{{Infobox scientist | name = Georgi S. Nadjakov | native_name = Георги Стефанов Наджаков | native_name_lang = bg | image = Георги Наджаков.jpg | image_size = | alt = | caption = | birth_date = ({{OldStyleDate|7 January|1897|26 December|1896}} | birth_place = Dupnitsa, Bulgaria | birth_name = | death_date = {{death-date and age|24 February 1981|26 December 1896}} | death_place = Sofia | resting_place = Central Sofia Cemetery | residence = | citizenship = | fields = Physics | workplaces = Sofia University; Institute of Physics, Bulgarian Academy of Sciences | alma_mater = Sofia University | doctoral_advisor = | academic_advisors = | doctoral_students = | notable_students = | known_for = | influences = | influenced = | awards = }}
'''Georgi Nadjakov''' (also spelled '''Georgi Nadzhakov or Nadjakov'''; '''Georges Nadjakoff''') ({{langx|bg|Георги Наджаков}}) ({{OldStyleDate|7 January|1897|26 December|1896}} – 24 February 1981) was a Bulgarian physicist.<ref name = "INTL WHO IS WHO 1980">{{cite book |chapter=NADJAKOV, GEORGI |title= The International Who's Who 1980-1981 |place= London |publisher= Europa Publications Limited |year = 1980 |url= https://archive.org/details/internationalwho0000unse_p7u0/page/n5/mode/2up |edition = 44TH |url-access= registration |pages=[https://archive.org/details/internationalwho0000unse_p7u0/page/898/mode/2up 898] |lang = |via= Internet Archive |accessdate= 8 February 2026}}</ref> He was a corresponding member of the Göttingen Academy of Sciences (1940) in Germany, member of the Bulgarian Academy of Sciences (1945) and member of the Russian Academy of Sciences (1958).
== Career == Sofia University sent him to specialize in the laboratories of Paul Langevin and Marie Curie in Paris, where he investigated photoelectricity for one year.<ref name = "INTL WHO IS WHO 1980"/>
Georgi Nadjakov experimentally investigated photoconducting properties of sulphur. He prepared the permanent photoelectret state of matter for the first time and published his paper in 1937<ref> {{cite journal |url=http://www1.issp.bas.bg/museum/gnadjakov/gn11-page71.html |author=Nadjakoff, Georges |title= SUR UNE NOUVELLE ESPECE DE POLARISATION PERMANENTE DES DIELECTRIQUES |year=1937|volume=204|journal=Comptes Rendus de l'Académie des Sciences de Paris |pages=1865–1866}}</ref> and 1938.<ref> {{cite journal |url=http://www1.issp.bas.bg/museum/gnadjakov/gn11-page72.html |author = Nadjakoff, G. |title= UBER EINE NEUE ART VON ELEKTRETEN: PHOTOELEKTRETEN |year=1938|volume=39|issue=6|journal=Physikalische Zeitschrift|pages=226–227 }}</ref> He called{{citation needed|date=November 2013}} the electret discovered by Mototaro Eguchi in 1919, thermoelectret and the electret discovered by him in 1937, photoelectret.<ref> {{cite web |url=https://www.youtube.com/watch?v=iqmOa3rOjTk |archive-url=https://ghostarchive.org/varchive/youtube/20211221/iqmOa3rOjTk |archive-date=2021-12-21 |url-status=live|title=Photoelectret State of Matter }}{{cbignore}}</ref><ref>{{cite book|last=Kao|first=Kwan-Chi|title=Dielectric Phenomena in Solids|chapter-url=https://books.google.com/books?id=53iDBqayjMYC&q=Eguchi+thermoelectret+Nadjakov&pg=PA283|access-date=12 November 2013|year=2004|publisher=Academic Press|isbn=978-0123965615|page=283|chapter=5: Electrets}}</ref>
Photoelectrets were the most notable achievement of Georgi Nadjakov.<ref name = "INTL WHO IS WHO 1980"/> Its practical application led to the invention of the photocopier by Chester Carlson some years later.
Since 1958 Nadjakov had been a member of the Pugwash Movement of Scientists for Peace.<ref>{{cite book |author= Rotblat, Joseph |author-link= Joseph Rotblat |title= The Pugwash - The First Ten Years: History of the Conferences on Sciences and World Affairs |place= London |publisher= Heinemann |year= 1967 |url=https://archive.org/details/pugwashfirstteny0000jrot/page/n3/mode/2up |url-access= registration |page=[https://archive.org/details/pugwashfirstteny0000jrot/page/94/mode/2up?view=theater 95] |via= Internet Archive}}</ref>
==Honours== *Nadjakov Glacier on Graham Land in Antarctica 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.<ref>{{Cite web|url=http://www1.issp.bas.bg/museum/m11-eps-hs.html|title = Georgi Nadjakov Study – EPS Historic Site}}</ref>
==References== {{Reflist}}
==External links== * [http://www1.issp.bas.bg/museum/gnadjakov/gn11-page2.html Academician George Stefanov Nadjakov], on the site of the Institute of Solid State Physics at the Bulgarian Academy of Sciences * [http://www.issp.bas.bg Institute of Solid State Physics]
== External links == * {{cite book |author= Rotblat, Joseph |author-link = Joseph Rotblat |title= Scientists in the Quest for Peace: A History of the Pugwash Movement |year= 1972|publisher= MIT Press |place= Cambridge, MA and London |url= https://archive.org/details/scientistsinques0000rotb/page/n5/mode/2up?view=theater |url-access = registration |pages= 91, 156, 167, 183, 186, 196, 211, 219, 296, 316, 327, 357, 373}} * {{cite web |title= Founding Fathers: Georgi Nadjakov |date= 8 January 2023 |publisher= Joint Institute for Nuclear Research |accessdate= 16 September 2023 |url = http://www.jinr.ru/posts/founding-fathers-georgi-nadjakov/}}
{{Authority control}}
{{DEFAULTSORT:Nadjakov, Georgi}} Category:1896 births Category:1981 deaths Category:Members of the Bulgarian Academy of Sciences Category:20th-century Bulgarian physicists Category:People from Dupnitsa Category:Rectors of Sofia University Category:Burials at Central Sofia Cemetery