Year: 1981
Type: article
Abstract: Audio-frequency capacitance and conductance measurements have been carried out for calcium fluoride doped with 1.0 mol.% of thirteen rare earths, and 10 and 20 mol.% of erbium and lanthanum; strontium fluoride doped with 0.1 and 1.0 mol.% of twelve rare earths, yttrium and lanthanum; and barium fluoride doped with 0.1 mol.% of twelve rare earths, yttrium and lanthanum. For the moderately doped calcium fluoride samples, it is found that the low-temperature (R III ) relaxation dominates the spectrum for small rare earths. For large rare earths, the dimer-associated R IV ('gettered' 2:2:2) relaxation dominates the spectrum. The primary result for strontium fluoride is the observation of a new relaxation in the heavily doped samples with an activation energy which depends strongly upon the size of the rare earth and thus is attributed to R IV dimers. Other results may be summarised as follows. The R IV dimer becomes less stable as the host size increases but also as the rare earth size decreases. For smaller rare earth dopants, R III is more stable in the smaller hosts and appears at lower concentrations in smaller hosts. Correspondingly, the complexity of the dielectric spectrum increases for smaller hosts and smaller rare earth dopants.
Institution: Case Western Reserve University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2016597408