Laser-induced twinning in ferroelastic Gd₂(MoO₄)₃

Gadolinium molybdate was twinned by irradiating the crystals for a few seconds with a 10.6 μm CO₂ laser. Slit-shaped regions were irradiated to produce localized heating, thereby setting up suitably oriented thermal stresses of sufficient size to induce mechanical twinning. Ferroelastic twin patterns are difficult to control by this method because the required slit orientations are not parallel to domain-wall directions.