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|Title:||A Study of The a-β Phase Transformation in A1PO4:Fe^3+ and Quartz by Electron Paramagnetic Resonance|
Datars, W. R.
|Keywords:||phase transformation;electron;paramagnetic resonance;hydrothermal crystals|
|Abstract:||<p> The a-β phase transformation was studied in hydrothermally grown crystals of A1PO4 by measuring the spin-Hamiltonian parameters of Fe^3+ as a function of temperature. </p> <p> The theory of the Blume-Orbach mechanism for the zero-field splitting of s-state ions was generalized and used to calculate the D-tensor of the spin-Hamiltonian. The experimentally observed temperature variation of the spin-Hamiltonian was interpreted in terms of a temperature-dependent point-multipole model of the charge distribution in the crystal lattice. </p> <p> A similar study of the a-S phase transformation in quartz was attempted but E.P.R. measurements could only be taken up to 450°C (123°C below the transformation temperature) because of the instability of the Fe^3+ center at higher temperatures. </p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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