The replacement of La by Pr, in La1-xPrxGaO3 solid-solution crystals, led to a decrease in spontaneous strain. Six possible twin states of the m3mFmmm species existed in the orthorhombic phase. The distorted perovskite unit cell became pseudo-tetragonal at x = 0.51. This led to a degeneracy to 3 twin states (m3mF4/mmm species). The (110) and (112) reflection twins, and axial twins with compositional planes close to (211) (S-walls), were identified at x-values of 0.05, 0.10 and 0.30. All of the observed twins were characteristic of crystals having a GdFeO3-type perovskite-like structure. It was shown that the orientation of the S-walls did not depend upon the La/Pr ratio when x was less than 0.3. It varied strongly for x-values ranging from 0.3 to 0.8. The tilt angle between 2 twin states across the twin boundary in (La,Pr)GaO3 was smaller than that in pure LaGaO3 or PrGaO3.

Domain Structure in (La,Pr)GaO3 Solid Solutions. D.I.Savytskii, L.O.Vasylechko, M.Berkowski, J.Fink-Finowicki, R.Aleksiyko, P.Byszewski, A.O.Matkovskii: Ferroelectrics, 2001, 254[1-4], 121-34