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A Phase Transition and the Photoemissive Quantum Yield at Low Temperatures in Cs 3 Sb Films
Author(s) -
De'Munari G. M.,
Giusiano F.,
Mambriani G.
Publication year - 1968
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19680290135
Subject(s) - phase (matter) , quantum yield , valence (chemistry) , phase transition , yield (engineering) , materials science , intensity (physics) , chemistry , crystallography , analytical chemistry (journal) , condensed matter physics , physics , optics , organic chemistry , fluorescence , chromatography , metallurgy
By means of a recently developed method the photoemissive quantum yield ( Y ) of Cs 3 Sb films is measured as a function of temperature at very low light intensities. A strong evidence for the existence of Cs 3 Sb in two phases one of which (phase II) is the known “state” with high Y is found. The other phase (I) has a much lower Y which depends strongly on the light intensity. Phase I exists only below (260 ± 2) °K: above this temperature it transforms to phase II. The existence of phase I up to now was not noticed because it is very sensitive to the absorbed light energy which easily can convert it to phase II. We suggest for phase I the regular body‐centred cubic structure and for phase II the pseudo‐body‐centred cubic structure found at room temperature by Jack and Wachtel. Moreover, we propose for Cs 3 Sb an energy band structure with a split valence band. The observed dependences of Y on temperature and light intensity are discussed in this framework. Even other Cs 3 Sb properties seem to fit rather well the proposed energy band and crystal structure.