Crystallography and Crystal Defects. Anthony Kelly

term u‐axis here should not be confused with the u in the nomenclature [uvw] introduced in Section 1.2 for vectors and is in deference to Georges Friedel who chose this nomenclature when describing Miller−Bravais indices for planes in hexagonal and trigonal materials [7]. Friedel chose a nomenclature for planes and vectors which did not use the {hkl} and 〈uvw〉 notations in familiar use today [3].

      6 6 The symbol || means ‘parallel to’.

      7 7 The relationship between the two cells used in Figures 2.16 and 2.17 is shown in Figure A4.2a, where general methods of transforming the indices of planes and directions, when different unit cells are chosen for the same crystal, are considered.

      8 8 The 230 space groups were established in the late 1880s and early 1890s through the work of Evgraf Stepanovich Fedorov (1853−1919) and Arthur Moritz Schoenflies (1853−1928). An account of how these two scientists arrived at the definitive set of space groups is given in [9], available as a free online version at https://www.iucr.org/publ/50yearsofxraydiffraction.