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Cao, Yiming; Hudson, T. L.; Wang, Y. S.; Xu, Siyun; Xue, Y. Y.; Chu, C. W.

doi:10.1103/physrevb.58.11201

Cited by 27 publications

(14 citation statements)

References 17 publications

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“…Secondly, we focus on the effects of strain on Schottky defects and related phenomena for a series of homovalent substitutions at Y and Ba sites of YBa 2 Cu 3 O 7−δ . Although the 123 structure is not stable in the Ca-and Sr-analogs under ambient pressure [23,24,25], partial substitution of Sr on the Ba site has been reported [4,23,26,27,28]. Finally, strain effects on chain-oxygen order-disorder transition of REBa 2 Cu 3 O 7−δ will be investigated.…”

Section: Introductionmentioning

confidence: 99%

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

Welch

Wong‐Ng³

2004

Phys. Rev. B

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The energetics of Schottky defects in 123 cuprate superconductor series, REBa2Cu3O7 (where RE = lanthandies) and YAE2Cu3O7 (AE = alkali-earths), were found to have unusual relations if one considers only the volumetric strain. Our calculations reveal the effect of non-uniform changes of interatomic distances within the RE-123 structures, introduced by doping homovalent elements, on the Schottky defect formation energy. The energy of formation of Frenkel Pair defects, which is an elementary disordering event, in 123 compounds can be substantially altered under both stress and chemical doping. Scaling the oxygen-oxygen short-range repulsive parameter using the calculated formation energy of Frenkel pair defects, the transition temperature between orthorhombic and tetragonal phases is computed by quasi-chemical approximations (QCA). The theoretical results illustrate the same trend as the experimental measurements in that the larger the ionic radius of RE, the lower the orthorhombic/tetragonal phase transition temperature. This study provides strong evidence of the strain effects on order-disorder transition due to oxygens in the CuO chain sites.

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Section: Introductionmentioning

confidence: 99%

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

Welch

Wong‐Ng³

2004

Phys. Rev. B

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“…As mentioned by Cao et al [11], their overdoped samples have dT c /dp = 3.0 K/GPa, which is in contrast with the PICT model, since we expect a decrease of T c with the increase of hole content by applied pressure in the overdoped regime. It is resulted that in spite of the lower charge transfer to the CuO 2 plane in YSCO relative to YBCO, the dT c /dp for YSCO is larger than for YBCO.…”

mentioning

confidence: 67%

“…In recent HPE study, a dT c /dp = 0.64 K/GPa [10] has been derived for YBCO single crystals up to 6 GPa, but this value in some isostructural YBCO-related compounds is completely different from YBCO, such as 3 K/GPa [11], 5.5 K/GPa [12], and 7.4 K/GPa [13] for YSCO, Y124, and Pr123, respectively. In this paper we have compared the HPE on two HTSC isofamilies, YBCO and its chemically pressured YSCO by density functional theory in the range of -15 At first, the equilibrium ionic positions were considered for each pressure, and they were relaxed to new equilibrium positions.…”

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confidence: 98%

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High pressure effects in YBCO and YSCO

Khosroabadi

Mossalla

Akhavan

2004

phys. stat. sol. (c)

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“…The Sr doping, however, scarcely increases T c for Y124 [4], or remarkably decreases T c for YBa 2 Cu 3 O 7−δ [14][15][16][17][18], although the unit cell volume shrinks (the unit cell volume of Y124 with Sr of x=0.3 corresponds to that under an external hydrostatic pressure of about 2.4 GPa [19]). Hence, one can suspect randomness effect on the actual T c .…”

mentioning

confidence: 99%

Cu nuclear quadrupole resonance study of site disorder and chemical pressure effects onY(Ba1−xSrx
Itoh
¹
,
Adachi
²
,
Machi
³

et al. 2001
Phys. Rev. B
10
0
8
0
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We report a zero-field Cu nuclear quadrupole resonance (NQR) study on the effects of nonmagnetic Sr substitution for high-Tc superconductors, Y(Ba1−xSrx)2Cu4O8 (Tc=82-80 K for x=0-0.4), using a spin-echo technique. The site-disordering and chemical pressure effects associated with doping Sr were observed in the broadened, shifted Cu NQR spectra. Nevertheless, the site disorder did not significantly affect the homogeneity of Cu electron spin dynamics, in contrast to the in-plane impurity. The peak shift of Cu NQR spectrum due to Sr was different between the chain-and the plane-Cu sites, more remarkably than those under a hydrostatic physical pressure, suggesting anisotropic or nonuniform local structural strains. The small decrease of Tc due to Sr can be traced back to either a cancellation effect on Tc between the disorder and the pressure, or an anisotropic or nonuniform chemical pressure effect on Tc. The role of imperfections in quantum many-body systems has attracted strong attention [1,2]. In high-T c cuprate superconductors, an additional impurity potential is introduced through the in-plane or out-of-plane element substitution for the CuO 2 plane. There is a belief that site disorder does not cause serious damage to the electronic states of the CuO 2 plane. However, the reason why chemical pressure effect on T c due to the element substitution is not the same as the physical (external) pressure one has been frequently ascribed to the randomness effect. How the site disorder changes the electronic states has been a problem.Here, we focus on the divalent Sr 2+ -doped high-T c superconductors, Y(Ba 1−x Sr x ) 2 Cu 4 O 8 . Since the stoichiometric and naturally underdoped YBa 2 Cu 4 O 8 (Y124) with T c =82 K has the exceptionally tight oxygen content, the Sr-doped Y124 is a suitable system to study the site-disordering effect on the electronic states. To be exact, one can expect two effects of Sr substitution for Ba in Y124 without change of oxygen content; (1) the chemical pressure and (2) the crystalline potential disorder. The substitution of Sr 2+ ions causes no additional local (formal) charge in Ba 2+ O 2− layers. However, the size of Sr 2+ ion is smaller than that of Ba 2+ by about 10 % [3], so that the substituted Sr ions make local crystalline strains on the BaO layers. Thus, the Sr doping introduces crystalline potential disorder and chemical pressure to the lattice. Actually, the lattice constants shrink with doping Sr [4], being in parallel to the physical pressure effect [5].The effect of hydrostatic physical pressure on the spin dynamics is similar to the carrier doping effect [6][7][8]:The physical pressure effects on T c and on the pseudo spin-gap temperature T s agree with the carrier doping effects, i.e. with applying the physical pressure to Y124 (T c =82 K and T s ∼160 K at an ambient pressure P =0

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High-temperature superconductingYSr2Cu3O7.5

Cited by 27 publications

References 17 publications

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

High pressure effects in YBCO and YSCO

Cu nuclear quadrupole resonance study of site disorder and chemical pressure effects onY(Ba1−xSrx
Itoh
¹
,
Adachi
²
,
Machi
³

et al. 2001
Phys. Rev. B
10
0
8
0
View full text Add to dashboard Cite

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High-temperature superconductingYSr2Cu3O7.5

Cited by 27 publications

References 17 publications

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

High pressure effects in YBCO and YSCO

Cu nuclear quadrupole resonance study of site disorder and chemical pressure effects onY(Ba1−xSrxItoh1, Adachi2, Machi3 et al. 2001Phys. Rev. B10080View full textAdd to dashboardCite

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Cu nuclear quadrupole resonance study of site disorder and chemical pressure effects onY(Ba1−xSrx
Itoh
¹
,
Adachi
²
,
Machi
³

et al. 2001
Phys. Rev. B
10
0
8
0
View full text Add to dashboard Cite