ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The Newman superposition model, using certain empirical "intrinsic'' parameters, is commonly used in attempts to obtain information about the local environment of impurity ions in crystals from experimental data such as electron paramagnetic resonance (EPR) spin-Hamiltonian data. Using this model, we have developed equations relating the positions of four near-neighbor ions relative to a central paramagnetic ion to EPR crystal-field parameters eBl,m. We have explored the restrictions and hazards involved in using these equations in a fitting procedure. A set of experimental eBl,m parameters, measured for Fe3+ in quartz, has been used here in an attempt to determine the coordinates of four oxygen ions thought to be surrounding the iron located in a silicon site. We find that the result of fitting to the second-order parameters eB2,m alone is consistent with the substitutional site model for the iron in quartz, but is unreliable in that there is actually an infinite number of fits to these parameters. Using the second-order and fourth-order parameters together gives a unique fit but one which seems physically unreasonable. Fitting to the second-order and fourth-order parameters using the intrinsic parameter B4(R0) as a fitting parameter along with the coordinate parameters gives a unique fit which strongly supports the substitutional model.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.452982
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