IJS KOLOKVIJ, sreda, 3. 6. 2020, ob 13.00 uri, prof. dr. Darja Lisjak

[Natasa.Gosevac at ijs.si]

Vabimo vas na 12. predavanje iz sklopa "Kolokviji na IJS" v letu 2019/20, ki bo v sredo, 3. junija 2020, ob 13. uri zopet v Veliki predavalnici Instituta »Jožef Stefan« na Jamovi cesti 39 v Ljubljani. Predavanje lahko spremljate tudi na youtubu na spletnem naslovu  <https://www.youtube.com/watch?v=_MLT_8FnB_s&feature=youtu.be> https://www.youtube.com/watch?v=_MLT_8FnB_s&feature=youtu.be

Napovednik predavanja najdete tudi na naslovu  <http://www.ijs.si/ijsw/Koledar_prireditev> http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na  <http://videolectures.net/kolokviji_ijs> http://videolectures.net/kolokviji_ijs. 

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prof. dr. Darja Lisjak

Institut Jožef Stefan, Ljubljana 

 

Heksaferiti: raznovrstni in edinstveni magnetni materiali 

 

Heksaferiti so posebna vrsta magnetnih materialov in osnovni gradniki, nedavno odkritih, feromagnetnih tekočin. Najdemo jih v faznem diagramu MOFe2O3MeO (M = dvovalentna kovina z velikim ionskim radijem, Me = dvovalentna prehodna kovina). Heksaferiti različnih kemijskih sestav kristalizirajo v številnih strukturnih politipih. Vsi heksaferitni politipi rastejo v obliki heksagonalnih ploščic in imajo enoosno magneto-kristalno anizotropijo, zaradi česar so primerni za trajne magnete, magnetno zapisovanje, mikrovalovne magnetne naprave in asborberje. Heksaferiti tipa M imajo najbolj enostavno strukturo in so tudi najbolje raziskani, kar še posebej velja za Ba heksaferit s kemijsko sestavo BaFe12O19. Lahka os magnetizacije Ba heksaferita je pravokotna na osnovno ravnino ploščice, kar je značilno samo za nekatere politipe heksaferitov in edinstveno med magnetnimi materiali. Zaradi te posebne lastnosti lahko posamezne nanoploščice Ba heksaferita vodimo z zelo šibkim zunanjim magnetnim poljem, primerljivim z Zemljinim. S prilagajanjem interakcij med nanoploščicami Ba heksaferita smo odkrili veliko zanimivih lastnosti le-teh ter celo nove materiale, kot npr. feromagnetne suspenzije in tekoče magnete. Povzeli bomo dve desetletji raziskav na Institutu Jožef Stefan, ki so vodile do teh odkritij.

 

Predavanje bo v angleščini.

Lepo vabljeni!

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We invite you to the 12th Institute colloquium in the academic year 2019/20. The colloquium will be held on Wednesday June 3, 2020 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. The colloquium will also be aired live on youtube at  <https://www.youtube.com/watch?v=_MLT_8FnB_s&feature=youtu.be> https://www.youtube.com/watch?v=_MLT_8FnB_s&feature=youtu.be

To read the abstract click   <http://www.ijs.si/ijsw/Koledar_prireditev> http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on   <http://videolectures.net/kolokviji_ijs> http://videolectures.net/kolokviji_ijs.

 

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prof. dr. Darja Lisjak

Jožef Stefan Institute, Ljubljana, Slovenia

 

Hexaferrites: Versatile and unique magnetic materials

 

Hexaferrites are a special class of magnetic materials that constitute recently discovered ferromagnetic liquids.  They are found in the ternary phase diagram MO-Fe2O3-MeO, where M is a large bivalent metal and Me is a bivalent transition metal. Hexaferrites with different chemical compositions crystallize in numerous structural polytypes. All polytypes grow as thin hexagonal platelets with uniaxial magneto-crystalline anisotropy, which makes them suitable for permanent magnets, magnetic recording, microwave magnetic devices and absorbers. Structurally the simplest and the most studied hexaferrites are of M-type, in particular Ba hexaferrite with the chemical composition of BaFe12O19. Its magnetic easy axis is perpendicular to the basal plane of a platelet, which is unique only to some hexaferrite polytypes among all known magnetic materials. As a consequence, individual Ba hexaferrite nanoplatelets can be manipulated by a weak external magnetic field comparable to the Earth's magnetic field. By tuning the interactions between the Ba hexaferrite nanoplatelets, many interesting behaviours and even new materials like ferromagnetic suspensions and liquid magnets were discovered. We will summarize two decades of the research at the Jožef Stefan Institute that led to those discoveries.

 

Cordially invited!

 

 

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