Hidrotermalna sinteza manganita

master's thesis

• Title (english): Hydrothermal synthesis of manganites
• Author: Ivana Bandić
• Mentor: Jelena Macan (mentor)
• Committee member: Jelena Macan (predsjednik povjerenstva)
• Committee member: Marica Ivanković (član povjerenstva)
• Committee member: Anamarija Rogina (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Moderno društvo orijentirano je prema razvoju novih, visokoučinkovitih tehnologija kojima bi se umanjili negativni utjecaji fosilnih goriva na ekologiju i ekonomiju te omogućio daljnji održivi razvoj. Perovskiti, materijali koji od 50-ih godina 20. stoljeća sve više privlače pozornost znanstvenika zbog specifičnih svojstava, još uvijek se ne upotrebljavaju na komercijalnoj razini. Potencijal njihove praktične uporabe leži u izvrsnim električnim, magnetskim i katalitičkim svojstvima. Cilj ovoga rada bio je istražiti mogu li se nanočestice lantanova manganita sintetizirati hidrotermalnom metodom i odrediti optimalne uvjete njihove sinteze. Pripravljeni uzorci analizirani su pomoću termogravimetrijske (TGA) i rendgenske difrakcijske analize (XRD), infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i pretražne elektronske mikroskopije (SEM). Rezultati hidrotermalne sinteze uspoređeni su s rezultatima koprecipitacijske sinteze i mikrovalno potpomognute hidrotermalne sinteze. Utvrđeno je da u sva tri slučaja lantanov manganit nije nastao direktno nakon sinteze, već je dobivene prekursore bilo potrebno žariti. Ni u tom slučaju ne nastaje čisti lantanov manganit, već nastaju i lantanovi i manganovi oksidi. Lantanov oksid može se ukloniti otapanjem da bi se dobio čisti LaMnO3. Nastali LaMnO3 ima veličinu kristalita u rasponu 16 – 54 nm, što je i dvostruko manje nego kod limunskog postupka.

Abstract (english)

Modern society is orientated towards the development of novel, highly-efficient technologies to reduce the negative impact of fossil fuels on the ecology and economy and to provide further sustainable development. Perovskites, materials that have increasingly attracted the attention of scientists since the 1950s due to their specific properties, are still not used on a commercial level. The great potential for their practical use lies in their exceptional electrical, magnetic and catalytic properties. The aim of this work is to investigate whether lanthanum manganite nanoparticles can be synthesized by hydrothermal method and to determine the optimal synthesis conditions. Prepared samples were analysed by thermogravimetric (TGA) and X-ray diffraction analysis (XRD), infrared spectroscopy with Fourier transformation (FTIR) and scanning electron microscopy (SEM). The results of hydrothermal synthesis were compared with the results obtained by coprecipitation synthesis and microwave-assisted hydrothermal synthesis. It is established that in all three cases lanthanum manganite was not formed directly after synthesis, but the obtained precursors had to be annealed. Pure lanthanum manganite was not formed even after annealing, since lanthanum and manganese oxides were also formed. The lanthanum oxide can be removed by dissolution to give pure LaMnO3. The resulting LaMnO3 has a crystallite size in the range 16 – 54 nm, which is twice as small as in the citrate process.

• Keywords: hidrotermalna sinteza; manganiti; nanomaterijali; perovskiti
• Keywords (english): hydrothermal synthesis; manganites; nanomaterials; perovskites
• Language: croatian
• URN:NBN: urn:nbn:hr:149:789531
• Study programme: Title: Materials Science and Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-11-21 14:44:26