A different type of oxygen order in RE Ba2Cu3O(6+x) HTc superconductors with different RE ionic radii

Phase separation in oxygen deficient ΗοBa2Cu3O7-δ single crystals: effect of high pressure and twin boundaries

“…In oxygen deficient HTSC compounds of the 1-2-3 system the rare earth ion is sensitive to the local symmetry of its environment and to the charge density distribution. Their change affects the crystalline field, forming the electronic structure of this ion [7]. A characteristic peculiarity of the oxygen deficit samples (with δ ≥ 0.3) is the broadening of the resistivity transfers under pressure [5,8,9].…”

The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model

“…On the other hand, Gawiec et al [31,32] suggested that in the chain of length a certain number of oxygen ions can exist in the O − state, so that in this model the number of holes created is reduced implying that chains of length = 1 2 transfer no holes, chains of length = 3 and = 4 can transfer 1 and 2 holes, respectively, while the number of holes transferred from longer chains has been roughly estimated to be ∼ 0 7 [31]. Furthermore, some authors suggested that holes can be transferred only out of the chains that comprise more than three oxygen atoms ( = 4) [8,34]. Recently a simple charge transfer model was proposed in order to obtain the 60 K plateau in the T ( ) dependence in terms of the well known two dimensional ASYNNNI model [26][27][28].…”

Effect of Oxygen Redistribution on Temperature Dependence of Pseudo-Gap in Underdoped HoBa2Cu3O7-δSingle Crystals

“…The T c (δ) dependence characteristic of YBa 2 Cu 3 O 7−δ with two plateaus at 60 K and 90 K degenerates into a usual monotonically dependence. Additionally, the ortho-II structure is not realized at all [12]. It can be assumed that oxygen hypostoichiometric HoBa 2 Cu 3 O 7−δ compounds have a more extended disordered oxygen hyperstructure than YBa 2 Cu 3 O 7−δ compounds.…”

“…In HoBa 2 Cu 3 O 7−δ the Ho ion (which has larger ionic radius than Y) plays an important role in the structural ordering of the system, which affects the interactions between oxygen ions in the CuO planes. Earlier study revealed that when Y is substituted by the rare-earth elements with larger ionic radius, significant qualitative changes in the T c (δ) dependence in ReBa 2 Cu 3 O 7−δ [12] appear. The T c (δ) dependence characteristic of YBa 2 Cu 3 O 7−δ with two plateaus at 60 K and 90 K degenerates into a usual monotonically dependence.…”