Use of X-Rays for Determining the Orientation of Quartz Crystals

The Use of X-Rays for Determining the Orientation of Quartz Crystals T By W. L. B O N D And E. J. A R M S T R O N G HIS paper is one of a series by the Crystal Research Group on the manufacture of quartz oscillator plates. Certain sections of it which are not original, but rather adaptations of text book material to the present problem, are included for purposes of completeness and for the convenience of those readers whose knowledge of the crystallographic literature may be limited. 3 . 1 PRODUCTION OF X - R A Y S FOR QUARTZ CRYSTAL X - R A Y WORK X-rays are produced when electrons strike a metal target at high velocity. The wave-length of X-rays given off from an X-ray tube varies from the longest which can pass through the X-ray tube window to the shortest that can be produced from the given target by the applied peak voltage. By analogy to the visible spectrum this is referred to as "white" radiation. For each different metal, however, there are characteristic radiations of certain wave-lengths whose intensity markedly exceeds those of other wavelengths (Fig. 3.1). The strongest of these characteristic radiations is known as the KA, the next strongest (generally half as strong and of slightly longer wave-length) as A'a2 and the third strongest (shorter in wave-length than KAI) is A"/3. The higher the atomic number of the target, the shorter will be the wave-length of the characteristic radiation. Therefore higher voltages will be required to excite the characteristic radiation from the heavier metals.