  Self-doping in YBa2Cu3Oy starts to switch from a charge balancing of chain
metal reduction and plane oxidation to one of chain ligand oxidation (O-) and
plane reduction on quenching from >600K. Amongst the responses are plane
expansions and types of unusually strong superconductivity such as elevated
temperature superconductivity (ETS), observed through laser pulsing (Tc=552K*)
and upon shot quenching (Tc=200K*). We ascribe ETS to limited 3-D
superconductivity due to a correlated system of bond ordering within
chain-plane sandwiches and propose how to stabilize it. Accordingly, plane
expanding n-doping arises from self-doping charge equilibration with local
chain Cu of two-fold O coordination (2). The dumbbell type bonds of both apical
O- are a result of high-energy environment and comparable in their metric with
electron pairs on the plane. Following empirical Tc=%(2)x11 we suggest
increasing %(2) to cause the observed retrograde rise in Tc (photo-induced
reflectivity edge) to a theoretical limit of Tc=1100K* at 100%(2). We propose
compositions and heat treatments based on charge-lattice commensurability.
Paired charge concentrations on planes, determined by bond ordering based on
magic number counts, suggest several promising candidates such as
c=0.22=2/3a0x3b0, c=0.17=2/3x4 or c=0.080=2/5x5. The latter could be achieved
with 32%(2) and display Tc=352K* not only in laser pulsed but in shot quenched
materials.
