Detection of a Li rich skin on LiNbO sub 3 single crystals.

Optical and DTA measurements of a single crystal of LiNbO sub 3 pulled from the congruent melt indicate a radial compositional gradient leading to a Li rich surface. From T sub c measurements it is concluded that the surface is >=0.15 mole % Li sub 2 O richer than the bulk composition. The skin thickness is = 1 mm and is generally removed prior to device preparation, however, some possible sources of concern are discussed for subsequent high temperature processing.