INDICATIONS OF AN INTERMEDIATE PHASE IN SINGLE-CRYSTALS OF BETAINE PHOSPHATE PHOSPHITE SOLID-SOLUTIONS/

The solid solution of ferroelectric betaine phosphite and antiferroele ctric betaine phosphate shows an interesting phase diagram with a tran sition from a high temperature prototype phase to a common nonpolar an tiferrodistortive phase followed towards lower temperatures by transit ions into ferroelectric, antiferroelectric or orientaional glass phase s in dependence on its composition. Using magnetic resonance technique s such as electron nuclear double resonance (ENDOR) and electron spin- lattice relaxation measurements we are able to show that an intermedia te phase exists between the antiferrodistortive and the orientational glass phase at intermediate compositions. This new phase shows a regul ar proton order within the phosphate-phosphite chains and is supposed to be of quasiferroic or clusterlike nature.