International Union of Crystallography
Formation1948; 76 years ago (1948)
Region served
Official language
Parent organization
International Council for Science

The International Union of Crystallography (IUCr) is an organisation devoted to the international promotion and coordination of the science of crystallography. The IUCr is a member of the International Council for Science (ICSU).


The objectives of the IUCr are to promote international cooperation in crystallography and to contribute to all aspects of crystallography, to promote international publication of crystallographic research, to facilitate standardization of methods, units, nomenclatures and symbols, and to form a focus for the relations of crystallography to other sciences.

The IUCr fulfils these objectives by publishing in print and electronically primary scientific journals through the Acta Crystallographica journal series, as well as Journal of Applied Crystallography, Journal of Synchrotron Radiation, IUCrJ,[1] the series of reference volumes International Tables for Crystallography,[2] distributing the quarterly IUCr Newsletter,[3] maintaining the online World Directory/Database of Crystallographers,[4] awarding the Ewald Prize[5] and organising the triennial Congress and General Assembly.


[6][7] In 1944 the yearly meeting of the X-ray Analysis Group (XRAG) of the UK Institute of Physics was held in Oxford, and the distinguished German crystallographer Paul Peter Ewald, who then taught at Queen's University Belfast, was invited to give the evening lecture. In it he gave a historical survey of some of the stages in the evolution of X-ray crystallography and ended with a strong plea for the formation of an international society or union which would represent, and unify publication for, the new science. This idea was followed up by the British crystallographers, and particularly by Sir Lawrence Bragg, the Chairman of XRAG. In June 1946, within a year of the termination of fighting in WWII, he arranged for an international meeting of crystallographers in London which was attended by some 120 scientists from most of the allied countries.[8] In that London meeting Ewald was elected Chairman of the Provisional International Crystallographic Committee, which put into action the decision to form the International Union of Crystallography.[6]


Sir Lawrence Bragg was the first formally elected President of the IUCr,[6] with Ralph Walter Graystone Wyckoff[9] and Arne Westgren [10] as Vice-Presidents. Ewald was elected as 5th President of the IUCr, the 'international society or union' that he had originally conceived, in 1960.[11][12]

IUCr Symmetry notation

The IUCr notation is the notation for the symmetry group adopted by the International Union of Crystallography in 1952. It identifies members of the Wallpaper group with a 4 character name. First it has a P or C for primitive or centered groups. Groups are denoted by a number 1, 2, 3, 4, or 6 for the highest order of symmetry. Groups can have one or two reflections, denoted as vertical mirrors first (horizontal reflection), and horizontal second (vertical reflection). A simple reflection is denoted by an m (mirror), and a glide-reflection is denoted by a g. Place holder 1 denotes an orthogonal direction with no reflections.

See also


  1. ^ "Crystallography Journals Online". Crystallography Journals Online. The International Union of Crystallography.
  2. ^ "International Tables for Crystallography". International Tables for Crystallography. International Union of Crystallography.
  3. ^ "IUCr Newsletter". IUCr Newsletter. The International Union of Crystallography.
  4. ^ "World Directory of Crystallographers". World Directory of Crystallographers. The International Union of Crystallography.
  5. ^ "The Ewald Prize". The Ewald Prize. The International Union of Crystallography.
  6. ^ a b c Kamminga, Harmke (1989). "The International Union of Crystallography: its formation and early development". Acta Crystallogr. A45 (9): 581–601. doi:10.1107/S0108767389003910.
  7. ^ Ewald, Paul P (ed.). "The Consolidation of the New Crystallography". The International Union of Crystallography.
  8. ^ With one very distinguished exception, the German physicist Max von Laue, who won the 1914 Nobel Prize for his discovery of X-ray diffraction in crystals, whose invitation and acceptance required some degree of political and personal courage by both Bragg and von Laue.
  9. ^ "Ralph W. G. Wyckoff 1897-1994," Acta Crystallogr. (1995). A51, 649-650. Accessed online at Archived 2010-11-07 at the Wayback Machine on 3/23/2010
  10. ^ "Obituary: Arne Westgren 1889-1975" (PDF). The International Union of Crystallography.
  11. ^ "(IUCr) Aspects of the History of the IUCr". Retrieved 2023-05-01.
  12. ^ "Previous Executive Committees". Retrieved 2023-05-01.

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