Covalency and hyperfine structure constant A of iron group impurities in crystals

Covalency Effects in Hyperfine Interactions in Alkali Dithioferrates

“…Other estimates of effective charges can be obtained from the 4s electron densities i. e. E. F. = 3.0 -4 x Q,,. Using these values of effective charges and assuming that the fields are proportional [3,5,[19][20]231 to ionic character (E. F.13.0) of Fe3+, the estimated spread of the internal fields lie in the range 160-216 kG and is in good agreement with the measured values. Our experimental measurements lie in the total range obtained from these three independent estimates (Table 11).…”

“…This has been emphasized to be true at least in very covalent crystals and for tetrahedral coordination, where sizable reduction of the hyperfine fields are accompanied by small 3d covalency [5].…”

“…Zero point motion of the spins cannot account for such a large reduction [18]. It has also been shown that the apparent percentage of delocalization of the antibonding 3d electrons in the %,,, state to the neighboring atoms is generally very small and cannot be the primary cause for the reduction of the hyperfine fields [5].…”

“…[5]). The limited but rather satisfying results discussed in this paper suggest the possibility of characterizing an isostructural series of compounds by one well defined covalency parameter, which would serve to link the various hyperfine interactions, facilitating the interpretation of experimental measurements.…”

Effect of Diffusion on (ZrO2)0.8(Y2O3)0.2Ceramic

“…The magnitude of hyperfine interaction parameter |A| may provide a measure of covalency of metal ion. I ' , is believed that |A| decreases with covalency and a relation in |Α | and covalency has been established for Mn 2 + in simple crystal systems by Śimánek and Muller [17].…”