Twin structure of (La, Nd)GaO3 solid solutions

For La1-xNdxGaO3 crystals the La-Nd substitution leads to decrease of spont aneous strains and for composition with x approximate to 0.32 the six possi ble twin states of orthorhombic phase (m3mFmmm) may be degenerated in three twin states inhered in m3mF4/mmm species when a distorted perovskite pseud ocell becomes tetragonal. The {110} and {112} reflection twins and axial tw ins with compositional planes close to (211)and(21 (1) over bar) (S-walls) were identified in La1-xNdxGaO3 (x=0.07, 0.12, 0.20) solid solutions crysta ls. All observed twins are typical for crystals with GdFeO3 type perovskite -like structure. It has been shown that for x less than or equal to 0.2 and x greater than or equal to 0.5 orientations of S-walls weakly depend on La /Nd ratio, whereas in the range of 0.2<x<0.5 they depend strongly on the so lid solution composition. The tilt angle between two twin states across twi n boundary in La1-xNdxGaO3 (x<0.6) solid solutions is smaller than that bet ween two twins in pure LaGaO3 or NdGaO3.