Određivanje udjela amorfne faze u manganitima

master's thesis

• Title (english): Determination of amorphous phase content in manganites
• Author: Valentina Jakopović
• Mentor: Jelena Macan (mentor)
• Committee member: Jelena Macan (predsjednik povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Committee member: Krunoslav Žižek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-07-10, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Kristale karakterizira uređena kristalna struktura, dok amorfne tvari nemaju uređenu strukturu. Razlika između amorfnih i kristalnih tvari je u stupnju prostorne uređenosti, ali i u brojim fizikalnim svojstvima. Amorfna faza utječe na fizikalna svojstva mnogih materijala poput funkcionalne keramike (perovskiti), farmaceutika, građevinskih materijala itd. Kod perovskita, prisutnost amorfne faze utječe na katalitička svojstva. Cilj ovog rada bio je razviti pouzdanu tehniku za kvantificiranje amorfne faze u uzorcima lantanovog (LaMnO3), kalcijevog (CaMnO3) i barijevog (BaMnO3) manganita. Korišteni uzorci manganita pripremljeni su limunskim i koprecipitacijskim postupkom u prethodnim istraživanjima, a u svrhu određivanja udjela amorfne faze u njih je umiješano 10 % Al2O3 (korunda) kao standarda. Snimljeni su difraktogrami pripremljenih uzoraka te je proveden postupak Rietveldove metode utočnjavanja u besplatnom softverskom paketu FullProf. Isti postupak je zatim primijenjen za određivanje porasta udjela amorfne faze u La0,8Sr0,2MnO3 uzorku pripremljenom koprecipitacijskim postupkom i podvrgnutom naknadnom usitnjavanju u planetarnom mlinu. Na temelju dobivenih rezultata utvrđeno je da ovakva tehnika za kvantificiranje udjela amorfne faze pouzdana i jednostavna.

Abstract (english)

Crystals are characterized by an ordered crystalline structure, while amorphous substances do not have an ordered structure. The difference between amorphous and crystalline substances is in the degree of spatial arrangement, but also in numerous physical properties. The amorphous phase affects the physical properties of many materials such as functional ceramics (perovskites), pharmaceuticals, construction materials, etc. In perovskites, the presence of the amorphous phase affects catalytic properties. The aim of this work was to develop a reliable technique for quantifying the amorphous phase content in samples of lanthanum (LaMnO3), calcium (CaMnO3) and barium (BaMnO3) manganites. The used manganites samples were prepared in previous studies, and to determine the amorphous phase content 10 % of Al2O3 (corundum) as standard was mixed with manganites. The diffractograms of prepared samples were recorded and Rietveld refinement was done using the open-source FullProf software. The same procedure was then applied for the determination of amorphous phase content increase in La0.8Sr0.2MnO3 sample prepared by coprecipitation and then ground by ball milling. Based on the obtained results, this technique for quantifying the amorphous phase was found to be reliable and simple.

• Keywords: amorfna faza; manganiti; rendgenska difrakcijska analiza; Rietveldova metoda utočnjavanja
• Keywords (english): amorphous phase; manganites; X-ray diffraction analysis; Rietveld refinement
• Language: croatian
• URN:NBN: urn:nbn:hr:149:431299
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-07-26 14:49:29