Imaging dislocations in ice

Abstract

Three techniques have been used to study dislocations in ice: etch pitting-replication, transmission electron microscopy, and X-ray topography (XT). It is shown that, because ice is a weak absorber of X-rays and can be produced with a low dislocation density, allowing relatively thick specimens to be studied, the most useful technique is XT. The observations that have been made with conventional XT are briefly outlined. However, the introduction of high-intensity synchrotron radiation, with its concomitant short exposure times, showed that images obtained through conventional XT observations were of dislocations that had undergone recovery. The important dynamic observations and measurements that have been made using synchrotron X-ray topography are presented. Dynamic synchrotron X-ray topography observations of ice single crystals undergoing deformation in situ have shown that slip mainly occurs by the movement of screw and 60 degrees (1/3) [1120] dislocations on the basal plane, although non-basal slip by edge dislocations can also occur. The operation of Frank-Read and other dislocation multiplication sources have been clearly demonstrated and dislocation velocities have been measured. In contrast, in polycrystals, dislocation generation occurred at grain boundaries where there are stress concentrations before lattice dislocation generation mechanisms operate. Faulted dislocation loops have been determined to be mainly interstitial in both polycrystals and single crystals.

Impurity Analysis and Microstructure Along the Climatic Transition From MIS 6 Into 5e in the EDML Ice Core Using Cryo-Raman Microscopy

“…However, most of the micro-inclusions were located in the grain interiors. Several EDX studies (Cullen and Baker, 2001; Barnes et al, 2002;Baker, 2003;Barnes, 2003;Iliescu and Baker, 2008) reported traces of sodium, chlorine and sulfur forming filaments at the sublimed ice surface. Some of the filaments grew at sites where grain boundaries and triple junctions intersected the surface.…”

Growth of multilayer ice films and the formation of cubic ice imaged with STM

“…8 Still, the nanometer-thickness range has eluded examination by microscopy, and important questions about multilayer ice growth remain, such as, e.g., why cubic ice often forms instead of hexagonal ice. The extreme sensitivity of ice to electron beam damage severely hampers the use of electron microscopy, 9,10 and x-ray topography with nanometer resolution has not been reported. 10 STM has not yet been applied to ice multilayer growth, perhaps because of the perception that the insulating character of ice prevents maintaining an electric current high enough to sustain the imaging process or that these currents will damage the film.…”

“…The extreme sensitivity of ice to electron beam damage severely hampers the use of electron microscopy, 9,10 and x-ray topography with nanometer resolution has not been reported. 10 STM has not yet been applied to ice multilayer growth, perhaps because of the perception that the insulating character of ice prevents maintaining an electric current high enough to sustain the imaging process or that these currents will damage the film. Here, we report how these constraints can be overcome and how STM can be used to gain insights into how ice grows on Pt͑111͒.…”

Методы Рентгеновской Дифракционной Топографии (О Б З О Р)

“…Востребованность рентгеновской топографии вызвала появление большого количества обзоров и монографий (например, [2][3][4][5][6][7][8][9][10][11][12][13][14][15] и [16,17], соответственно). Однако часть из этих обзоров -" возрастные" [2,3,5,7], часть посвящена конкретной узкой области применения рентгеновской топографии [4,6,8,[9][10][11][12]14].…”