Attack of YBa2Cu3O6.8 by acidic aqueous solutions
The dissolution of YBa2Cu3O6.8 in acidic aqueous solutions was studied at 298 K as a function of pH, nature and concentration of present anions and time, t. In the range 2.0 ≤ pH ≤ 4.0, dissolution is congruent and proceeds to completion; dissolution profiles are deceleratory and comply with a contr...
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1996
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paper:paper_00222461_v31_n1_p54_Candal2023-06-08T14:47:42Z Attack of YBa2Cu3O6.8 by acidic aqueous solutions Candal, Roberto Jorge Barium Chemical reactions Copper Dissolution Ions Leaching Oxidation pH Precipitation (chemical) Protons Solutions Surface phenomena Acidic aqueous solutions Oxidation state Passive layer Protonation Surface reactions Volume rate law Yttrium barium copper oxide Oxide superconductors The dissolution of YBa2Cu3O6.8 in acidic aqueous solutions was studied at 298 K as a function of pH, nature and concentration of present anions and time, t. In the range 2.0 ≤ pH ≤ 4.0, dissolution is congruent and proceeds to completion; dissolution profiles are deceleratory and comply with a contracting volume rate law up to t0.5. The rate of dissolution, which is limited by slow surface reactions, decreases with increasing pH; the kinetic order on proton concentration is a fractional and variable number. At higher pH values, dissolution is arrested at intermediate conversion values. In these cases, congruent dissolution is followed by the precipitation of less soluble solid phases which form a passive layer. The nature of this passive layer depends on pH and on the nature and concentration of present anions, which also define the extent of conversion attained at passivation. The dissolution behaviour of YBa2Cu3O6.8 is described in terms of two consecutive surface reactions: fast equilibrated protonation of surface metal ions is followed by the slow release of cations. Barium surface ions are identified as the more reactive sites. The effect of the fast initial leaching of barium ions on the reactivity of yttrium and copper sites is discussed. The influence of the formal Cu(III) oxidation state is also stressed. © 1996 Chapman & Hall. Fil:Candal, R.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1996 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222461_v31_n1_p54_Candal http://hdl.handle.net/20.500.12110/paper_00222461_v31_n1_p54_Candal |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Barium Chemical reactions Copper Dissolution Ions Leaching Oxidation pH Precipitation (chemical) Protons Solutions Surface phenomena Acidic aqueous solutions Oxidation state Passive layer Protonation Surface reactions Volume rate law Yttrium barium copper oxide Oxide superconductors |
| spellingShingle |
Barium Chemical reactions Copper Dissolution Ions Leaching Oxidation pH Precipitation (chemical) Protons Solutions Surface phenomena Acidic aqueous solutions Oxidation state Passive layer Protonation Surface reactions Volume rate law Yttrium barium copper oxide Oxide superconductors Candal, Roberto Jorge Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| topic_facet |
Barium Chemical reactions Copper Dissolution Ions Leaching Oxidation pH Precipitation (chemical) Protons Solutions Surface phenomena Acidic aqueous solutions Oxidation state Passive layer Protonation Surface reactions Volume rate law Yttrium barium copper oxide Oxide superconductors |
| description |
The dissolution of YBa2Cu3O6.8 in acidic aqueous solutions was studied at 298 K as a function of pH, nature and concentration of present anions and time, t. In the range 2.0 ≤ pH ≤ 4.0, dissolution is congruent and proceeds to completion; dissolution profiles are deceleratory and comply with a contracting volume rate law up to t0.5. The rate of dissolution, which is limited by slow surface reactions, decreases with increasing pH; the kinetic order on proton concentration is a fractional and variable number. At higher pH values, dissolution is arrested at intermediate conversion values. In these cases, congruent dissolution is followed by the precipitation of less soluble solid phases which form a passive layer. The nature of this passive layer depends on pH and on the nature and concentration of present anions, which also define the extent of conversion attained at passivation. The dissolution behaviour of YBa2Cu3O6.8 is described in terms of two consecutive surface reactions: fast equilibrated protonation of surface metal ions is followed by the slow release of cations. Barium surface ions are identified as the more reactive sites. The effect of the fast initial leaching of barium ions on the reactivity of yttrium and copper sites is discussed. The influence of the formal Cu(III) oxidation state is also stressed. © 1996 Chapman & Hall. |
| author |
Candal, Roberto Jorge |
| author_facet |
Candal, Roberto Jorge |
| author_sort |
Candal, Roberto Jorge |
| title |
Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| title_short |
Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| title_full |
Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| title_fullStr |
Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| title_full_unstemmed |
Attack of YBa2Cu3O6.8 by acidic aqueous solutions |
| title_sort |
attack of yba2cu3o6.8 by acidic aqueous solutions |
| publishDate |
1996 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222461_v31_n1_p54_Candal http://hdl.handle.net/20.500.12110/paper_00222461_v31_n1_p54_Candal |
| work_keys_str_mv |
AT candalrobertojorge attackofyba2cu3o68byacidicaqueoussolutions |
| _version_ |
1768541972273823744 |