Georges Friedel (19 July 1865 – 11 December 1933) was a French

mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

and crystallographer.

Life

Georges was the son of the chemist

Charles Friedel Charles Friedel (; 12 March 1832 – 20 April 1899) was a French chemist and Mineralogy, mineralogist. Life A native of Strasbourg, France, he was a student of Louis Pasteur at the University of Paris, Sorbonne. In 1876, he became a professor of ...

. Georges' grandfather was Louis Georges Duvernoy who held the chair in

comparative anatomy Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species). The science began in the classical era, continuing in t ...

from 1850 to 1855 at the

Muséum national d'histoire naturelle The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...

. Georges studied at the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

in Paris and the École Nationale des Mines in

St. Etienne ST, St, or St. may refer to: Arts and entertainment * Stanza, in poetry * Suicidal Tendencies, an American heavy metal/hardcore punk band * Star Trek, a science-fiction media franchise * Summa Theologica, a compendium of Catholic philosophy ...

, and was a student of François Ernest Mallard. In 1893 he obtained a professorship at the École Nationale des Mines, the director of which he would later become. After the

First World War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, he returned as a professor at the

University of Strasbourg The University of Strasbourg (french: Université de Strasbourg, Unistra) is a public research university located in Strasbourg, Alsace, France, with over 52,000 students and 3,300 researchers. The French university traces its history to the ea ...

Alsace Alsace (, ; ; Low Alemannic German/ gsw-FR, Elsàss ; german: Elsass ; la, Alsatia) is a cultural region and a territorial collectivity in eastern France, on the west bank of the upper Rhine next to Germany and Switzerland. In 2020, it had ...

. Due to ill health, he took early retirement in 1930, and died in 1933. He was married with five children.

Scientific works

Like his teacher Mallard, Friedel concerned himself with the theories of

Auguste Bravais Auguste Bravais (; 23 August 1811, Annonay, Ardèche – 30 March 1863, Le Chesnay, France) was a French physicist known for his work in crystallography, the conception of Bravais lattices, and the formulation of Bravais law. Bravais also studie ...

, the founder of

crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The wor ...

. Friedel was able to demonstrate the theoretical ideas of Bravais (the

Bravais lattice In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by : \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n_ ...

) with the help of

x-ray diffraction X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

experiments on

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s, and so provide the physical basis therefore. One of his most important discoveries was the

law Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vario ...

that now bears his name.

Friedel's salt

In 1897, Georges Friedel synthesised and identified calcium chloroaluminate which received his name. Georges Friedel also synthesised

calcium aluminate Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...

in 1903 in the framework of his work on the

macle {{no footnotes, date=April 2009 Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal (such as chiastolite). It is crystallographic twin according to the spinel twin law and is seen in octahedral crysta ...

s theory.

Mesomorphic states of matter

The presumption that solid and liquid are adjacent states of matter was undercut by

Friedrich Reinitzer Friedrich Richard Reinitzer (25 February 1857 in Prague – 16 February 1927 in Graz) was an Austrian botanist and chemist. In late 1880s, experimenting with cholesteryl benzoate, he discovered properties of liquid crystals (named later by Otto ...

in 1888 when he noted a cloudy

mesophase In chemistry and chemical physics, a mesophase is a state of matter intermediate between liquid and solid. Gelatin is a common example of a partially ordered structure in a mesophase. Further, biological structures such as the lipid bilayers of cel ...

cholesteryl benzoate Cholesteryl benzoate, also called 5-cholesten-3-yl benzoate, is an organic chemical, an ester of cholesterol and benzoic acid. It is a liquid crystal material forming cholesteric liquid crystals with helical structure. It can be used with choleste ...

between 145.5 °C and 178.5 °C. The subject was taken up in Germany, and in 1907 also in France by Georges Friedel and

François Grandjean François () is a French masculine given name and surname, equivalent to the English name Francis. People with the given name * Francis I of France, King of France (), known as "the Father and Restorer of Letters" * Francis II of France, King ...

, as they described the "focal conic liquid". Friedel contributed his ''Mesomorphic States of Matter'' to the Annales des Physiques in 1922. This two-hundred-page work established much of the current terminology in

physics. First, the ''

nematic Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. The ...

phase'' he characterized as having microscopic threads (these threads are today interpreted as

disclination In crystallography, a disclination is a line defect in which rotational symmetry is violated. In analogy with dislocations in crystals, the term, ''disinclination'', for liquid crystals first used by Frederick Charles Frank and since then has been m ...

s in the director-field in the mesophase). Second, Friedel coined the term ''

smectic Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. The ...

phase'' for a layered mesophase having the structure of neat soap. Third, Friedel use the term ''

cholesteric A cholesteric liquid-crystal display (ChLCD) is a display containing a liquid crystal with a helical structure and which is therefore chiral. Cholesteric liquid crystals are also known as '' chiral nematic liquid crystals''. They organize in layer ...

phase'' for materials like

, and noted that such mesophases "involve strong twists around a direction normal to the positive

optical axis An optical axis is a line along which there is some degree of rotational symmetry in an optical system such as a camera lens, microscope or telescopic sight. The optical axis is an imaginary line that defines the path along which light propagat ...

".David Dunmur and Tim Sluckin (2011) ''Soap, science, and flat-screen TVs: a history of liquid crystals''. pp. 80–90,

Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...

Scientists have followed Friedel's classification and the term ''

'' for the intermediate states has also been adopted from him. He was of the conviction that the term

liquid crystal Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. T ...

did not bear scrutiny. Indeed, :The liquid crystals were not crystals at all, but peculiar liquids with some hint of solid properties. In 1931 Georges published, with his son Edmond Friedel, the results of their

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

studies: "The physical properties of the mesophases in general, and their importance in a scheme of classification."''Zeitschrift für Kristallographie'' 79:1–60.

Important publications

* 1904: ''Groupements cristallins'' * 1907: ''Etudes sur les lois de Bravais'' * 1922: ''Les états mésomorphes de la matiere''

References

External links

* François Grandjean (1935
George Friedel
''Bulletin de la Société Française de Minéralogie'', weblink from ''Annales des Mines'' (French). * Maurice Kleman (2005
Georges Friedel et "Les phases mésomorphes de la matière".
weblink to ''Institut de Minéralogie et de Physique des Milieux Condensés'' (French). {{DEFAULTSORT:Friedel, Georges 1865 births 1933 deaths Scientists from Mulhouse École Polytechnique alumni People from Alsace-Lorraine Crystallographers Liquid crystals French mineralogists