  A Raman profiling method is used to monitor growth of GexSe100-x melts and
reveals a two step process of homogenization. Resulting homogeneous glasses
show the non-reversing enthalpy at Tg, {\Delta}Hnr(x), to show a square-well
like variation with x, with a rigidity transition near xc(1) = 19.5(5)% and
stress transition near xc(2) = 26.0(5)%) representing the boundaries of the
rigid but stress-free Intermediate Phase (IP). The square-well like variation
of {\Delta}Hnr(x) develops sloping walls, a triangular shape and eventually
disappears in glasses having an increasing heterogeneity. The {\Delta}Hnr term
ages over weeks outside the IP but not inside the IP. An optical analogue of
the reversibility window is observed with Raman spectra of as-quenched melts
and Tg cycled glasses being the same for glass compositions in the IP but
different for compositions outside the IP. Variations of Molar volumes, display
three regimes of behavior with a global minimum in the IP and a pronounced
increase outside that phase. The intrinsic physical behavior of dry and
homogeneous chalcogenides glasses can vary sharply with composition near
elastic and chemical phase transitions, showing that the physics of network
glasses requires homogeneous samples, and may be far more interesting than
hitherto recognized.
