Open AccessThe variation with temperature of the intensity of reflection of X-rays from quartz and its bearing on the crystal structure
Publication year - 1925
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1925.0041
Subject(s) - perpendicular , symmetry (geometry) , crystal (programming language) , reflection (computer programming) , crystallography , intensity (physics) , bragg's law , unit (ring theory) , crystal structure , plane (geometry) , quartz , optics , physics , materials science , geometry , diffraction , chemistry , mathematics , computer science , composite material , programming language , mathematics education
Since the appearance of Sir William Bragg’s first work on the structure of martz (these ‘Proceedings,’ A, vol. 89, p. 595 (1914)) this mineral has been the subject of many investigations. It has lent itself very well to study by the older crystallographic methods, by which, from symmetry considerations, has been placed in the trapezohedral class of the trigonal system,i. e ., it exhibits trigonal symmetry about one (c ) axis and digonal symmetry about ree others, lying symmetrically in a plane perpendicular to the first and intersecting in it. Two enantiomorphous forms were found to exist. Investigation by the X-ray spectrometer method enabled Bragg to give the dimensions of the unit triangular prismatic cell asa = 4·89 Å. U. and = 5·375 Å. U., whilst density considerations clearly indicated that three olecules were associated with such a unit cell. It was also shown that the three molecules were associated with the unit cell in such a way that planes of equal weight occurred ato ,c /3, 2c /3,c , etc., along the verticalc axis.