No abstract

Tlie method of "induced growth striations" was applied to the hydrothermal growth of quartz crystals. Striations were due to a periodical modulation of the growth t e r i i p -rature induced arid investigated by nieans of the X-ray Lang topography and plane wave reflection topography. The results show that the X-ray topographic methods are a sensitive tool for the characterization of the growth striations, which are produced generallj by A1 impurities. The application of the method of induced growth striations to quartz crystals and the characterization of these crystals with optical and X-ray topographical methods allow a deeper Understanding of the crystal growth behaviour.

Several possibilities for the determination of relative lattice parameter changes and for the absolute measurement of lattice parameters are discussed. Special attention has been given to a measuring device for the high-precision lattice parameter determination according to the BOND method. This device allows to determine the lattice parameters with a relative accuracy of 2 x lo-?. As a n example the methods discussed are applied to the investigation of a smoky coloured quartz crystal plate and the results obtained by them were compared.Es werden verschiedene Moglichkeiten zur Bestimmung der relativen Gitterkonstanteniinderung und zur Absolutmessung von Gitterkonstanten diskutiert. Besonders wird auf eine Anordnung zur hochprazisen Gitterkonstantenmessung auf der Grundlage der BOND-Methode eingegangen. Mit dieser Anordnung konnen die Gitterkonstanten mit einer relativen Genauigkeit bis zu 2 x lo-' bestimrnt werden. Als Beispiel werden die diskutierteri Mcthoden an einem rauchverfiirbten Quarzkristall angewendet und die gewonnenen Ergebnisse verglichen.

Realstrukturuntersuchungen von hydrothermal auf kleinen Rhomboederflachen gewachsenen Quarzeinkristallen')Es wurden optische, atztechnische und rontgenographische Untersuchungen an Quarzkristallen, die auf Rhomboederkeimen gewachsen waren, durchgefuhrt. Durch Verfarbungsversuche wurde in Ubereinstimmung mit der Literatur festgestellt, dalj sich Aluminiumfremdatome verstarkt in den Wachstumssektor der kleinen Rhomboederflache einbauen.

A qualitative and quantitative study of the contrast formation in X‐ray plane wave topographs of quartz plates with induced growth striations is presented. Contrast distributions are calculated by means of a simple local application of the dynamical theory of the X‐ray diffraction from the perfect crystal and using a mathematical model of the lattice deformation according to the isotropic theory of elasticity. A good agreement between calculations and experimental results can be stated.