Georgi Nadjakov

{{Infobox scientist

| name = Georgi S. Nadjakov

| native_name = Георги Стефанов Наджаков

| native_name_lang = bg

| image = Георги Наджаков.jpg

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| birth_date = 26 December 1896

| birth_place = Dupnitsa, Bulgaria

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| death_date = {{death-date and age|24 February 1981|26 December 1896}}

| death_place = Sofia

| resting_place = Central Sofia Cemetery

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| nationality = Bulgarian

| fields = Physics

| workplaces = Sofia University; Institute of Physics, Bulgarian Academy of Sciences

| alma_mater = Sofia University

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}}

Georgi Nadjakov (also spelled Georgi Nadzhakov or Nadjakov; Georges Nadjakoff) ({{langx|bg|Георги Наджаков}}) (26 December 1896 – 24 February 1981) was a Bulgarian physicist. 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).

Sofia University sent him to specialize in the laboratories of Paul Langevin and Marie Curie in Paris, where he investigated photoelectricity for one year.

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

{{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}} and 1938.

{{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

}} 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.

{{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}}{{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}}

Photoelectrets were the most notable achievement of Georgi Nadjakov. 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.{{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}}