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arXiv · 1512.02281

Slow electronic rearrangement kinetic involving O- after shot quenching from >600K of YBa2Cu3Oy

H Oesterreicher
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Abstract

Analysis of kinetic literature suggests several electronic rearrangements above 600K involving O- (subperoxides) in YBa2Cu3Oy. Slow cooling to 260K produces a Tc=50K level with conventional plane and cell volume contracted varieties (P-V-), based on plane oxidizing (4) where (n) denotes local O coordination. When these materials are quenched from <600K, the subsequent changes at 298K of structural parameters or Tc have activation energies E=92kJ and A=1.0x10-12s. The changes saturate at temperatures where they are faster than the time constant t of quenching. This temperature is extended to 473K with SQ, indicating t=0.1s. SQ of y near 6.44 from >600K leads to increased axial ratios, plane and V expansion (P+V+), in a process which is complete near 670 and extending to 950K. P+V+ effects can far exceed P0V0 of the respective semiconductor. The relative stability at elevated temperatures indicates another intrinsically slower transformation mechanism of primarily electronic nature with E=280kJ, involving O-. V+ and its Tc=100K level, is ascribed to (3) with doped charge on apical O-, acting as a plane expander and n-doper. Similar slowing of kinetic through O- also hold for the more complex range of Tq>950K. It can produce a c-axis contracted non-superconductor (P+C-) and indications for elevated temperature superconductivity (ETS) with Tc>150K*. Kinetic data are embedded into general thermodynamic arguments concerning peroxide stability belts.

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H Oesterreicher. 2015-12-07. Slow electronic rearrangement kinetic involving O- after shot quenching from >600K of YBa2Cu3Oy. https://arxiv.org/abs/1512.02281

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