OPOMNIK: IJS KOLOKVIJ,četrtek, 29. 01. 2015; ob 13. uri; prof. dr. Jacob L. Jones

[Tanja Debevec]

Vabimo vas na 9. predavanje iz sklopa "Kolokviji na IJS" v letu 2014/15, ki bo v četrtek, 29. januarja 2015, ob 13. uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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prof. dr. Jacob L. Jones

Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, ZDA

 

 

Raziskave izvorov elektromehanične napetosti

z in situ rentgenskim in nevtronskim sipanjem

Dielektrične in piezoeletrične materiale uporabljamo za shranjevanje in pretvorbo električne in mehanične energije, zato so nepogrešljivi v vrsti naprav in aplikacij od senzorjev trka in premika, aktuatorjev, kondenzatorjev in mikroelektromehaničnih sistemov do šob za vbrizg dieselskega goriva, sonarjev in ultrazvočnih naprav. Zmogljivosti in meje delovanja teh naprav določajo dielektrične in piezoelektrične lastnosti materialov. A v večini primerov pravega odziva materiala ter s tem snovnih lastnosti ne poznamo dobro, saj je odvisen od vrste zapletenih mikrostrukturnih in kristalografskih prispevkov (npr. ionske in dipolarne polarizabilnosti, gibanja feroelastičnih domen in medfaznih mej ter lastnega piezoelektričnega pojava). V predavanju bomo predstavili naše napredne raziskave mehanike in fizike teh elektroaktivnih materialov z in situ rentgenskim in nevtronskim sipanjem, s katerimi smo določili prispevke različnih mehanizmov k snovnim koeficientom. V vseh primerih smo z mikromehanično teorijo te koeficiente kvantitativno povezali z neposrednimi meritvami prispevkov (piezoelektričnih) deformacij mreže in gibanja mej med zrni (npr. domenskih sten ali medfaznih mej).

Predavanje bo v angleščini.

Lepo vabljeni!

 

 

 




We invite you to the 9th Institute colloquium in the academic year 2014/15. The colloquium will be held on Thursday, January 29, 2015 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.

 

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prof. dr. Jacob L. Jones

Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, USA

 

 

Origins of Electromechanical Strain

Ascertained from in situ X-ray and Neutron Diffraction

 

Dielectric and piezoelectric materials are used to store and convert electrical and mechanical energy, making them essential to a broad range of applications and devices including impact and displacement sensors, actuators, capacitors, microelectromechanical systems, diesel fuel injectors, sonar, and ultrasound. In these applications, the dielectric and piezoelectric coefficients define the performance and the limits of device operation. However, the true origin of the material response, and thus the property coefficients, are not well understood because of the numerous and complex microstructural and crystallographic contributions to these properties (e.g., ionic and dipolar polarizability, ferroelastic domain wall motion, interphase boundary motion, the intrinsic piezoelectric effect, etc.). This talk will demonstrate our use of advanced in situ X-ray and neutron scattering methods to discern the underlying mechanics and physics at play in these electro-active materials, ultimately revealing the contribution of these various mechanisms to the property coefficients. In all cases, direct measurements of the contribution from lattice deformation (e.g., piezoelectric) and the motion of intragranular interfaces (e.g., domain walls, interphase boundaries) are quantitatively related to the property coefficients using micromechanics-based formulations.

 

Cordially invited!

 

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