Reaction of YBa2Cu 3O6 with Br2: oxidation and formation of nanoscale YBa2Cu3O7

O-K and Co-L XANES Study on Oxygen Intercalation in Perovskite SrCoO3-δ

“…Examples of other structure types to allow topotactic intercalation of oxygen are YBaCo 4 O 7þδ , 11 YCuO 2þδ 12 and YBa 2 Cu 3 O 7-δ . 13 Previous results from topotactic electrochemical oxidation experiments [14][15][16] suggest that oxygen diffusion into the material has two stages: (i) fast diffusion occurring via a network of extended defects and (ii) slow diffusion inside microdomains enclosed by the defect network leading to observable structural changes. There have been various suggestions for the diffusing oxygen species, that is, O 2-, O 3 5-, O -, O 2 2-, and O 2 -.…”

“…Two of the most well-known oxide systems being prone to topotactic oxidation are (i) the Ruddlesden−Popper oxides such as La 2 CoO 4+δ , La 2 NiO 4+δ , and La 2 CuO 4+δ ,; and (ii) the perovskite oxides such as SrFeO 3-δ , and SrCoO 3-δ , − the former accommodating the intercalated oxygen at interstitial sites and the latter at oxygen vacancy sites. Examples of other structure types to allow topotactic intercalation of oxygen are YBaCo 4 O 7+δ , YCuO 2+δ and YBa 2 Cu 3 O 7-δ …”

Homologous Series of SrCoO(3n−1)/n Perovskites Obtained Through Br2 Oxygenation of SrCoO2.5

“…Such topotactic redox reactions typically proceed via intercalation/deintercalation of cation or anion species within a crystal lattice with either vacancy or interstitial defects. Examples include the perovskite oxides SrCoO 3-δ , [1][2][3] SrFeO 3-δ , 4,5 and YBa 2 Cu 3 O 7-δ 6 with oxygen vacancies ordered in various ways, the K 2 NiF 4 -type oxide La 2 CuO 4+δ 7 with oxygen interstitials, and the layered alkali compounds Li x CoO 2 , 8,9 Na x CoO 2 , 8,10 and Li x NiO 2 11 with cation vacancies. Here we focus on the SrCoO 3-δ system in which several (metastable) oxygen-deficient single phases of orthorhombic, 1,12 tetragonal, 1 and cubic 2,3,13 symmetries have been attained up to now.…”

“…The main question concerned whether it would be possible to identify some of the members of the SrCoO (3 n −1)/ n series which have remained unattainable in studies employing other oxygenation routes, that is, electrochemical , and high-pressure high-temperature , oxygenation routes. So far alkaline hypobromite BrO − solutions have been used as an oxidant for various Cu, Fe, and Co oxides, that is, La 2 CuO 4+δ , YCuO 2+δ , SrFeO 3−δ , and SrCoO 3−δ , , whereas pure bromine vapor has been used for YBa 2 Cu 3 O 7−δ . Here we aim at better controllability utilizing a Br 2 solution diluted with acetonitrile CH 3 CN (and H 2 O).…”