Georgi Nadjakov (also spelled Georgi Nadzhakov) ( bg, Георги Наджаков) (26 December 1896 – 24 February 1981) was a

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

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 caus ...

. He became a corresponding member of the

Göttingen Academy of Sciences Göttingen (, , ; nds, Chöttingen) is a university city in Lower Saxony, central Germany, the capital of the eponymous district. The River Leine runs through it. At the end of 2019, the population was 118,911. General information The or ...

(1940) in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, member of the

Bulgarian Academy of Sciences The Bulgarian Academy of Sciences (abbreviated BAS; bg, Българска академия на науките, ''Balgarska akademiya na naukite'', abbreviated ''БАН'') is the National Academy of Bulgaria, established in 1869. The Academy ...

(1945) and member of the Russian

Academy of Sciences An academy of sciences is a type of learned society or academy (as special scientific institution) dedicated to sciences that may or may not be state funded. Some state funded academies are tuned into national or royal (in case of the Unite ...

(1958).

Sofia University Sofia University, "St. Kliment Ohridski" at the University of Sofia, ( bg, Софийски университет „Св. Климент Охридски“, ''Sofijski universitet „Sv. Kliment Ohridski“'') is the oldest higher education i ...

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 ant ...

and

Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first ...

in Paris, where he investigated

photoelectricity The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, and solid sta ...

for one year. Georgi Nadjakov experimentally investigated photoconducting properties of

sulphur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

. 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 electric charge or dipole polarisation. An electret generates internal and external electric fi ...

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 u ...

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, the process used by millions of photocopiers worldwide. Ca ...

some years later.

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 and ...

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

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.

External links

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

Institute of Solid State Physics

References

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