O 7−δ structure, to form materials such as YSr 2 Cu 2.
Abstract: Following observations that carbonate anions can be substituted into perovskite structures containing Cu to yield superconducting phases, the possibility that other oxy-anions may behave similarly has been explored. Here we report the incorporation of sulphate and phosphate groups into the YBa 2 Cu 3 O 7−δ structure, to form materials such as YSr 2 Cu 2.79 (SO 4 ) 0.21 O 6.16 . The partial replacement of Y 3+ ions by Sr 2+ or Ca 2+ ions injects holes into the CuO 2 layers and results in a change from antiferromagnetic to superconducting behaviour with T c (onset) up to ≈60 K. These materials contain not only new charge reservoir layers but also novel superconducting CuO 2 sheets with both 4-coordinate Cu (as in Nd 2 CuO 4 ) and 5-coordinate Cu (as in YBa 2 Cu 3 O 7 ).
71 citations
TL;DR: The FeSr 2 YCu 2 O 6+δ compound exhibits superconductivity around 50 K only when it is properly annealed in N 2 atmosphere and subsequently in O 2 atmosphere.
Abstract: The FeSr 2 YCu 2 O 6+δ compound with a Ba 2 YCu 3 O 6+δ -type structure exhibits superconductivity around 50 K, only when it is properly annealed in N 2 atmosphere and subsequently in O 2 atmosphere. The compound without N 2 -annealing, however, does not exhibit superconductivity. This compound consists of a sequence of alternating CuO 2 double sheets with nanometer-scale separation as those in high- T c superconductors, and FeO δ sheets similar to that in the SrFeO 3-δ magnetic compound. Neutron diffraction study shows that both N 2 -annealing and subsequent O 2 -annealing cause ordering of Cu and Fe, and that both O 2 -annealing and subsequent oxidization under high-O 2 pressure supply the charge. However, the charge was distributed not only to the CuO 2 sheet but also the FeO δ sheet. The bond valence sum calculation indicates that charges distributed to the FeO δ sheet more than to the CuO 2 sheet in the superconducting sample.
45 citations
References
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TL;DR: The effective ionic radii of Shannon & Prewitt [Acta Cryst. (1969), B25, 925-945] are revised to include more unusual oxidation states and coordinations as mentioned in this paper.
Abstract: The effective ionic radii of Shannon & Prewitt [Acta Cryst. (1969), B25, 925-945] are revised to include more unusual oxidation states and coordinations. Revisions are based on new structural data, empirical bond strength-bond length relationships, and plots of (1) radii vs volume, (2) radii vs coordination number, and (3) radii vs oxidation state. Factors which affect radii additivity are polyhedral distortion, partial occupancy of cation sites, covalence, and metallic character. Mean Nb5+-O and Mo6+-O octahedral distances are linearly dependent on distortion. A decrease in cation occupancy increases mean Li+-O, Na+-O, and Ag+-O distances in a predictable manner. Covalence strongly shortens Fe2+-X, Co2+-X, Ni2+-X, Mn2+-X, Cu+-X, Ag+-X, and M-H- bonds as the electronegativity of X or M decreases. Smaller effects are seen for Zn2+-X, Cd2+-X, In2+-X, pb2+-X, and TI+-X. Bonds with delocalized electrons and therefore metallic character, e.g. Sm-S, V-S, and Re-O, are significantly shorter than similar bonds with localized electrons.
51,997 citations
TL;DR: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure.
Abstract: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure. An estimated upper critical field H c2(0) between 80 and 180 T was obtained.
5,965 citations
IBM1
TL;DR: It is found that T/sub c/ is constant at approx.36 K from p = 0.15 to 0.24, where it begins to decrease, and beyond papprox. =0.32, superconductivity disappears, even though the samples are more conducting.
Abstract: Samples of ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4\ensuremath{-}\ensuremath{\delta}}$ have previously shown a maximum concentration of $p=0.15$ holes per [Cu${\mathrm{O}}_{2}$] unit, because increasing $xg0.15$ normally induces compensating oxygen vacancies. Annealing samples in 100 bars of oxygen pressure fills the oxygen vacancies and greatly increases the range of accessible hole concentrations, up to $p=0.40$ (or effectively ${\mathrm{Cu}}^{+2.40}$). We find that ${T}_{c}$ is constant at \ensuremath{\simeq}36 K from $p=0.15 \mathrm{to} 0.24$, where it begins to decrease. Beyond $p\ensuremath{\simeq}0.32$, superconductivity disappears, even though the samples are more conducting.
694 citations
IBM1
TL;DR: These data are interpreted to demonstrate that the (Cu-O) charge in the sheets largely determines T/sub c/ and that the varying oxygen content and the chains merely provide an insulating reservoir of charge.
Abstract: A series of new $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{y}$-like materials are reported in which the oxygen content and the average [Cu-O] charge (or Cu valence) are separately varied over a wide range. We find a distinct boundary between samples showing anomalous insulating behavior and those with high ${T}_{c}$. These data are interpreted to demonstrate that the [Cu-O] charge in the sheets largely determines ${T}_{c}$ and that the variable oxygen content and the chains merely provide an insulating reservoir of charge.
467 citations
TL;DR: In this article, the superconductivity close to the boiling point of liquid nitrogen has been discovered in the P-Sr-R-Ca-Cu-O system where R is Y or rare earth.
Abstract: Superconductivity close to the boiling point of liquid nitrogen has been discovered in the P-Sr-R-Ca-Cu-O system where R is Y or rare earth. The superconducting compound has been identified as Pb 2 Sr 2 (R,Ca) 1 Cu 3 O 8+ y and the structure of the R=Y compound has been solved by single-crystal X-ray diffraction methods. The structure consists of double CuO 2 sheets interleaved by (Ca,R), a unit which is common to most of the high- T c copper oxide superconductors. A new structural feature found in this system is a double PbO layer separated by a sheet of copper atoms. A non-superconducting oxide of approximate composition (Y,Ca)Sr 2 (Cu,Pb) 3 O 7− y formed as a second phase in some preparations has been also characterized; its structure is related YBa 2 Cu 3 O 7 .
198 citations