  From the days when superconductivity was discovered its science was entangled
by the unresolved problem of the relationship between superconductive state,
its crystal structure and its phase transitions. The problem was exacerbated by
the adjacent scientific area - solid state phase transitions - that offered to
divide phase transitions into first and second order. Adding to that the
conclusion (turned out erroneous)on the structural identity of the
superconductor and normal phases, the whole issue was uncertain and confusing.
This article straights it out.
