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(Color) Schematic of the FTIR setup; on the right hand side the chopped blackbody source radiation is focused on the sample inside the vacuum system by a telescope; on the left hand side, through a telescope, a Michaelson interferometer detects the radiance and/or reflectance of the sample. The three electron beam sources are indicated.
(Color) Sequence of reflectance spectra recorded during deposition and postannealing of YBCO on metal tape for (a) YBCO deposited at and (s489). Only one amorphous phase is detected (A) which resembles the phase below but probably differs slightly in density, as detected by nanoindentation experiments (Ref. 13 . (b) YBCO deposited at and pressure during postannealing limited to a few millitorrs, while cooled to low temperature (s442). Only phases and are detected; (c) Same as (b) but after deposition the oxygen pressure is further raised, initially to and upon cooling more oxygen is bled into the chamber (s434). The five detected phases are marked , , C, and ; : amorphous , : dense amorphous (glass, ), C: , : , : metallic leftover flux.
(Color) Phase stability diagram of YBCO and ; YBCO is found to be stable in the blue region and in equilibrium with liquid on the left side; A, , , C, , and schematically indicate the temperature and pressure of the phase transitions observed in Fig. 2 . The arrows schematically indicate the three cooling trajectories corresponding to Figs. 2(a)–2(c) ), respectively. The insets show pictures of the samples after taking them out of the chamber.
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