Optimiranje priprave kalcijevog manganita

master's thesis

• Title (english): Optimization of calcium manganite synthesis
• Author: Filip Brleković
• Mentor: Jelena Macan (mentor)
• Committee member: Jelena Macan (predsjednik povjerenstva)
• Committee member: Hrvoje Ivanković (član povjerenstva)
• Committee member: Stanislav Kurajica (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-09-28, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

U ovome radu optimirana je priprava kalcijevog manganita, pri čemu je ispitano nekoliko metoda sinteze: mehanokemijska, Pechinijeva, modificirana Pechinijeva te ručna homogenizacija. Dobiveni uzorci su kalcinirani na temperaturama 400 – 1200 °C radi dobivanja kristalnog kalcijevog manganita. Sastav prašaka sintetiziranih navedenim metodama ispitan je rendgenskom difrakcijskom analizom, infracrvenom spektroskopijskom analizom, te kombiniranom diferencijalnom pretražnom kalorimetrijom i termogravimetrijskom analizom. Morfologija prašaka dobivenih Pechinijevom i metodom homogenizacije, kao najefikasnijim metodama sinteze, promatrana je pretražnom elektronskom mikroskopijom (SEM), a također je određena raspodjela veličina čestica i njihova specifična površina. Kao najefikasnija metoda odabrana je ručna homogenizacija koja daje relativno brzo, jednostavno i lagano kalcijev manganit. Stoga su iz tog praška pripravljeni uzorci za ispitivanje nanošenja tankih filmova iz suspenzija i metodom laserske ablacije (PLD). Suspenzije su pripravljene iz praška kalciniranog na 900 °C. Najpostojanije su se pokazale suspenzije u etanolu, no zbog velikih čestica nije bilo moguće dobiti homogenu prevlaku. Mete za metodu PLD dobivene su tabletiranjem iz praška kalciniranog na 900 °C te nekalciniranog prašaka. Tablete su žarene na 900 i 1200 °C te je morfologija vanjske i lomne površine ispitivana SEM-om. Tablete žarene na 900 °C nisu dovoljno sinterirane i previše su krhke, dok su one žarene na 1200 °C u potpunosti sinterirane i dovoljno kvalitetne za primjenu kao mete. Tablete dobivene iz nekalciniranih prašaka imaju krupnije kristale, ali su isto tako i poroznije zbog oslobađanja CO2 i vlage iz sirovog praška prilikom sinteriranja.

Abstract (english)

In this work the synthesis of calcium manganite was optimised through a number of different methods of synthesis: mechanochemical, manual homogenisation, Pechini and modified Pechini method. To achieve crystalline calcium manganite synthesised samples were annealed on temperatures from 400 °C to 1200 °C. Synthesised powder samples were characterised with X-ray diffraction analysis, infrared spectroscopy, differential scanning calorimetry and thermogravimteric analysis. Morphology of the powders synthesized by Pechini methods and manual homogenisation was observed by scanning electron microscope (SEM), and the particle distribution and specific surface area were determined. The manual homogenisation method was proven as the most efficient for fast, easy and simple synthesis of calcium manganite. Powder synthesised by this method was further used for drop-castings from suspensions and pulsed laser deposition (PLD) for creating thin films. Suspensions were made with powders annealed at 900 °C, ethanol suspensions were the most stable for the longest time. Particle size of powders was too great to produce fine homogeneous films. Targets for laser ablation were obtained by compaction of powders annealed at 900 °C into tablets. Tablets were annealed at 900 and 1200 °C and their surface and fracture morphology was characterized with SEM. Tablets annealed at 900 °C showed low state of sintering and high brittleness, while tablets annealed at 1200 °C had high state of sintering and were strong enough to be used as targets for PLD. Higher state of porosity was represented in tablets made from non-calcined powders due to release of CO2 and moisture during the process of sintering. These tablets also had larger crystal grains.

• Keywords: kalcijev manganit (CaMnO3); Pechinijeva metoda; ručno homogeniziranje; veličina čestica; morfologija
• Keywords (english): calcium manganite (CaMnO3); Pechini method; manual homogenisation; particle size; morphology
• Language: croatian
• URN:NBN: urn:nbn:hr:149:058241
• 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: 2020-04-28 13:05:56