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Graphical Determination of Hexagonal and Tetragonal Crystal Structures from X-Ray Data

1921; American Institute of Physics; Volume: 17; Issue: 5 Linguagem: Inglês

10.1103/physrev.17.549

1536-6065

Albert W. Hull, Wheeler P. Davey,

Boron and Carbon Nanomaterials Research

Graphic Method for Interpreting X-Ray Patterns of Powders.---For each type of lattice the logarithms of the theoretical spacings of the different planes are plotted as functions of the axial ratio. Six such plots are reproduced, three for the hexagonal and three for the tetragonal system. By plotting the logarithms of the observed spacings on the edge of a strip of paper, this may be fitted by trial to the theoretical plot; the axial ratio and type of lattice being thus found in a few minutes.Crystal Structure of Zn, Cd, In.---As examples three complete analyses are given. Zinc is shown to be a hexagonal close packed assemblage of prolate spheroids. The axial ratio is 1.860 and the side of the unit triangle 2.760 \AA{}. Cadmium shows a structure like that of Zn, with axial ratio 1.89 and elementary triangle 2.980 \AA{}. Indium shows a structure nearly like Al (cubic close-packed), viz., a tetragonal close packed arrangement of prolate spheroids, with axial ratio 1.06 and a unit square of 4.58 \AA{}.