Solid solution in the system BaCuO2CuOO2

Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations

“…The bad reproducibility of the 1:1 (Ba:Cu) composition indicates that this mate rial is very probably polyphasic. Instead, the 88:90 composition is proved monophasic by the regular trend of coupled gravimetric and diffractometric determinations, in agreement with other literature data [15]. The latter material is oxygen over-stoichiometric over the whole investigated T (300 -=-820 °C) G. Chi o d e lli et al ■ Defect Chemistry of BaCu0 2 II .…”

“…The regular trend of both measurements, and in particular the absence of a plateau in the XRPD data and/or a jump in the gravimetric data, is a clear indication that phases, at P ( 0 2)>0.2 atm. A better agreement can be seen with the results of a recent paper by Maiorova et al [15], who used TG dynamic measurements at a scan rate of 1 °C/min under a static oxygen atmo sphere on a "BaCu02" sample with Ba:Cu = 1.14.…”

“…Therefore we can provi sionally argue that "BaCu02" shows a measurable molecularity range, and that the 0.98 (Ba:Cu) ratio is inside its stability field (or very close to its boundary). Arguments in favor of the stability of the phase when Ba:Cu is near 0.98 are also given by recent EMF measurements [15].…”

“…After the first work by Arjomand and Machin [3], "BaCuO2" has been investigated as to space group symmetry [4], crystal structure determination from single crystal and powder Rietveld methods [5][6][7][8][9][10], oxygen non-stoichiometry and cation molecularity [9][10][11][12][13][14][15], thermodynamic data [15,16], Raman spec troscopy [17], electrical conductivity [4,11], thermopower [4,11], and magnetic and ferroelectric behavior [4,11,18]. Crystallography and crystal chemistry of Reprint requests to Prof. G. Spinolo. the various compounds in the whole Ba, Cu/O system have been recently reviewed by Wong-Ng and Cook [19].…”

Chemical principles of preparation of metal-oxide superconductors

“…Discrepancies in determination of the limits of oxygen nonstoichiometry in BaCuO 2 + z can be due to the formation of oxycarbonates [e.g., Ba 44 Cu 48 (CO 3 ) 6 O 87.9 , see Aranda and Attfeld 272 ] or to an ambiguous assignment of the specimens with other cation compositions to this phase. 273,274 A reliable thermodynamic assessment of the Ba7Cu7O system was reported. 273 The oxygen nonstoichiometry in the Ba 2 CuO 3 -, BaCuO 2 -and Ba 2 Cu 3 O 5 -phases was also discussed.…”