Effect of Fe substitution on the thermal expansion of the highT c superconductor Y1Ba2Cu3O y

Influence of Zn doping on the thermal expansion of the highTcsuperconductor Y1Ba2Cu3Oy

“…Meingast et al [7] have also reported some anomalies, like a jump in α at T = 250 K, hysteresis in the temperature region 50 T < 250 K and non-reversible length changes at low temperature (T < 45 K), for specimens with higher concentration. Anomalies of this type have been observed by Rao et al [10][11][12]. In fact they have also observed that two specimens cut out of the same sample behave differently.…”

“…Detailed thermal expansion studies have been carried out by many investigators on the dopants which occupy copper plane sites. These reports indicate that the jump in thermal expansion increases with an increase in dopant concentration [7,10,11].…”

“…However no such transformation is observed for Zn and Ni that occupy chain sites [4][5][6]. Because of structural changes, doping by Fe, Co, Ni, etc affects not only the properties associated with the superconducting state of YBaCuO but also properties like the lattice components of specific heat [7,8], coefficient of thermal expansion [7,[9][10][11][12][13] and the pressure dependence, dT c /d P of T c [14][15][16][17]. Detailed thermal expansion studies have been carried out by many investigators on the dopants which occupy copper plane sites.…”

The influence of Mn doping on the thermal expansion of the highTCsuperconductor YBa2(Cu1−xMnx)3Oy

“…Doping with Fe, Co, Ni, Zn, etc in YBa 2 Cu 3 O y not only alters the superconducting transition temperature T C to a large extent, but also influences other physical properties such as the lattice components of the specific heat [8,9] and the coefficient of thermal expansion [6][7][8][10][11][12][13]. Thermal expansion is a useful tool for providing valuable information about the changes in the electronic and phononic properties across the superconducting transition [9,14].…”

“…The close relation between the specific heat and thermal expansion of solids (Grüneisen formalism) can be effectively utilized for a detailed thermodynamic treatment (Ehrenfest relations) of phase transitions, and such studies have been widely carried out by many investigators on the dopants which occupy copper plane and chain sites in the high T C superconductor YBa 2 Cu 3 O y [9,14,15]. These reports indicate that for dopants like Fe and Co, the jump in thermal expansion increases with the increase in dopant concentration [8,11,12]. On the other hand, such a jump decreases with the contents of dopants such as Ni and Zn [6,7].…”