A systematic optical study of the Ba_1-xK_xBiO₃ system

W. Markowitsch^b,a, H. Jodlbauer^b,a, V. Schlosser^b,a, W. Lang^b,a, K. Remschnig^c, P. Rogl^c

1. Ludwig Boltzmann Institut für Festkörperphysik, Kopernikusgasse 15, A-1060, Wien, Austria

2. Institut für Festkörperphysik der Universität Wien, Austria

3. Institut für Physikalische Chemie, Universität Wien, Austria

ABSTRACT: Reflection spectra of Ba_1-xK_xBiO₃ over a wide spectral range are reported. For x lower than the critical value of approx. 0.35 contributions of free carriers, interband transitions and midgap absorption processes are observed. The plasma frequency is small (< 0.1 eV) for all x below the insulator to metal transition. Increasing x from 0 to approx. 0.1 results in a transfer of oscillator strength from the interband maximum to a midgap maximum. For x = 0.3 a flat plasma edge is observed, which is deformed by remainders of both the interband and midgap maxima.

DOI: 10.1016/0921-4534(91)91720-O