X‐ray topographic study of antiphase domain boundaries in ferroelectric ferroelastic GdDy(MoO4)3 crystals. I. Geometry of antiphase domain boundaries

Antiphase domain boundaries (APB’s) in ferroelastic‐ferroelectric GdDy(MoO4)3 crystals present an unexpected contrast on x‐ray topographic images which leads to introduce a correction vector Δf, in addition to the expected translation vector 1/2(a+b) between two neighboring antiphase domains. The geometry of some APB’s is determined with the help of different traverse topographic images and etch patterns. Emphasis is put on two different geometries which will be studied in more detail in a separate paper.