Stacking faults in BeO crystals

Abstract

A complex stacking-fault structure was revealed in a flux-grown BeO crystal, with X-ray topographic images as well as characteristic interference fringes around the stacking-fault image. Coplanar with the stacking fault are a number of dislocations of various (unidentified) Burgers vectors, all probably having a common origin during crystal growth.The crystal structure of ~-beryilia is hexagonal closestpacked (wurtzite type) at room temperature. The hightemperature form (fl-beryllia) is tetragonal (Smith, Cline & Austerman, 1965). Evidence for the presence ofacubic form has not been reported. Therefore, the stackingfault energy for BeO seems to be high and stacking faults ha,re not been found in BeO crystals. The purpose of the present note is to give evidence of stacking faults in ~-beryllia.The stacking faults were observed by X-ray diffraction topography. The crystal studied was grown from LizMoO4-MoO3 (Austerman, 1964)

In situ x-ray topography of silicon carbide during crystal growth by sublimation method

“…A real-time imaging system consisting of an x-ray sensing camera tube facilitated the in situ observation of the topographs. 4 Synchrotron radiation with high intensity and good collimation as well as continuous spectrum is suitable for in situ topography. Extensive studies by in situ white-beam x-ray topography have provided intuition about grain movement.…”

Ultra-high vacuum heating camera for in situ synchrotron radiation X-ray topographic studies

“…Also, in situ X-ray topographic studies have in their favour, owing to the low X-ray absorption by materials, the ability to allow the observation of phenomena in the bulk, i.e. in their natural surroundings (Chikawa, 1974). With the coming of synchrotron Xray radiation, topographic studies in real time have now become easier (Sauvage & Petroff, 1980;Queisser, Hartmann & Hagen, 1981).…”

Characteristics of a channel plate as an image intensifier for X-ray topography

“…In order to take X-ray topographs so rapidly that imperfections in crystals may be observed almost in real time, two kinds of techniques have been developed so far: one is to use the intense X-ray source and a vidicon tube with good resolution (Chikawa & Fujimoto, 1968;Chester & Koch, 1969;Rozgonyi, Haszko & Statile, 1970;Chikawa, Fujimoto & Abe, 1972;Chikawa, 1974), and the other is to use a usual source but make the detecting system sensitive with various kinds of image intensifying tubes, where electron scanning is used (Reifsnider & Green, 1968;Lang & Reifsnider, 1969;Meieran, Landre & O'Hara, 1969;Meieran, 1971;Hashizume, Kohra, Yamaguchi & Kinoshita, 1971 ;Kozaki, Hashizume & Kohra, 1972).…”