Year: 2014
Type: article
Abstract: A first-principles study of the electronic properties of a CaSO 4 anhydrite structural phase has been performed. A theoretical estimation for the fundamental band gap (p → s transitions) is E g = 9.6 eV and a proper threshold for p → d transitions is E pd = 10.8 eV. These values agree with the data obtained for a set of CaSO 4 doped with Gd 3+ , Dy 3+ , Tm 3+ and Tb 3+ ions using the methods of low-temperature highly sensitive luminescence and thermoactivation spectroscopy. The results are consistent with theoretical predictions of a possible low-temperature self-trapping of oxygen p-holes. The hopping diffusion of hole polarons starts above ∼40 K and is accompanied by a ∼50–60 K peak of thermally stimulated luminescence of RE 3+ ions caused due to the recombination of hole polarons with the electrons localized at RE 3+ . There is no direct evidence of the self-trapping of heavy d-electrons, however, one can argue that their motion rather differs from that of conduction s-electrons.
Source: Physica Scripta
Institutions: University of Tartu, Tallinn University of Technology
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2064483179