Influence of oxygen deficiency on the thermoelectric power of Y1Ba2Cu3O7-x

Jha, S R; Reddy, Y. S.; Suri, Dhavala; Kundra, K. D.; Sharma, Richa; Kumar, Deepak

doi:10.1007/bf02879020

Cited by 10 publications

(5 citation statements)

References 15 publications

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“…Report of T c as high as 55 K in oxygen-deficient SmFeAsO 0.85 [57] inspired researchers to continue to look for Fe-based superconductors with still higher T c . Superconductivity was indeed reported in a new material, Fe-Se or referred to as [11] iron-chalcogenide at 8 K by Hsu et al [61]. This compound has a simple structure of Fe-Se layers without intercalating cations, something quite different from the oxypnictides.…”

Section: Superconductivity In Iron-chalcogenides and Mysterious Behavmentioning

confidence: 93%

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High Temperature Cuprate Superconductors and Later Discoveries

Sharma

2015

Superconductivity

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(Bi-2223 with 3 CuO 2 layers). T c thus increases with the number of CuO 2 layers but not beyond three layers. These layered curates have large anisotropy. The superconductivity is strong in the a-b planes (CuO 2 layers) and weak along the c-axis. Critical parameters B c2 and J c too are high in the a-b plane and low along c-direction. Both the materials, Bi-2223 and YBCO are produced commercially and used for selected applications. The new improved 2G-YBCO wires are coated multilayered thin film conductors produced by employing sophisticated techniques and getting popularity among the community. Two more cuprates with still higher T c and analogous to Bi-system were discovered. A T c = 125 in Tl 2 Ca 2 Ba 2 Cu 3 O x (Ti-2223) and 135 K in Hg 1 Ba 2 Ca 2 Cu 3 O 6+δ (Hg-1223) were reported. These materials were, however, not pursued for commercial production because of the toxicity involved. Superconductivity was also found in 2001 in MgB 2 at 39 K, easily attainable with the use of a cryo-cooler. Besides, the material is quite cheap. MgB 2 has two energy gaps and appears to be a BCS superconductor. It is being produced commercially now. The chapter also reviews all the discoveries that took place in 2008 onwards. Hosano reported superconductivity in iron based oxy-pnictides of the type LaFeAsO(1111) around 25 K. T c in excess of 50 K were reported in Sm and Nd based pnictides. The strategy adopted to enhance T c has been to dope the insulating La 2 O 2 layer suitably whereby a charge, electron/hole is transferred to the Fe 2 As 2 conduction layer. Thus a T c = 38 K was reported in a K-doped (Ba 0.6 K 0.4 ) Fe 2 As 2 compound. Very strange behavior of the appearance, disappearance and re-appearance of superconductivity with increasing pressure was announced in an

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Section: Superconductivity In Iron-chalcogenides and Mysterious Behavmentioning

confidence: 93%

“…Our experience shows around 60°C/h. cooling rate is optimum [11]. Fast cooling changes the orthogonal phase into the tetragonal phase and makes the material non superconducting.…”

Section: Methods Of Synthesis Of Ybcomentioning

confidence: 99%

High Temperature Cuprate Superconductors and Later Discoveries

Sharma

2015

Superconductivity

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“…Several reasons and theories to explain this peak have been put forth. While Ma et al (1989), and Trodahl and Mawdsley (1987) attributed it to an enhanced phonon drag effect that truncated at the onset of superconductivity; Jha et al (1989) attributed the anomaly to the pair fluctuation effect. They modified the freeelectron expression for TEP, given by MacDonald et al (1962).…”

Section: Samples With Cuo Added To Yiba2cuz07_~" Ycu Seriesmentioning

confidence: 99%

“…the minimum volume percentage of superconductor in a non-superconducting matrix that shows a zero in the transport property, varies. A zero in TEP could be obtained without getting zero resistance for the electrical conduction (Jha et al 1989;Mammou et al 1994). We pursued this work further, and analysed two series of samples with CuO added respectively to Bil.6Pb0.4SrzCa2-Cu30~ and YIBazCu3OT_,~, for various studies like resistivity, TEP, XRD and SEM.…”

Section: Introductionmentioning

confidence: 99%

Effect of CuO addition in Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O ceramics

Mishra

Dheer

1999

Bull Mater Sci

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The effect of adding CuO matrix to BiF6Pb0.4SrzCa2Cu30 a and YIBa2Cu308 superconductors was investigated through resistivity, XRD, SEM, thermoelectric power (TEP), and ac magnetization studies. Samples with as low as 20% (by weight) of the superconducting phase showed superconducting transition in resistivity-temperature (R-T), with the superconducting zero around 77 K in thermoelectric power, critical current (J~) values were evaluated by applying Bean's critical state model. CuO could be added to the superconducting material without any significant deterioration in the quality of the samples, up to a concentration of as low as 40% (by weight) of the superconducting material.

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“…There has been a great deal of interest in the study of thermopower behaviour of high-T c oxide superconductors in the past three years. For the YBaCuO system, a majority of workers have reported a small and positive thermopower Uher and Kaiser 1987;Henkie et al 1987;Srinivasan et al 1987), although the actual magnitude and temperature dependence are a sensitive function of the oxygen stoichiometry (Hlopkin et al 1988;Jha et al 1989). There has been only one report on the BiSrCaCuO system for the composition BiSrCaCu20 x by Mandal et al (1988), who observed a positive sign with a temperature dependence similar to that of LaSrCuO system.…”

Section: Introductionmentioning

confidence: 99%

Thermopower measurements on BiSrCaCuO system

Bansal

Kumar

1991

Bull. Mater. Sci.

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We report thermoelectric power measurements on BiSrCaCuO (2212) superconducting oxide and compare the observed behaviour with that of the YBaCuO (123) system. The relative importance of phonon drag and diffusion thermopower contributions is evaluated for the two systems by analysing the data using a generalized expression of the type S = aT+ tilT. The thermopower enhancement effect just above T~ gives parameter values comparable to those of YBa2CU3OT_ x system. Keywords. Phonon drag; diffusion thermopower; electron-phonon mass enhancement.

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Influence of oxygen deficiency on the thermoelectric power of Y1Ba2Cu3O7-x

Cited by 10 publications

References 15 publications

High Temperature Cuprate Superconductors and Later Discoveries

High Temperature Cuprate Superconductors and Later Discoveries

Effect of CuO addition in Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O ceramics

Thermopower measurements on BiSrCaCuO system

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