Growth of single crystals of transition metal oxides by the arc-transfer method

Abstract

A new method for preparing single crystals of refractory oxides by the direct transport of material across the gap of a d.c. arc has recently been described by Drabble and Palmer. We report here observations on the growth characteristics of NiO, CoO, Fe 3 O 4 and Mn 3 O 4 crystals and other oxides by this method including the influence of the ambient atmosphere and Li doping. CoO and Fe 3 O 4 have been examined in detail in an attempt to understand the growth process. The transfer mechanism remains obscure, but over a limited range of arc-currents the variation of ingot diameter can be explained by assuming that the heat losses are radiation limited. The linear growth rates are generally small (≁ 4 mm/hour) and independent of current over most of the lower range. Some practical difficulties and limitations of the method are also discussed.