TRANSPORT PROPERTIES AND AC SUSCEPTIBILITIES OF (Bi_1.6Pb_0.4)(Sr_1.8Ba_0.2)Ca₂(Cu_1–xNi_x)₃O_y SUPERCONDUCTOR

Abstract

The effect of the partial substitution of Cu by Ni in the stabilized 108 K phase was investigated by electrical resistance and a.c. susceptibility measurements. Up to a Ni concentration x = 0.02 the bending of the R (T) curve above T c can be described in the terms of the Lawrence-Doniach theory. The intergrain and intragrain critical transition temperatures decrease to ∆T CG = 9 K and ∆T j = 10.9 K respectively by the Ni substitution in the Cu-O pyramids.

EFFECT OF Ni SUBSTITUTION FOR Cu IN THE VORTEX STATE OF (Bi,Pb):2223 SUPERCONDUCTOR

“…The Partial substitution of Ni for Cu in the 110 K phase Bi:2223 revealed that nearly a single phase can be obtained up to x = 0.015 Ni and the critical transition temperature T c monotonously decreased in the region x ≤ 0.03. [4][5][6] The T c depression in the x = 0.02 Ni and Fe doped (Bi,Pb):2223 sample 6,7 agrees with that found in Ni and Fe doped Bi:2223 single crystal with x ≤ 0.02 when Cu atoms are replaced by 3d in the Cu-O pyramids. 8 The activation energies in x = 0.00 and x = 0.02 Fe doped 2223 sample are characterised by a [1−(T /T c )] ln B dependence, indicating a TAFF regime in the vortex liquid state.…”

“…The increase in residual resistivity, ρ(0) from 87 µΩ · cm to 377 µΩ · cm with increasing x from zero to 0.02 Ni is accompanied by the depression of the critical transition temperature T c from 109 K to 99.5 K. 6 The decrease of critical transition The broadening of the resistive transition for x = 0.02 Ni sample becomes more evident when the dρ/dT versus T curves in magnetic field are plotted as in Fig. 2.…”

“…3 We analysed the U (B) curves in the framework of the model by Innui et al 13 by using Eq. (6). The fit parameters are U 0 = 1230 K, σ = −848 K, for x = 0.00 sample and U 0 = 749 K, σ = −440 K for x = 0.02 Ni respectively.…”

“…6 The characterisation of the phase purity was carried out by X-ray diffraction with a DRON II equipment with CrK α radiation. The XRD analysis confirmed the presence of a single "2223" phase in the x = 0.0 sample.…”

Effect of Mo substitution on the structural and transport properties of Bi2Sr2Ca2Cu3−xMoxO10+y system

“…Tel. : +90 422 3410010x3720; fax: +90 422 3410037. grain formation and intergrain properties of the Bi-based system were highly influenced by the partial substitution of Cu by 3d-elements [2][3][4][5][6]. The substitution of Ni and Fe for Cu site showed a monotonically decrease on T c with the increase on the substitution levels.…”