Early Work on X-ray Diffraction in the California Institute of Technology

Abstract

The first crystal-structure determinations to be made in the United States were those of Hull, the determination of the structure of some metals by the powder method, and of Burdick and Ellis. The work of Burdick and Ellis was done in Pasadena, in the Gates Laboratory of Chemistry (constructed in 1916) of the California Institute of Technology, which at that time was called the Throop College of Technology. C. Lalor Burdick, after obtaining his M.S. degree in the Massachusetts Institute of Technology in 1914 and his Ph.D. degree in Basel in 1915, had spent a few months with W. H. Bragg in University College, London, learning the technique of using the X-ray ionization spectrometer. In 1916 he built an ionization spectrometer in the Massachusetts Institute of Technology, and then moved to Pasadena, where he built a second one. He and James H. Ellis, who was Research Professor of Physical Chemistry in the California Institute of Technology, then carried out an X-ray investigation of a single crystal of chalcopyrite, 8 mm in diameter. Their paper, published in J. Am. Chem. Soc. 39, 2518 (1917), was entitled ‘The Crystal Structure of Chalcopyrite Determined by X-rays’. The integrated intensities of 13 forms were measured. The structure was reported to be a superstructure of the sphalerite structure (chalcopyrite is CuFeS2). The reported structure was almost but not quite right; fifteen years later it was found that the distribution of Cu and Fe among the Zn positions of the sphalerite structure is somewhat different from that proposed by Burdick and Ellis. A paper on the structure of silicon carbide (cubic form) by Burdick and E. A. Owen (Professor of Physics in University College of North Wales, 1926–54, now Emeritus) was published in J. Am. Chem. Soc. 40, 1749 (1918). It describes work done by them in London and continued by Burdick in the Massachusetts Institute of Technology.