59 research outputs found
Superconducting And Magnetic Behaviour Of Niobium Doped Rusr 2gd1.5ce0.5cu2o10-δ
No full textPolycrystalline samples of Ru1-xNbxSr 2Gd1.5Ce0.5Cu2O 10-δ, 0≤x≤0.5, have been synthesized and structurally characterized by x-ray diffraction (XRD). Resistivity, magnetization and AC susceptibility measurements have been done and analysed considering a phase separation scenario. A strong suppression of the cluster glass (CG) transition associated with niobium doping was identified. In fact, the CG phase was not present in samples for x≥0.2, leading to changes in the magnetic hysteresis loops measured at low temperatures. These hysteresis loops can be explained as a result of the contribution of two distinct magnetic phases: the canted AFM phase and embedded Ru4+-rich clusters which order as a CG in low temperatures. Interestingly, the significant changes in the magnetic response of the material do affect the superconducting transition temperature T c. It was found that both Tc and the superconducting fraction are reduced in samples which present the spin glass phase. Therefore, our results point to some coupling between magnetism and superconductivity in this ruthenocuprate family, the presence of the magnetic moment being deleterious for the superconductivity. © 2007 IOP Publishing Ltd.1918Felner, I., Asaf, U., Levi, Y., Millo, O., (1997) Phys. Rev., 55 (6), p. 3374Tokunaga, Y., Kotegawa, H., Ishida, K., Kitaoka, Y., Takagiwa, H., Akimitsu, J., (2001) Phys. Rev. Lett., 86 (25), p. 5767Awana, V.P.S., Karppinen, M., Yamauchi, H., (2003) Studies of High Tc Superconductors, p. 77Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Takayama-Muromachi, E., De Lima, O.F., Yamauchi, H., Karppinen, H., (2003) Phys. Rev., 67, pp. 020407RCardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Kishan, H., Takayama-Muromachi, E., De Lima, O.F., (2004) Physica, 405 (3-4), p. 212Cardoso, C.A., Lanfredi, A.J.C., Chiquito, A.J., Araujo-Moreira, F.M., Awana, V.P.S., Kishan, H., De Almeida, R.L., De Lima, O.F., (2005) Phys. Rev., 71 (13), p. 134509Felner, I., Galstyan, E., Herber, R.H., Nowik, I., (2004) Phys. Rev., 70, p. 094504Shengelaya, A., Khasanov, R., Eschenko, D.G., Felner, I., Asaf, U., Savić, I.M., Keller, H., Müller, K.A., (2004) Phys. Rev., 69, p. 024517Xue, Y.Y., Cao, D.H., Lorenz, B., Chu, C.W., (2001) Phys. Rev., 65, pp. 020511RFelner, I., Galstyan, E., Nowik, I., (2005) Phys. Rev., 71, p. 064510Garcia, S., Ghivelder, L., Soriano, S., Felner, I., (2006) Eur. Phys. J., 53 (3), p. 307Lopez, A., Azevedo, I.S., Gonzalez, J.L., Baggio-Saitovitch, E., Micklitz, H., (2006) Physica, 442 (1), p. 33Matvejeff, M., Awana, V.P.S., Jang, L.-Y., Liu, R.S., Yamauchi, H., Karppinen, M., (2003) Physica, 392, p. 87Ivković, I., Hirai, Y., Frazer, B.H., Prester, M., Drobac, D., Ariosa, D., Berger, H., Onellion, M., (2002) Phys. Rev., 65 (14), p. 144420Fainstein, A., Winkler, E., Butera, A., Tallon, J., (1999) Phys. Rev., 60 (18), p. 12597Williams, G.V.M., Krämer, S., (2000) Phys. Rev., 62 (6), p. 4132Butera, A., Fainstein, A., Winkler, E., Tallon, J., (2001) Phys. Rev., 63 (5), p. 054442Felner, I., Galstyan, E., (2003) Int. J. Mod. Phys., 17 (18-20), p. 3617Shi, L., Li, G., Feng, S.J., Li, X.-G., (2003) Phys. Status Solidi, 198 (1), p. 137Shi, L., Li, G., Pu, Y., Zhang, X.D., Feng, S.J., Li, X.-G., (2003) Mater. Lett., 57 (24-25), p. 3919Lee, H.K., Park, H.M., Williams, G.V.M., (2005) Int. J. Mod. Phys., 19 (1-3), p. 353Awana, V.P.S., Lal, R., Kishan, H., Narlikar, A.V., Peurla, M., Laiho, R., (2006) Phys. Rev., 73, p. 014517Awana, V.P.S., Kishan, H., Eshkenazi, O., Felner, I., Rawat, R., Ganesan, V., Narlikar, A.V., (2007) J. Phys.: Condens. Matter, 19 (2), p. 026203Kalavathi, S., Janaki, J., Sairam, T.N., Maui, A., Rawat, R., Sastry, V.S., (2006) Solid State Commun., 139 (7), p. 334Goh, S.K., Williams, G.V.M., Lee, H.K., (2006) Curr. Appl. Phys., 6 (3), p. 515Lee, H.K., Kim, Y.C., (2003) Int. J. Mod. Phys., 17 (18-20), p. 3682Lee, H.K., Williams, G.V.M., (2004) Physica, 415 (4), p. 172Rijssenbeek, J.T., Mansourian-Hadavi, N., Malo, S., Ko, D., Washburn, C., Maignan, A., Pelloquin, D., Poeppelmeier, K.R., (2000) Physica, 341-348, p. 481Williams, G.V.M., Lee, H.K., Krämer, S., (2003) Phys. Rev., 67, p. 104514McLaughlin, A.C., Janowitz, V., McAllister, J.A., Attfield, J.P., (2000) Chem. Commun., 14 (14), p. 1331Liu, R.S., Jang, L.-Y., Hung, H.-H., Tallon, J.L., (2001) Phys. Rev., 63 (21), p. 212505Williams, G.V.M., Jang, L.-Y., Liu, R.S., (2002) Phys. Rev., 65, p. 64508Hu, Z., Von Lips, H., Golden, M.S., Fink, J., Kaindl, J., De Groot, F.M.F., Ebbinghaus, S., Reller, A., (2000) Phys. Rev., 61 (8), p. 5262Goldfarb, R.B., Lelental, M., Thompson, C.A., (1991) Susceptibility of Superconductors and Others Spin Systems, p. 4
Magnetic And Superconducting Properties Of Ru Sr2 Gd1.5 Ce0.5 Cu2 O10-δ Samples: Dependence On The Oxygen Content And Aging Effects
No full textThe magnetic and superconducting properties of Ru Sr2 Gd1.5 Ce0.5 Cu2 O10-δ polycrystalline samples with different oxygen-doping levels are presented. A strong suppression of the superconducting temperature (Tc), as well as a reduction in the superconducting fraction, occurs as the oxygen content is reduced by annealing the samples in oxygen-deprived atmospheres. Drastic changes in the electrical resistivity are observed above Tc, possibly associated with oxygen removal, mainly from grain boundaries. However, the magnetic ordering is relatively less affected by the changes in oxygen content of the samples. The spin-glass transition is enhanced and shifted to higher temperatures with the reduction in oxygen content. This could be correlated with an increase in the spin disorder and frustration for the oxygen-depleted samples. Also, the same oxygen-vacancy-induced disorder could explain the reduction in the fraction of the sample showing antiferromagnetic order. We also report significant changes in the measured properties of the samples as a function of time. © 2005 The American Physical Society.7113Felner, I., Asaf, U., Levi, Y., Millo, O., (1997) Phys. Rev. B, 55, p. 3374. , PRBMDO 0163-1829 10.1103/PhysRevB.55.R3374Bernhard, C., Tallon, J.L., Niedermayer, Ch., Blasius, Th., Golnik, A., Brücher, E., Kremer, R.K., Ansaldo, E.J., (1999) Phys. Rev. B, 59, p. 14099. , PRBMDO. 0163-1829. 10.1103/PhysRevB.59.14099Awana, V.P.S., Karppinen, M., Yamauchi, H., (2003) Studies of High Tc Superconductors, 46, p. 77. , edited by A. V. Narlikar (Nova Science Publishers, New YorkMatvejeff, M., Awana, V.P.S., Jang, L.-Y., Liu, R.S., Yamauchi, H., Karppinen, M., (2003) Physica C, 392-396, p. 87. , PHYCE6 0921-4534Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Kishan, H., Takayama-Muromachi, E., De Lima, O.F., (2004) Physica C, 405, p. 212. , PHYCE6 0921-4534Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Takayama-Muromachi, E., De Lima, O.F., Yamauchi, H., Karppinen, M., (2003) Phys. Rev. B, 67, p. 020407. , PRBMDO 0163-1829 10.1103/PhysRevB.67.020407Shi, L., Li, G., Fan, X.J., Feng, S.J., Li, X.-G., (2003) Physica C, 399, p. 69. , PHYCE6 0921-4534Felner, I., Asaf, U., Ritter, F., Klamut, P.W., Dabrowski, B., (2001) Physica C, 364-365, p. 368. , PHYCE6 0921-4534Felner, I., Asaf, U., Galstyan, E., (2002) Phys. Rev. B, 66, p. 024503. , PRBMDO 0163-1829 10.1103/PhysRevB.66.024503Felner, I., Asaf, U., Levi, Y., Millo, O., (2000) Physica C, 334, p. 141. , PHYCE6 0921-4534 10.1016/S0921-4534(00)00250-1Awana, V.P.S., Ansari, M.A., Gupta, A., Saxena, R.B., Kishan, H., Buddhikot, D., Malik, S.K., (2004) Phys. Rev. B, 70, p. 104520. , PRBMDO 0163-1829 10.1103/PhysRevB.70.104520Yoshizawa, H., Mitsuda, S., Aruga, H., Ito, A., (1987) Phys. Rev. Lett., 59, p. 2364. , PRLTAO 0031-9007 10.1103/PhysRevLett.59.2364Binder, K., Young, A.P., (1986) Rev. Mod. Phys., 58, p. 801. , RMPHAT 0034-6861 10.1103/RevModPhys.58.801Mydosh, J.A., (1993) Spin Glasses An Experimental Introduction, , Taylor & Francis, LondonFelner, I., Galstyan, E., Herber, R.H., Nowik, I., (2004) Phys. Rev. B, 70, p. 094504. , PRBMDO 0163-1829 10.1103/PhysRevB.70.094504Shengelaya, A., Khasanov, R., Eschenko, D.G., Felner, I., Asaf, U., Savić, I.M., Keller, H., Müller, K.A., (2004) Phys. Rev. B, 69, p. 024517. , PRBMDO. 0163-1829. 10.1103/PhysRevB.69.024517Xue, Y.Y., Cao, D.H., Lorenz, B., Chu, C.W., (2002) Phys. Rev. B, 65, p. 020511. , PRBMDO 0163-1829 10.1103/PhysRevB.65.02051
Study Of The Superconducting And Magnetic Properties Of Niobium Doped Rusr2gd1.5ce0.5cu2o10-δ Ruthenocuprates
No full textPolycrystalline samples of Ru1-xNbxSr2Gd1.5Ce0.5Cu2O10-δ, 0 ≤ x ≤ 0.5, have been synthesized and studied by resistivity, magnetization and ac susceptibility measurements. It was identified a strong suppression of the spin glass (SG) transition, which was totally suppressed in samples for x ≥ 0.2. The hysteresis loops at low temperatures are the result of the contribution of two distinct magnetic phases: a canted AFM phase and the SG phase. More importantly, the significant changes in the magnetic response of the material affect the superconducting properties of the samples. It was found that both Tc and the superconducting fraction are reduced in samples that show the spin glass phase, possibly due to the magnetic pair breaking effect. © 2007 Elsevier B.V. All rights reserved.460-462 ISPEC. ISS.442443Cardoso, C.A., Araujo-Moreira, F.M., Awana, V.P.S., Takayama-Muromachi, E., de Lima, O.F., Yamauchi, H., Karppinen, M., (2003) Phys. Rev. B, 67, p. 020407Lee, H.K., Kim, Y.C., (2003) Int. J. Mod. Phys. B, 17, p. 3682Lee, H.K., Williams, G.V.M., (2004) Physica C, 415, p. 17
Neutron Diffraction On Er1-xcaxba2cu3o7-δ (0.0≤x≤0.3) System: Possible Oxygen Vacancies In Cu-o2 Planes
No full textIn the system Er1-xCaxBa2Cu3O7-δ with x = 0.0 to 0.3, the superconducting transition temperature (Tc), as measured from AC susceptibility, decreases with increasing Ca substitution, x. Detailed analysis of the powder neutron diffraction patterns of these samples shows a decrease in oxygen content with increasing x. The orthorhombic distortion decreases slightly and the c-parameter increases slightly with increasing x. Both, the buckling angle [(Cu(2)-O(2)-Cu(2) angle)] and the planer Cu(2)-O(2) distance in Cu-O2 planes, increase with increasing x. Increased Cu(2)-O(2) bond distance indicates a slight decrease in p-type hole carriers in Cu-O2 planes. On comparison with reported results on Tc vs. p-type carriers in high Tc superconducting compounds, it is inferred that decrease in p-type carriers alone cannot account for sharp Tc depression with increasing x in Er1-xCaxBa2Cu3O7-δ system. With increasing x, oxygen vacancies are created in Cu-O2 planes, which along with increased buckling angle might be partly responsible for Tc suppression in this system.3383197204Cava, R.J., Batlogg, B., Chen, C.H., Rietman, E.A., Zharuk, S.M., Werder, D., (1987) Nature (London), 329, p. 429Tranquada, J.M., Mouden, A.H., Goldman, A.I., Zolliker, P., Cox, D.E., Shrine, G., Sinha, S.K., Jocobson, A.J., (1988) Phys. Rev. B, 38, p. 2477Matsuda, A., Kinoshita, K., Ishii, T., Shibate, H., Watanabe, T., Yamada, Y., (1988) Phys. Rev. B, 38, p. 2910McCarron E.M. III, Crawford, M.K., Parise, J.B., (1994) J. Solid State Chem., 78, p. 192Awana, V.P.S., Tulapurkar, A., Malik, S.K., Narlikar, A.V., (1994) Phys. Rev. B, 50, p. 594Awana, V.P.S., Malik, S.K., Yelon, W.B., (1996) Physica C, 262, p. 272Manthiram, A., Lee, S.J., Goodenough, J.B., (1989) J. Solid State Chem., 73, p. 278Manthiram, A., Goodenough, J.B., (1989) Physica C, 159, p. 760Kontos, A.G., Dupree, R., Han, Z.P., (1995) Physica C, 247, p. 1Kulkarni, R.G., Raibagker, R.L., Bichile, G.K., Shaikh, A., Bhalodia, J.A., Baidha, G.J., Kuberkar, D.G., (1993) Supercond. Sci. Technol., 6, p. 678Awana, V.P.S., Narlikar, A.V., (1994) Phys. Rev. B, 49, p. 6353Awana, V.P.S., Malik, S.K., Yelon, W.B., (1996) Mod. Phys. Lett. B, 10, p. 845Sedky, A., Gupta, A., Awana, V.P.S., Narlikar, A.V., (1998) Phys. Rev. B, 58, p. 12495Tarascon, J.M., Bagley, B.G., (1993) Chemistry of High Temperature Superconductors, p. 310. , T.A. Vanderaha. New York: Noyes PublishersWhangbo, H., Torardi, C.C., (1990) Science, 249, p. 1143Whangbo, M.H., Torardi, C.C., (1988) Physica C, 152, p. 251Wu, M.K., Asburn, J.R., Torng, C.J., Hor, P.H., Meng, R.L., Gao, L., Huang, Z.J., Chu, C.W., (1987) Phys. Rev. Lett., 58, p. 908Chmaissem, O., Jorgensen, J.D., Short, S., Knizhnik, A., Eckstein, Y., Shaked, H., (1999) Nature, 397, p. 45Awana, V.P.S., Narlikar, A.V., (1993) Phys. Rev. Lett., 71, p. 303Bernhard, C., Tallon, J.L., (1996) Phys. Rev. B, 54, p. 10201Awana, V.P.S., Moorthy, V.N., Narlikar, A.V., (1994) Phys. Rev. B, 49, p. 6385Nakane, T., Fujinami, K., Karppinen, M., Yamauchi, H., (1999) Supercond. Sci. Technol., 12, p. 24
Suppression of superconductivity with Pr substitution in Nd1-xPrxBaCaCu3O7 system
No full textThe structural, superconducting and magnetic properties of Nd1-xPrxBaCaCu3O7 system with x = 0.0, 0.10, 0.25, 0.35, 0.50, 0.75 and 1.0 have been investigated. X-ray diffraction results reveal that Pr substitutes isostructurally in NdBaCaCu3O7 (Nd:1113) superconductor with complete solubility. The superconducting transition temperature (T-c), measured by ac susceptibility technique, decreases with increasing x. However, suppression of T-c with increasing Pr substitution is less in Nd:1113 superconductor compared to that reported for Nd1-xPrxBa2Cu3O7 system. Interestingly, in the fully Pr substituted compounds of the above series, i.e., in PrBaCaCu3O7 and PrBaxCu3O7, the Pr moments order antiferromagnetically with T-N of 10 and 17 K, respectively. The present results along those reported earlier [V.P.S. Awana, J. Horvat, S.X. Dou, A. Sedky, A.V. Narlikar, J. Magn. Magn. Mater., 182 (1998) L280; V.P.S. Awana, S.X. Dou, S.K. Malik, Rajvir Singh, A.V. Narlikar, D.A. Landinez Tellez, J.M. Ferreira, J. Albino Aguiar, S. Uma, E. Gmelin, W.B. Yelon, J. Magn. Magn. Mater., 187 (1998) 192], clearly suggest that there is a correlation between the T-c suppression due to Pr and the magnetic ordering temperature of the fully substituted Pr moments in these systems. The T-N may be taken to be a measure of the strength of hybridization between the Pr-4f electrons with Cu-O conduction band, and hence a lower T-N may imply a less deleterious effect on superconductivity. (C) 1999 Elsevier Science B.V. All rights reserved.3164167111311
Strong Dependence Of Superconducting Transition Temperature (t(c)) On The Rare Earth Ionic Size In Rebasrcu3o7 (re = Y, Dy, Nd And La) Series
No full textThe REBaSrCu3O7 compounds with RE = Y, Dy, Nd and La have been synthesized by the standard solid-state reaction route. Superconducting transition temperatures (T(c)), as measured by ac susceptibility technique, are 81 K, 79 K, 62 K and 45 K for samples with RE = Y, Dy, Nd and La, respectively. The rare earth dependence of T(c) in the REBaSrCu3O7 series is quite different from that observed in the REBa2Cu3O7 (RE:123) series where T(c) is nearly independent of the choice of the RE (except when RE = Ce, Pr and Tb). Neutron diffraction studies have been carried out on the REBaSrCu3O7 compounds and structural details have been obtained from the Rietveld analysis of the room-temperature neutron diffraction data. The compounds with RE = Y, Dy are found to crystallize in the orthorhombic RE:123 structure (space group Pmmm) with orthorhombicity considerably smaller than that of the RE:123 compounds. In fact, the orthorhombicity reduces so much that the REBaSrCu3O7 compounds with light rare earths, RE = La and Nd, are tetragonal or almost tetragonal.1410361372Oesterreicher, H., Smith, M., (1987) Mater. Res. Bull., 22, p. 1709Soderholm, L., Zhang, K., Hinks, D.G., Beno, M.A., Jorgensen, J.D., Segre, C.U., Schuller, I.K., (1987) Nature, 328, p. 604Herrmann, J., Boehnke, U.-C., Krotzsch, M., Lippold, B., (1994) Physica, 221 C, p. 76Kebede, A., Jee, C.-S., Schwegler, J., Crow, J.E., Mihalisin, T., Myer, G.H., Salomon, R.E., Guertin, R.P., (1989) Phys. Rev., 40 B, p. 4453Malik, S.K., Tomy, C.V., (1994), p. 283. , Physical and Material Properties of High Temperature Superconductors, eds. S. K. Malik and S. S. Shah (Nova Science, New York)Agarwal, S.K., Lal, R., Awana, V.P.S., Pandey, S.P., Narlikar, A.V., (1994) Phys. Rev., 50 B, p. 10265Buckley, R.G., Tallon, J.L., Pooke, D.M., Presland, M.R., (1990) Physica, 165 C, p. 391Xu, Y.H., Guan, W.Y., (1992) Phys. Rev., 45 B, p. 3176Malik, S.K., Tomy, C.V., Bhargava, P., (1991) Phys. Rev., 44 B, p. 7042Ata-Allah, S.S., Xu, Y.H., Heiden, Ch., (1994) Physica, 221 C, p. 39Singh, R., Narlikar, A.V., Awana, V.P.S., Horvat, J., Dou, S.X., (1998) Physica, 301 C, p. 48Fu, W.T., Zandbergen, H.W., Vander Beek, C.J., De Jongh, L.J., (1988) Physica, 156 C, p. 133Peng, J.L., Klavins, P., Shelton, R.N., Radousky, H.B., Hahn, P.A., Bernardez, L., Costantino, M., (1989) Phys. Rev., 39 B, p. 9074Awana, V.P.S., De Lima, O.F., Malik, S.K., Yelon, W.B., Narlikar, A.V., (1999) Physica, 314 C, p. 93Mitros, C., Psycharis, V., Koufoudalis, A., Gamri-Seale, H., Niarchos, D., (1990) J. Less-Common Mat., 164-165, p. 892Das, A., Suryanarayanan, R., (1995) J. Physique, 15, p. 623Liang, J.M., Chang, L., Sung, H.M., Wu, P.T., Chen, L.J., (1988) J. Appl. Phys., 64, p. 3593Awana, V.P.S., Malik, S.K., Yelon, W.B., (1996) Physica, 262 C, p. 272Wang, X.Z., Hellerbrand, B., Bauerele, D., (1992) Physica, 200 C, p. 12Badri, V., Varadaraju, U., Subba Rao, G.V., Physical and Material Properties of High Temperature Superconductors, eds. S. K. Malik and S. S. Shah (Nova Science, New York), to be publishedSuryanarayanan, R., Nafidi, A., Das, A., (1994) J. Appl. Phys., 76, p. 598Zhang, H., Sato, H., (1993) Phys. Rev. Lett., 70, p. 1693Awana, V.P.S., Narlikar, A.V., (1993) Phys. Rev. Lett., 71, p. 303Goldshmidt, D., Direkovitch, Y., Knizhnik, A., Eckestein, Y., (1993) Phys. Rev. Lett., 71, p. 3392Saked, H., Veal, B.W., Faber, J., Hitterman, R.L., Balachandran, U., Tomlins, G., Shi, H., Paulikas, A.P., (1990) Phys. Rev., 41 B, p. 4173Lindemer, T.B., Chakoumakos, B.C., Specht, E.D., Williams, R.K., Chen, Y.J., (1994) Physica, 231 C, p. 80Williams, G.V.M., Tallon, J.L., (1996) Physica, 258 C, p. 41Henkie, Z., Cichorek, T., Drulis, H., Klamut, J., (1993) Physica, 214 C, p. 138Hor, P.H., Meng, R.L., Wang, Y.Q., Gao, La., Huang, Z.J., Bechtold, J., Foster, K., Chu, C.W., (1987) Phys. Rev. Lett., 58, p. 1891Kramer, M.J., Yoo, S.I., Callum, R.W., Yelon, W.B., Xie, H., Allenspach, P., (1994) Physica, 219 C, p. 145Narlikar, A.V., Agarwal, S.K., Narsimha Rao, C.V., (1989), p. 343. , Studies of High Temperature Superconductors, ed. A. Narlikar (NOVA Science Pubs., New York)Morris, D.E., Nickel, J.H., Wei, J.Y.T., Asmar, N.G., Scott, J.S., Scheven, U.M., Hultgren, C.T., Hazen, R.M., (1989) Phys. Rev., 39 B, p. 7347Chen, T.-M., Lai, Y.-L., Kao, F.S., (1997) Physica, 282-287 C, p. 789Shannon, R.D., (1976) Acta Cryst., 32 A, p. 751Tarascon, J.M., Bagley, B.G., (1993), p. 310. , Chemistry of High Temperature Superconductors, ed. T. A. Vanderah (NOYES Publishers, New York)Okai, B., (1990) Jpn. J. Appl. Phys., 129, pp. L218
Hole doping into Co-12s2 copper oxides with s fluorite-structured layers between CuO2 planespiezolaminated composite plate
No full textIn this work, the first three members (s ¼ 1, 2, 3) of the Co-12s2 homologous series of multi-layered copper oxides are gradually doped
with holes through high-pressure oxygenation (HPO). The phases differ from each other only by thickness of the fluorite-structured layer
block, (Ce,Y,Ca)–[O2–(Ce,Y)]s1, between two identical CuO2 planes. High-resolution transmission-electron microscopy (HRTEM) and
electron diffraction (ED) analyses together with both synchrotron X-ray and neutron powder diffraction data, reveal that as a
consequence of HPO the charge-reservoir CoO4-tetrahedra chains get broken and the lattice symmetry of the Co-12s2 phases changes
from orthorhombic to tetragonal. Oxygen contents are analyzed for the samples with wet-chemical and thermogravimetric techniques.
The valence state of copper in the CuO2 plane is determined from Cu L-edge X-ray absorption near-edge structure (XANES) spectra to
be compared with the values estimated through bond-valence-sum (BVS) calculations from the crystal structure data. The positive charge
induced by oxygen loading (or aliovalent CaII-for-YIII substitution in CoSr2YCu2O7+d) is found not to be completely accommodated in
the CuO2 planes but be rather effectively trapped at the charge-reservoir Co atoms. Superconductivity appears in the Co-1212
(CoSr2YCu2O7+d) samples with the copper valence of 2.13 or higher, whereas in the Co-1222 (CoSr2(Ce0.25Y0.75)2Cu2O9+d) and Co-
1232 (CoSr2(Ce0.67Y0.33)3Cu2O11+d) samples Cu valence does not increase high enough to induce superconductivity
Structural Studies On Er1-xcaxba2cu3o7-δ: Oxygen Vacancies In Cu - O2 Planes
No full textIn the Er1-xCaxBa2Cu3O7-δ system, with x = 0.0 to 0.3, the superconducting transition temperature (Tc), as measured from ac susceptibility, decreases with increasing Ca substitution, x. Detailed analysis of the powder neutron diffraction patterns of these samples shows a decrease in oxygen content with increasing x. The orthorhombic distortion decreases slightly and the c-parameter increases with increasing x. Both, the buckling [Cu(2)-O(2)-Cu(2)] angle and the planar Cu(2)-O(2) distance in Cu-O2 planes increase with increasing x. Increased Cu(2)-O(2) bond distance indicates a slight decrease in p-type hole carriers in Cu-O2 planes. With increasing x, oxygen vacancies are created in Cu-O2 planes, which along with increased buckling angle, may be partly responsible for Tc suppression in this system. © 2000 Elsevier Science B.V All rights reserved.341-348PART 1557558McCarron, I.E.M., (1994) J. Solid Sate Chem., 78, p. 192Awana, V.P.S., (1994) Phys. Rev. B, 50, p. 594Manthiram, A., (1889) Physica C, 159, p. 760Awana, V.P.S., (1996) Physica C, 262, p. 272(1996) Mod. Phys. Lett. B, 10, p. 845Sedky, A., (1998) Phys. Rev. B, 58, p. 1249
Structural And Superconducting Properties Of Labacacu3o7+δ System: A Neutron Diffraction Study
No full textThe results on structural aspects and superconductivity of LaBaCaCu3O7+δ (La:1113) are reported. Both X-ray and neutron diffraction studies have been carried out on this compound which reveal that this compound crystallizes in the tetragonal structure (space group P4/mmm). Detailed analysis of the neutron diffraction data reveals that the Ca, Ba and La atoms in this compound are intermixed at the nominal La and Ba sites. Nearly 46% of Ca occupy the usual La-site, while the remaining 54% occupies the Ba-site. Consequently, a corresponding amount of La substitutes at the Ba-site. The intermixing of Ca, Ba and La sites randomizes the chain site oxygens leading to a tetragonal structure for this compound despite an oxygen content close to 7. These occupancy refinements explain the tetragonal structure of the compound, despite having an oxygen content close to 7.04. The compound studied presently shows a sharp superconducting transition at about 68 K.31419397Oesterreider, H., Smith, M., (1987) Mater. Res. Bull., 22, p. 1709Soderholm, Zhang, K., Hinks, D.G., Beno, M.A., Jorgensen, J.D., Segre, C.U., Schuller, I.K., (1987) Nature, 328, p. 604Hermann, Boehnke, U.-C., Kortzsch, M., Lippold, B., Schlenkrich, F., (1994) Physica C, 221, p. 76Kebede, Jee, C.-S., Schwegler, J., Crow, J.E., Mihalisin, T., Myer, G.H., Salomon, R.E., Guertin, R.P., (1989) Phys. Rev. B, 40, p. 4453Malik, S.K., Tomy, C.V., (1994) Physical and Material Properties of High Temperature Superconductors, p. 283. , in: S.K. Malik, S.S. Shah (Eds.), Nova Science, New YorkAwana, V.P.S., Horvat, J., Dou, S.X., Singh, R., Narlikar, A.V., (1998) Physica C, 301, p. 48Fu, W.T., Zandbergen, H.W., Vander Beek, C.J., De Jongh, L.J., (1988) Physica C, 156, p. 133Peng, J.L., Kalvins, P., Shelton, R.N., Radousky, H.B., Hahn, P.A., Bernardez, L., Costantino, M., (1989) Phys. Rev. B, 39, p. 9074Awana, V.P.S., Malik, S.K., Yelon, W.B., (1996) Physica C, 262, p. 272Leu, Y.D., Huang, W.N., Wang, C.M., Kao, H.-C.I., (1996) Physica C, 261, p. 284Yagi, T., Domon, M., Okajima, Y., Yamaya, T., (1991) Physica C, 173, p. 453Tarascon, J.M., Bagley, B.G., (1993) Chemistry of High Temperature Superconductors, p. 310. , in: T.A. Vanderah (Ed.), Noyes Publishers, New YorkAwana, V.P.S., Malik, S.K., Yelon, W.B., (1996) Mod. Phys. Lett. B, 10, p. 845De Leeuw, Mutsaers, C.A.H.A., Van Hal, H.A.M., Verweij, H., Carim, A.H., Smoorenberg, H.C.A., (1988) Physica C, 156, p. 126Zandbergen, Fu, W.T., De Jongh, L.J., (1988) Physica C, 156, p. 30
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