Abstract

While α-quartz is trigonal, optically (+), the biaxial spectra of interstitial Fe⁴⁺ appears to have orthorhombic symmetry with oscillator strength, f, equal 0.011 for E in π and σ and for normal light in a wafer cut in $\left(1\overline{1}00\right)$. In a wafer cut in (0001), f is 0.011 with E║ a and 0.0065 with E ⊥ a. In normal light in the a-plane f is 0.0084 (while the vectorial average is 0.0087). Evidence is presented that Fe⁴⁺ can only be interstitial and only appear in major rhombohedral, r, growth in α-quartz, as the mechanism of its production requires the presence of potential trapped-hole centers which are quenched by the electron donor role of interstitial Fe³⁺.

© 1984 Optical Society of America