Priprava finih prašaka La1-xSrxMnO3 mljevenjem

undergraduate thesis

• Title (english): Preparation of fine La1-xSrxMnO3 powders by milling
• Author: Lucija Vuković
• 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: 2022-09-22, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Cilj rada bio je pripremiti fine praške La1-xSrxMnO3 mljevenjem. La1-xSrxMnO3 dobiven je postupkom koprecipitacije, u kojem se dodaje precipitacijski reagens NH4HCO3 koji smanjuje topljivost i nastaje talog. Dobiveni talog žaren je pri 1200 °C pri čemu dolazi do gubitka karbonata iz uzorka i kristalizacije La1-xSrxMnO3. Struktura i sastav dobivenih prašaka karakterizirani su metodom rendgenske analize (XRD) kojom je dokazan sastav manganitne faze u žarenim uzorcima i karbonatne faze u prekursoru. Infracrvenom spektroskopijom (FTIR) potvrđene su karbonatne vrpce u prekursoru, prisutnost željene ionske veze u žarenom uzorku, i dokazano je postojanje Mn-O-Mn veze u mljevenim žarenim uzorcima. Žareni uzorci dalje su mljeveni u mlinu u različitim vremenskim intervalima od jednog, dva i tri sata da bi se ispitao utjecaj duljine mljevenja na svojstva nastalih prašaka. Dodatno je provedeno mokro mljevenje u etanolu u trajanju od dva sata. Iz finih prašaka dobivenih mljevenjem pripremljene su zatim tanke prevlake. Prašci su prethodno homogenizirani u ahatnom tarioniku s otopinom poli-vinilidenfluorida u 1-metil-2-pirolidinonu kako bi se dobila homogena pasta, a zatim su na predmetnim stakalcima izvučene prevlake debljine 20 μm doctor blade tehnikom. Morfologija dobivenih prevlaka istražena je pretražnim elektronskim mikroskopom (SEM). Dobivene keramičke prevlake slabo prianjaju uz podlogu i skidaju se dodirom. Stoga ovaj pristup nije pogodan za dobivanje tankih keramičkih prevlaka
La1-xSrxMnO3.

Abstract (english)

The aim of the work was to prepare fine La1-xSrxMnO3 powders by milling. La1-xSrxMnO3 was obtained by the coprecipitation process, in which the precipitation reagent NH4HCO3 was added to reduce the solubility and form a precipitate. The precipitate obtained was annealed at 1200 °C, during which the carbonate from the sample is lost and La1-xSrxMnO3 crystallizes. The structure and composition of the obtained powders were characterized by the X-ray analysis (XRD), which proved the composition of the manganite phase in the annealed samples and the carbonate phase in the precursor. Infrared spectroscopy (FTIR) confirmed the carbonate bands in the precursor, the presence of the desired ionic bond in the annealed sample and proved the existence of the Mn-O-Mn bond in milled annealed samples. The annealed samples were further milled at different time intervals, one, two and three hours, in order to examine the influence of the length of milling on the properties of the resulting powders. In addition, wet milling in ethanol was carried out for two hours. Thin coatings were then prepared from the fine powders obtained by milling. The powders were previously homogenized in an agate mortar with a solution of polyvinylidene fluoride in 1-methyl-2-pyrrolidinone to obtain a homogeneous paste, and then 20 μm thick coatings were drawn on the glass slides using the doctor blade technique. The morphology of the obtained coatings was investigated with a scanning electron microscope (SEM). The resulting ceramic coatings adhere poorly to the substrate and come off by touching. Therefore, this approach is not suitable for obtaining thin La1-xSrxMnO3 ceramic coatings.

• Keywords: koprecipitacija; mljevenje; prevlake; stroncijem dopiran lantanov manganit
• Keywords (english): coprecipitation; milling; coatings; strontium-doped lanthanum manganite
• Language: croatian
• URN:NBN: urn:nbn:hr:149:721204
• Project: Number: IP-2018-01-5246; Title: Nanokompoziti s perovskitima za fotovoltaike, fotokatalizu i senzoriku; Acronym: NanoPeroPhotoSens; Leader: Andreja Gajović; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Chemical Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-03-15 09:43:44