Georgi Nadjakov (also spelled Georgi Nadzhakov or Nadjakov; Georges Nadjakoff) () (26 December 1896 – 24 February 1981) was a

Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

. He was a corresponding member of the

Göttingen Academy of Sciences Göttingen (, ; ; ) is a university city in Lower Saxony, central Germany, the capital of the eponymous district. The River Leine runs through it. According to the 2022 German census, the population of Göttingen was 124,548. Overview The ...

(1940) in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, member of the

Bulgarian Academy of Sciences The Bulgarian Academy of Sciences (abbreviated BAS; , ''Bŭlgarska akademiya na naukite'', abbreviated БАН) is the National Academy of Bulgaria, established in 1869. The Academy, with headquarters in Sofia, is autonomous and consists of a S ...

(1945) and member of the Russian Academy of Sciences (1958).

Sofia University Sofia University "St. Kliment Ohridski" () is a public university, public research university in Sofia, Bulgaria. It is the oldest institution of higher education in Bulgaria. Founded on 1 October 1888, the edifice of the university was constr ...

sent him to specialize in the laboratories of

Paul Langevin Paul Langevin (23 January 1872 – 19 December 1946) was a French physicist who developed Langevin dynamics and the Langevin equation. He was one of the founders of the '' Comité de vigilance des intellectuels antifascistes'', an anti-fascist ...

and

Marie Curie Maria Salomea Skłodowska-Curie (; ; 7 November 1867 – 4 July 1934), known simply as Marie Curie ( ; ), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity. She was List of female ...

in Paris, where he investigated

photoelectricity The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physic ...

for one year. Georgi Nadjakov experimentally investigated photoconducting properties of

sulphur Sulfur (American spelling and the preferred IUPAC name) or sulphur (English in the Commonwealth of Nations, Commonwealth spelling) is a chemical element; it has Symbol (chemistry), symbol S and atomic number 16. It is abundance of the chemical ...

. He prepared the permanent photoelectret state of matter for the first time and published his paper in 1937 and 1938. He called the

electret An electret (formed as a portmanteau of ''electr-'' from "electricity" and ''-et'' from "magnet") is a dielectric material that has a quasi-permanent electrical polarisation. An electret has internal and external electric fields, and is the ele ...

discovered by Mototaro Eguchi in 1919, thermoelectret and the electret discovered by him in 1937, photoelectret.
Photoelectrets were the most notable achievement of Georgi Nadjakov. Its practical application led to the invention of the

photocopier A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers ...

Chester Carlson Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington. Carlson invented electrophotography (now xerography, meaning "dry writing"), producing a dry ...

some years later. Since 1958 Nadjakov had been a member of the Pugwash Movement of Scientists for Peace.

Honours

* Nadjakov Glacier on

Graham Land Graham Land is the portion of the Antarctic Peninsula that lies north of a line joining Cape Jeremy and Cape Agassiz. This description of Graham Land is consistent with the 1964 agreement between the British Antarctic Place-names Committee ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

is named after Georgi Nadjakov. * Institute of Solid State Physics is since 1982 known as Georgi Nadjakov Institute of Solid State Physics. Its predecessor was founded by Georgi Nadjakov in 1946. * The study of Georgy Nadjakov is a Historic Site of the European Physical Society since 23 May 2014.

References

External links

Academician George Stefanov Nadjakov
on the site of the Institute of Solid State Physics at the

Institute of Solid State Physics

External links

* * 1896 births 1981 deaths Members of the Bulgarian Academy of Sciences 20th-century Bulgarian physicists People from Dupnitsa Rectors of Sofia University Burials at Central Sofia Cemetery {{physicist-stub