Lattice-parameter determination of quartz by means of the /spl Omega/-scan method

The lattice parameters of quartz depend on the crystal quality and influence the accuracy of the X-ray orientation determination of resonators. Therefore, they should be known better than 20 ppm. Using the /spl Omega/-scan method, the lattice parameters can be determined together with the orientation, measuring at least two additional reflections. Preliminary measurements on SC-cut quartz blanks were performed with standard deviations of the lattice parameters of /spl les/6 ppm in a measuring time of about 3 min. The evaluation of the peak position must consider its systematic error. The total error is estimated to be <10 ppm. The measuring procedure can also be applied to IT-cut, FC-cut and AT-cut quartz blanks and, moreover, to any single crystal.