Utjecaj miješanih oksida prijelaznih metala na polaronsku vodljivost vanadatno-fosfatnih stakala

doctoral thesis

• Title (english): Influence of mixed transition metal oxides on the polaronic conductivity of vanadate-phosphate glasses
• Author: Marta Razum
• Mentor: Ana Šantić (mentor)
• Committee member: Višnja Vrdoljak (predsjednik povjerenstva)
• Committee member: Marijana Jurić (član povjerenstva)
• Committee member: Jasminka Kontrec (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2024-10-07, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

U ovoj doktorskoj disertaciji istražena su strukturna i električna svojstva binarnih vanadatno-fosfatnih stakala, te ternarnih fosfatnih stakala u kojima je V2O5 zamijenjen s oksidima prijelaznih metala: WO3, MoO3 i Fe2O3. Struktura stakala istražena je Ramanovom spektroskopijom, a električna svojstva istražena su impedancijskom spektroskopijom. Istraživanje binarnog sustava pokazalo je da polaronska vodljivost u ovim staklima snažno ovisi o strukturi te je linearno povećanje vodljivosti s porastom udjela V2O5 posljedica ugradnje različitih vanadatnih poliedara koji se međusobno raznoliko povezuju u fosfatnoj mreži tvoreći višestruke pogodne puteve vodljivosti što povećava vjerojatnost polaronskih skokova. U ternarnim staklima zamjena V2O5 s WO3/MoO3 smanjuje polaronsku vodljivost, pri čemu se prijenos naboja odvija putem vanadatnih strukturnih jedinica. Kod stakala s Fe2O3, vodljivost pokazuje duboki minimum pri 27 % množinskog udjela Fe2O3 što se pripisuje prijelazu mehanizma iz transporta kroz dominantno vanadatnu strukturu u transport kroz strukturu s miješanim željeznim i vanadatnim jedinicama u kojoj ioni željeza doprinose polaronskom transportu.

Abstract (english)

In this doctoral dissertation, the structural and electrical properties of binary vanadate-phosphate glasses, as well as ternary phosphate glasses where V2O5 is replaced with transition metal oxides, WO3, MoO3, and Fe2O3, were investigated. The glass structure was examined using Raman spectroscopy, while electrical properties were studied by impedance mspectroscopy. Research on the binary system revealed that polaronic conductivity in these glasses strongly depends on structure, with a linear increase in conductivity with increasing V2O5 content being a consequence of incorporating different vanadate polyhedra that are interconnected in the phosphate network, forming multiple favourable conductivity paths that increase the likelihood of polaronic jumps. In ternary glasses, replacing V2O5 with WO3/MoO3 reduces polaronic conductivity, with charge transfer occurring through vanadate structural units. In Fe2O3 glasses, conductivity exhibits a deep minimum at 27% Fe2O3 molar fraction, attributed to a transition from transport through a predominantly vanadate structure to transport through a mixed iron-vanadate structure where iron ions contribute to polaronic transport.

• Keywords: električna svojstva; impedancijska spektroskopija; polaronska vodljivost; struktura; vanadatno-fosfatna stakla
• Keywords (english): electric properties; impedance spectroscopy; polaronic conductivity; structure; vanadate-phosphate glasses
• Language: croatian
• URN:NBN: urn:nbn:hr:217:268746
• Promotion: 2024
• Study programme: Title: Doctoral study in chemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 139, XXIV str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-07-17 12:08:45