MEASUREMENT OF LOCAL VARIATIONS IN SPACING AND ORIENTATION OF LATTICE PLANE OF SYNTHETIC QUARTZ

Local variations in spacing and orientation of lattice plane (0110) of quartz in Y-cut plates cut from synthetic crystals were determined with high accuracy from X-ray topographs taken successively at various angular positions around the Bragg position using the double crystal arrangement of parallel setting. The lattice spacing varies with the growth sectors of the crystal in the range of 0 < Δd/d < 1.5 × 10-5 (d is the lattice spacing and Δd is the lattice spacing variation) except the seed area. The orientation of the lattice plane varies by a few seconds of arc over the whole Y-plates in characteristics ways. The contents of impurities A1, Fe and Na in each growth sector were analyzed and related with the lattice spacing variation. The variation in the A1 and Na concentrations corresponds well with that in the lattice spacing. From the comparison of the variation both in the spacing and orientation of the lattice plane, the existence of the internal stress is deduced, which arises from the cell dimension difference among various parts of the crystal. The effect of the internal stress on the spacing and orientation of the lattice plane is discussed qualitatively. © 1979.