Original paper

Temperature-dependent absorption of biotite: small-polaron hopping and other fundamental electronic excitations

Rüscher, Claus H.

Abstract

Temperature-dependent absorption investigations between 10 and 823 K reveal photon-assisted hopping (PAH) of small polarons in biotites as the dominating excitation in the near-infrared spectral range. These data show a transfer of oscillator strength of the PAH of small polarons to Fe2+-Fe3+ intervalence-charge transfer and Fe2+ d-d transitions with decreasing temperature. The loss in oscillator strength of PAH is related to a pinning of the polarons due to the decreasing number in lattice vibrations in thermal equilibrium.

Keywords

biotitesmall-polaron absorptionintervalence-charge transfer