Structural aspects and superconductivity in oxygen-deficient Y1−xCaxBa2Cu3O7−y (y ≈ 0.3) system A neutron-diffraction study

Awana, V. P. S.; Malik, S.K.; Yelon, W. B.

doi:10.1016/0921-4534(96)00213-4

Cited by 55 publications

(34 citation statements)

References 15 publications

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“…Thus Tables 2 and 3]. Similar pattern is also observed in earlier studies [17,20,21]. The increase in Cu 2 - The mechanism of hole doping can be understood in terms of effective oxygen coordination of Cu 2 atoms.…”

Section: Resultssupporting

confidence: 78%

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Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Singh

Husain

Awana

2012

J Supercond Nov Magn

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Here we study the effect of Ca doping on the charge-transfer mechanism of polycrystalline YBa 2 Cu 3 O 7−δ compound. The samples of composition Y 1−x Ca x Ba 2 Cu 3 O 7−δ (x = 0.00, 0.05, 0.10, 0.20 and 0.30) are synthesized through standard solid-state reaction route. Carrier doping is controlled by annealing of samples in oxygen and subsequently in reducing atmosphere. Samples are investigated using resistivity, dc magnetization (M-T ) and magnetization with field (M-H ) measurements. With increase of Ca the transition temperature (T c ) decreases in oxygenated samples, whereas the same increases in reduced samples. Further reduction of samples at higher temperatures (>600°C) though results in non-superconducting nature up to Ca concentration of x = 0.20, the x = 0.30 sample is superconducting below 30 K. This provides a remarkably simple and effective way to study the relationship between structure, superconductivity, and associated electronic properties. Variation in Cu 1 -O 4 , Cu 2 -O 4 and Cu 2 -O 2 bond lengths with oxygen content, is seen through the structural refinement of XRD pattern. The effective coordination of Cu 2 atom with oxygen changes with the change in these bond lengths and hence the holes in the CuO 2 planes. The charge-transfer mechanism from CuO x chains to CuO 2 planes and thus effective hole doping is discussed in the context of the results observed.

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Section: Resultssupporting

confidence: 78%

“…The increase of c-parameter in oxygen deficient samples is in agreement with Refs. [17,20,24]. The reason for this increase in cparameter will be discussed in forthcoming paragraphs.…”

Section: Resultsmentioning

confidence: 93%

Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Singh

Husain

Awana

2012

J Supercond Nov Magn

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“…However, when AϭBa and RϭY, single phase samples are obtained only up to xϽ0.20. [11][12][13] Therefore, the Cu͑Ba 0.8 Sr 0.2 ͒ 2 (Yb 1Ϫx Ca x )Cu 2 O 6ϩz system, in which the solubility limit of Ca has been extended up to xϷ0.40, 14 was selected for the present systematic investigation of the Casubstitution and O-doping effects. ͑Note that for the amount of excess oxygen, z is used instead of ''1Ϫ␦.…”

Section: 3mentioning

confidence: 99%

Ca-substitution and O-doping effects in superconductingCu(Ba0.8Sr0.2
Karppinen
¹
,
Yamauchi
²
,
Fujinami
³

et al. 1999
Phys. Rev. B
17
2
13
0
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Distinct calcium and oxygen doping effects were studied in the Cu͑Ba 0.8 Sr 0.2 ͒ 2 (Yb 1Ϫx Ca x )Cu 2 O 6ϩz (Cu-1212: P) system by means of neutron diffraction and superconducting quantum interference device experiments in the wide substitution ranges of 0рxр0.35 and 0ϽzϽ1. The effectiveness of the two different ways to introduce holes into the CuO 2 planes was compared both in respect to the capability to increase T c and in terms of the hole production as estimated from neutron-diffraction data via bond-valence-sum calculation. Oxygen doping was found to increase the hole concentration less efficiently, and further, at a certain hole concentration value higher T c values were obtained with calcium substitution than with oxygen doping. The two different hole-doping methods exhibited also different T c vs Cu-O bond length relations. As a conclusion, the possible roles of the hole distribution in the in-plane Cu-O bond and the flatness of the CuO 2 planes in determining the superconducting properties were recognized. ͓S0163-1829͑99͒06929-5͔

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“…The situation of co doping is more complicated than doping with one element. Doping alone, Mg substitutes Cu on Cu 2 O planes' site and Jc decreases as reported by various authors [15][16][17][18][19][20][21][22][23][24][25]. Our results show a different behaviour: possibility of substitution on chain's site and enhancement of Jc.…”

Section: Magnetization Measurementsmentioning

confidence: 31%

“…When the samples are co doped with Ca and Mg, both ZFC and FC curves show a decrease of the width of the transition when the content of Mg is increased. The change of charge carrier density due to doping with Mg [15][16], the induction of mobile holes by substitution with Ca [17][18] coupled or no with various structural changes [19], overall oxygen content and the disorder in Cu-O 2 planes [8][9][10][11][12][13][14][15][16][17][18][19][20] are various mechanisms responsible for variation of Tc. The magnetization curves show also that the amount of the difference ∆M between the Meissner effect (FC) response and the effect of the shielding current lines (ZFC) increases with Ca content and decreases with Mg content.…”

Section: Magnetization Measurementsmentioning

confidence: 99%

The influence of doping with Ca and Mg in YBa₂Cu₃O_7-δceramic

Attaf

Mosbah

Vecchione

et al. 2012

EPJ Web of Conferences

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Abstract.We have investigated the effect of partial substitution of Ca for Y and/or Mg for Cu on structural, compositional and magnetic properties in YBa 2 Cu 3 O 7-δ polycrystalline compounds. All prepared samples were found to be single phase with small fraction of Ba-secondary phases. Substitution by more than 2% of magnesium causes an increase of spurious phases. Energy Dispersive Spectroscopy (EDS) revealed that the distribution of Ca in the sample is quite homogenous. DC susceptibility measurements show that superconducting transition temperature Tc is reduced much more by Ca than Mg. Hysteresis loops reveal that magnetic irreversibility is decreased by Ca and Mg content. The deduced critical current density Jc does not follow the same variation. Ca alone reduces Jc for x=0.1 and x=0.2. Together with Ca, Mg compensates the reduction of Jc and increasing its content near the solubility limit gives higher Jc than in the undoped sample.

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Structural aspects and superconductivity in oxygen-deficient Y1−xCaxBa2Cu3O7−y (y ≈ 0.3) system A neutron-diffraction study

Cited by 55 publications

References 15 publications

Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Ca-substitution and O-doping effects in superconductingCu(Ba0.8Sr0.2
Karppinen
¹
,
Yamauchi
²
,
Fujinami
³

et al. 1999
Phys. Rev. B
17
2
13
0
View full text Add to dashboard Cite

The influence of doping with Ca and Mg in YBa₂Cu₃O_7-δceramic

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Structural aspects and superconductivity in oxygen-deficient Y1−xCaxBa2Cu3O7−y (y ≈ 0.3) system A neutron-diffraction study

Cited by 55 publications

References 15 publications

Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Structure and Charge-Transfer Mechanism in Y1−x Ca x Ba2Cu3O7−δ Through Direct Doping

Ca-substitution and O-doping effects in superconductingCu(Ba0.8Sr0.2Karppinen1, Yamauchi2, Fujinami3 et al. 1999Phys. Rev. B172130View full textAdd to dashboardCite

The influence of doping with Ca and Mg in YBa2Cu3O7-δceramic

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Ca-substitution and O-doping effects in superconductingCu(Ba0.8Sr0.2
Karppinen
¹
,
Yamauchi
²
,
Fujinami
³

et al. 1999
Phys. Rev. B
17
2
13
0
View full text Add to dashboard Cite

The influence of doping with Ca and Mg in YBa₂Cu₃O_7-δceramic