Editing Crystallography (section)

== History and timeline ==
{{Main|Timeline of crystallography}}

Before the 20th century, the study of [[crystal]]s was based on physical measurements of their geometry using a [[goniometer]].<ref>{{Cite journal|date=1915-07-01|title=The Evolution of the Goniometer|journal=Nature|language=en|volume=95|issue=2386|pages=564–565|doi=10.1038/095564a0|bibcode=1915Natur..95..564.|issn=1476-4687|doi-access=free}}</ref> This involved measuring the angles of crystal faces relative to each other and to theoretical reference axes (crystallographic axes), and establishing the [[Symmetry (physics)|symmetry]] of the crystal in question. The position in 3D space of each crystal face is plotted on a [[Stereographic projection|stereographic]] net such as a [[Wulff net]] or [[Lambert azimuthal equal-area projection|Lambert net]]. The [[pole figure|pole]] to each face is plotted on the net. Each point is labelled with its [[Miller index]]. The final plot allows the symmetry of the crystal to be established.<ref>{{Cite journal |last1=Molčanov |first1=Krešimir |last2=Stilinović |first2=Vladimir |date=2014-01-13 |title=Chemical Crystallography before X-ray Diffraction |url=https://onlinelibrary.wiley.com/doi/10.1002/anie.201301319 |journal=Angewandte Chemie International Edition |language=en |volume=53 |issue=3 |pages=638–652 |doi=10.1002/anie.201301319 |pmid=24065378 |issn=1433-7851}}</ref><ref>{{Cite journal |last=Mascarenhas |first=Yvonne Primerano |date=2020-03-02 |title=Crystallography before the Discovery of X-Ray Diffraction |journal=Revista Brasileira de Ensino de Física |language=en |volume=42 |pages=e20190336 |doi=10.1590/1806-9126-RBEF-2019-0336 |issn=1806-1117|doi-access=free }}</ref>

The discovery of [[X-ray]]s and [[electron]]s in the last decade of the 19th century enabled the determination of crystal structures on the atomic scale, which brought about the modern era of crystallography. The first X-ray diffraction experiment was conducted in 1912 by [[Max von Laue]],<ref name="L1912">{{cite journal |vauthors=Friedrich W, Knipping P, von Laue M |date=1912 |title=Interferenz-Erscheinungen bei Röntgenstrahlen |url=https://commons.wikimedia.org/wiki/File:Interferenz-Erscheinungen_bei_Röntgenstrahlen.pdf |journal=Sitzungsberichte der Mathematisch-Physikalischen Classe der Königlich-Bayerischen Akademie der Wissenschaften zu München |volume=1912 |page=303 |trans-work=Interference phenomena in X-rays}}</ref> while electron diffraction was first realized in 1927 in the [[Davisson–Germer experiment]]<ref>{{Cite journal |last1=Davisson |first1=C. |last2=Germer |first2=L. H. |date=1927 |title=The Scattering of Electrons by a Single Crystal of Nickel |url=https://www.nature.com/articles/119558a0 |journal=Nature |language=en |volume=119 |issue=2998 |pages=558–560 |doi=10.1038/119558a0 |bibcode=1927Natur.119..558D |issn=1476-4687}}</ref> and parallel work by [[George Paget Thomson]] and Alexander Reid.<ref>{{Cite journal |last1=Thomson |first1=G. P. |last2=Reid |first2=A. |date=1927 |title=Diffraction of Cathode Rays by a Thin Film |url=https://www.nature.com/articles/119890a0 |journal=Nature |language=en |volume=119 |issue=3007 |pages=890 |doi=10.1038/119890a0 |bibcode=1927Natur.119Q.890T |issn=1476-4687}}</ref> These developed into the two main branches of crystallography, [[X-ray crystallography]] and [[Electron diffraction|electron]] diffraction. The quality and throughput of solving crystal structures greatly improved in the second half of the 20th century, with the developments of customized instruments and [[Phase problem|phasing algorithms]]. Nowadays, crystallography is an [[interdisciplinary field]], supporting theoretical and experimental discoveries in various domains.<ref>{{Cite journal |last1=Brooks-Bartlett |first1=Jonathan C. |last2=Garman |first2=Elspeth F. |date=2015-07-03 |title=The Nobel Science: One Hundred Years of Crystallography |url=https://journals.sagepub.com/doi/full/10.1179/0308018815Z.000000000116 |journal=Interdisciplinary Science Reviews |language=en |volume=40 |issue=3 |pages=244–264 |doi=10.1179/0308018815Z.000000000116 |bibcode=2015ISRv...40..244B |issn=0308-0188}}</ref> Modern-day scientific instruments for crystallography vary from laboratory-sized equipment, such as [[diffractometer]]s and [[electron microscope]]s, to dedicated large facilities, such as [[photoinjector]]s, [[synchrotron light source]]s and [[free-electron laser]]s.