The photoelastic (piezo-optic) property of the ferroelectric crystals
lithium heptagermanate Li2Ge7O15 (LGO) were studied in para-and ferro-
electric phases for different orientations. The value of stress optica
l coefficient C-ijk (in Brewsters) along a, b, c-axes were determined
at RT (291 K) and 278 K and were compared with some other ferroelectri
c systems like Rochelle-salt (RS), potassium dihydrogen phosphate (KDP
) and ammonium dihydrogen phosphate (ADP). Large photoelastic coeffici
ents and other properties like good mechanical strength, or transition
temperature close to RT and stability in ambient environment favour L
GO as a potential candidate for photoelastic applications.