The electrooptic and ferroelectric properties of glass-ceramic systems containing nao.3ko.snbos and batioaas the crystalline phases are presented. domain activity is observed by dielectric and optical hysteresis measurements, although it becomes significant only at the larger crystallite size. thus, the samples transmit light to only a small extent. bistable optical switching has been achieved with lo5 v/cm /cm, loo-vs duration pulses. the ratio of transmission measured between crossed polarizers is 2: 1. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.