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The Small Polaron Problem with an Application to Optical and DC Data of Reduced Barium Titanate
Author(s) -
Reik H. G.,
Heese D.
Publication year - 1967
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.19670240127
Subject(s) - polaron , phonon , barium titanate , condensed matter physics , polarization (electrochemistry) , titanate , materials science , conductivity , physics , chemistry , quantum mechanics , optoelectronics , dielectric , composite material , ceramic , electron
Reflectivity data from 1 to 12 μm for four samples of reduced BaTiO 3 with dc conductivities between 20 and 240 (Ωcm) −1 are analysed in terms of small a polaron theory. Quantitative agreement between theory and experiment is found except for the sample with the highest conductivity. By fitting the optical data it is found that the parameters of the theory the average frequency of the optical phonons, Ω0, and the number η of phonons in the polarization cloud, have the values Ω0 = 1.265 × 10 14 s −1 and η = 7. These parameters also determine the temperature dependence of the dc mobility. A weak temperature dependence of the mobility is found theoretically and is in agreement with the experimental data.