Tragovi brzih teških iona u SrTiO3

doctoral thesis

• Title (english): Swift heavy ion tracks in SiTiO3
• Author: Marko Karlušić
• Mentor: Milko Jakšić (mentor)
• Committee member: Damir Bosnar (predsjednik povjerenstva)
• Committee member: Milko Jakšić (član povjerenstva)
• Committee member: Hrvoje Buljan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2012-01-10, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics
• Universal decimal classification (UDC): 53 - Physics

Abstract

Međudjelovanje energetskog teškog iona s materijom može rezultirati dramatičnim promjenama materijala, što čini ozračavanja pojedinačnim ionima jedinstvenim oruđem za modifikacije na nanoskali. Potrebne ekstremne gustoće energije mogu biti postignute koristeći samo brze teške ione (swift heavy ions, SHI) ili ione visokog nabojnog stanja (highly charged ions, HCI). Trajno oštećenje materijala uslijed ozračavanja s ovako teškim i energetskim ionom naziva se ionski trag, kojeg je moguće opažati različitim eksperimentalnim metodama poput u ovom radu korištenih mikroskopije atomskih sila (atomic force microscopy, AFM) ili Rutherfordovog raspršenja u stražnje kuteve u kanalirajućoj geometriji (Rutherford Backscattering Spectroscopy in channeling geometry, RBS/c). U ovom radu, istraživane su promjene u stroncij titanatu (SrTiO3) nastale ozračavanjem brzim teškim ionima. Uzorci su ozračavani snopovima iona joda MeVskih energija koristeći 6 MV EN Tandem Van de Graaff ubrzivač na Institutu Ruđer Boškovič. Promjene na površini materijala istraživane su koristeći AFM na Sveučilištu u Duisburgu te na Institutu Ruđer Bošković, dok su promjene unutar materijala istraživane pomoću RBS/c na Helmholtz Zentrum Dresden-Rossendorf. Glavni rezultat ovog istraživanja je određivanje energijskog praga brzih teških iona za formiranje površinskih i dubinskih tragova u SrTiO3. Eksperimentalna novost prikazana u ovom radu je otkriće ovisnosti praga za formiranje ionskog traga o kutu ozračavanja brzim teškim ionima u odnosu na kristalografske osi. Iako je grupa u Duisburgu dala teorijsko objašnjenje za ionske tragove koristeći neelastični model termalnog vala (inelastic thermal spike model, ITSM), u ovoj doktorskoj disertaciji opisano je i novo razvijeno proširenje analitičkog modela termalnog vala (analytical thermal spike model, ATSM) pomoću kojeg je dan opis tragova brzih teških iona u SrTiO3. Posebno je značajno da je razvijeno proširenje modela prikladno i za opis tragova iona visokog nabojnog stanja iz rezultata drugih autora dostupnih u literaturi.

Abstract (english)

The interaction of an energetic heavy ion with solid matter can result in dramatic changes of the target material, which makes single ion irradiation a unique tool for materials modification on the nanoscale. The required extreme energy density can be achieved only by two principal categories of heavy ions: swift heavy ions (SHI) and highly charged ions (HCI). Permanent damage of the material caused by such heavy and energetic ion is called an ion track. It can be observed, among others, using methods like atomic force microscopy (AFM), or Rutherford Backscattering Spectroscopy in channeling geometry (RBS/c) that are used here. In this work, changes in swift heavy ion irradiated strontium titanate (SrTiO3) samples were investigated. Samples were irradiated with iodine ions in the MeV energy range using 6 MV EN Tandem Van de Graaff accelerator at the Ruđer Bošković Institute. Changes on the sample surface were investigated using AFM at University in Duisburg and at Ruđer Bošković Institute, while changes within the material were investigated using RBS/c at Helmholtz Zentrum Dresden-Rossendorf. The main result of this work is determination of swift heavy ion energy threshold for ion track formation in SrTiO3, both on the surface and in the bulk of the sample. Experimental novelty presented in this work is discovery of ion track formation threshold dependence on angle of ion irradiation with respect to the crystallographic axes. Although Duisburg group provided theoretical explanation for ion track formation using inelastic thermal spike model (ITSM), an extension of analytical thermal spike model (ATSM) developed in this thesis was used to describe experimental data presented within this work. This extension was also found suitable to describe highly charged ion track data available in the literature.

• Keywords: brzi teški ion; ionski trag; prag za formiranje ionskog traga; SrTiO3; AFM; RBS/c; model termalnog vala; ion visokog nabojnog stanja
• Keywords (english): swift heavy ion; ion track; ion track formation threshold; SrTiO3; AFM; RBS/c; thermal spike model; highly charged ion
• Language: croatian
• URN:NBN: urn:nbn:hr:217:129362
• Study programme: Title: Physics; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
• Type of resource: Text
• Extent: 125 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-08-23 10:13:53