Fazni razvoj u sustavu ZrO2-CaO

master's thesis

• Title (english): Phase development in system ZrO2-CaO
• Author: Valentina Borko
• Mentor: Goran Štefanić (mentor)
• Committee member: Željka Soldin (predsjednik povjerenstva)
• Committee member: Tajana Preočanin (član povjerenstva)
• Committee member: Sanda Rončević (član povjerenstva)
• Committee member: Biserka Prugovečki (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2018-02-05, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Čvrste otopine sustava ZrO2−CaO sintetizirane su primjenom dviju različitih sintetskih
metoda: koprecipitacijom polaznih vodenih otopina, te kugličnim mljevenjem polaznih
nitratnih soli. Dobiveni prekursori analizirani su pomoću DSC analize i kalcinirani na zraku
na temperaturama do 1000 °C te analizirani na sobnoj temperaturi pomoću Ramanove
spektroskopije, PXRD, FE−SEM i EDS analize. Fazni razvoj u sustavu ZrO2-CaO ovisi o
korištenoj metodi sinteze prekursora. Precizno su određeni parametri jedinične ćelije ZrO2
tipa čvrstih otopina pomoću Rietveldovog utočnjavanja. Maksimalna topljivost Ca2+ iona (~
45 % množinskog udjela) pojavila se u amorfnim prekursorima ZrO2 faze. Žarenje na 1000
°C smanjuje topljivost Ca2+ iona na ~ 24 %. Porastom udjela Ca2+ u čvrstim otopinama
značajno se smanjuje vrijednost parametra c tetragonskog polimorfa te je određena granica
prijelaza iz metastabilne tetragonske u stabiliziranu kubičnu formu kod ~ 14 % množinskog
udjela kalcija.

Abstract (english)

Solid solutions of the system ZrO2−CaO were synthesised using two synthetic routes:
co−precipitation from aqueous solutions and ball milling of the corresponding nitrate salts.
The obtained precursors were analysed using DSC and calcined in air at temperatures up to
1000 °C. Calcined samples were analysed at RT using PXRD, Raman spectroscopy, FE−SEM
and EDS. The phase development of ZrO2-CaO system depend on the synthetic route used to
obtain starting precursors. Precise unit-cell parameters of the ZrO2-type solid solutions were
determined by using Rietveld refinements of the powder diffraction patterns. Maximum
solubility of Ca2+ ions (~ 45 mol%) occured in the amorphous precursors to the ZrO2−type
phase. Thermal treatment at 1000 °C decreased the solid solubility of Ca2+ ions to ~ 24 mol%.
By increasing Ca2+ content the lattice parameter c in tetragonal polymorph of zirconia
decreases rapidly and tetragonal to cubic phase boundary in stabilized ZrO2 was located
around 14 mol% Ca.

• Keywords: čvrste otopine; elektronska mikroskopija; fazna analiza; granice topljivosti; Ramanova spektroskopija; rendgenska difrakcija na prahu; ZrO2−CaO
• Keywords (english): electron microscopy; phase analysis; PXRD; Raman spectroscopy; solid solutions; solubility limits; ZrO2−CaO
• Language: croatian
• URN:NBN: urn:nbn:hr:217:507230
• Study programme: Title: Graduate university studies in chemistry; specializations in: Research programme; Course: Research programme; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra kemije (magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2020-02-05
• Created on: 2018-02-22 11:01:17