A comparison of laser-induced twinning of quartz based on characteristics and supplier

AT-cut samples were irradiated at room temperature using a focused CO₂ laser. For both swept and unswept material, it is found that irradiance levels necessary for twin nucleation did not correlate with α(3500 cm^-1) in the range 0.028<α<0.189. Surface twins, forming on AT-cut plates, remained approximately the size of the irradiated area. After repeated exposures, the twinned area formed figures resembling the calculated ferrobielastic stress diagram for AT-cuts. Twinned areas are more irregular in high etch channel regions. SC-cut twins showed a tendency to extend, in a direction close to the z-axis, towards the edge of the sample in only one direction. This result differs with the more symmetric stress diagram calculated for the SC-cut