In La1-xNdxGaO3 crystals, La-Nd substitution led to a decrease in spontaneous strain. For a composition with x = 0.32, the 6 possible twin states of the orthorhombic phase (m3mFmmm) could degenerate into 3 twin states, which were inherent in the m3mF4/mmm species, when a distorted perovskite pseudo-cell became tetragonal. The {110} and {112} reflection twins, and axial twins with compositional planes close to (211) – S-walls - were identified in La1-xNdxGaO3 when x was equal to 0.07, 0.12 or 0.20. All of the observed twins were typical of crystals having the GdFeO3-type structure. It was shown that, for x-values of less than 0.2 or greater than 0.5, the orientations of the S-walls depended weakly upon the La/Nd ratio. For x-values of between 0.2 and 0.5, they depended strongly upon the solid solution composition. The tilt angle between 2 twin states across a twin boundary, when x was less than 0.6, was smaller than that between 2 twins in pure LaGaO3 or NdGaO3.

Twin Structure of (La,Nd)GaO3 Solid Solutions. D.I.Savytskii, M.Berkowski, L.O.Vasylechko, J.Fink-Finowicki, A.O.Matkovskii: Crystal Research and Technology, 2000, 35[1], 53-63