Georg Wulff, Georgy Wulff or Yuri Viktorovich Vulf () (22 June 1863,

Nizhyn Nizhyn (, ; ) is a city located in Chernihiv Oblast of northern Ukraine along the Oster River. The city is located north-east of the national capital Kyiv. Nizhyn serves as the capital city, administrative center of Nizhyn Raion. It hosts the ...

(

Russian Empire The Russian Empire was an empire that spanned most of northern Eurasia from its establishment in November 1721 until the proclamation of the Russian Republic in September 1917. At its height in the late 19th century, it covered about , roughl ...

, now

Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...

) – 25 December 1925,

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

) was a pioneer Russian

crystallographer A crystallographer is a type of scientist who practices crystallography, in other words, who studies crystals. Career paths The work of crystallographers spans several academic disciplines, including the life sciences, chemistry, physics, and m ...

Biography

Wulff was born in Nizhyn, Chernigov province where his mother Lydia was daughter of teacher E. V. Gudim. His father Viktor Konstantinovich Vulf was a literature teacher at the 6th Warsaw Gymnasium. He grew up in Warsaw and graduated from the 6th Warsaw Gymnasium in 1880. He then went to the Imperial Warsaw University to study natural sciences. He studied under crystallographer A. E. Lagorio, and physicists N. G. Egorov and P. A. Zilov. In the third year, he studied the electrical properties of quartz for which he received a gold medal. In his fourth year he was assisting lectures of professor Zilov. He began to study the relationship of crystal structure and optical properties and in 1888 he published a paper on the "theory of rotatory polarization". He then went to St. Petersburg University working with E.S. Fedorov. In 1889 he went to Munich to study with

Paul Heinrich von Groth Paul Heinrich Ritter von Groth (23 June 1843 – 2 December 1927) was a German mineralogist. His most important contribution to science was his systematic classification of minerals based on their chemical compositions and crystal structures. Bi ...

. He also attended classes by Leonard Zonke. He also went to Paris and studied under

Marie Alfred Cornu Marie Alfred Cornu (; 6 March 1841 – 12 April 1902) was a French physicist and professor of École polytechnique. The French generally refer to him as Alfred Cornu. The Cornu spiral, a graphical device for the computation of light intensities ...

. While in Paris he married Vera Vasilyevna Yakunchikova. He returned to Warsaw to defend his master's thesis in 1892 on pseudosymmetric crystals. He then became a privatdozent at Warsaw University and lectured on mineralogy and crystallography. In 1897 he joined the Imperial Kazan University but returned to Warsaw in 1899. In 1907 he was invited to Moscow University by V. I. Vernadsky. He taught crystallography also at the

Shanyavsky Moscow City People's University Shanyavsky Moscow City People's University () was a university in Moscow that was founded in 1908 with funds from the gold mining philanthropist Alfons Shanyavsky. The university was nationalized in 1918 after the Russian revolution and merged in ...

. He also collaborated with P. N. Lebedev. In 1911 he left Moscow University along with other professors in protest of

Lev Casso Lev Aristidovich Kasso (1865–1914) was an Imperial Russian politician. A Professor of Civil Law by education, he served as Imperial Minister of Education from 1910 through 1914 in the Stolypin and Kokovtsov governments. The state's univ ...

. During World War I, Wulff helped develop new X-ray equipment. In 1917 he was restored to Moscow University and from 1922 he headed the Institute of Physics and Crystallography.

Scientific contributions

Wulff studied crystal growth processes and modified Curie's principle on the minimization of surface energy. Now called the Gibbs-Curie-Wulff principle it states that the growth rate of the faces of a crystal are proportional to the specific surface energies of the faces. This is further extended by his idea of Wulff vectors and the

Wulff construction The Wulff construction is a method to determine the equilibrium shape of a droplet or crystal of fixed volume inside a separate phase (usually its saturated solution or vapor). Energy minimization arguments are used to show that certain crystal ...

. He also introduced a stereoscoping projection method using what is called the

Wulff net In mathematics, a stereographic projection is a perspective projection of the sphere, through a specific point on the sphere (the ''pole'' or ''center of projection''), onto a plane (the ''projection plane'') perpendicular to the diameter thr ...

. Wulff was one of the first to experiment with

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

. He developed a relationship in X-ray diffraction (''nλ = 2d sin θ'') which was also found independently by the Bragg father and son duo in 1913 and sometimes called the Bragg–Wulff equation. The mineral

wulffite Wulffite is an alkali copper sulfate mineral with the chemical formula Potassium, K3Sodium, NaCopper, Cu4Oxygen, O2(Sulfur, SOxygen, O4)4, in the sulfate category of minerals. It was recently discovered in Kamchatka, Russia at the Tolbachik volcan ...

are named after him.

References

{{DEFAULTSORT:Wulff, George 1863 births 1925 deaths Crystallographers University of Warsaw alumni 19th-century physicists from the Russian Empire Academic staff of the University of Warsaw