Priprava in karakterizacija aluminij-kalcijevega titanata(IV)

Dežan, Jan (author), Golobič, Amalija (mentor)

V diplomskem delu sem se osredotočil na pripravo keramične spojine aluminij-kalcijev titanat(IV) (okrajšano CTA). Sledila je še strukturna karakterizacija, saj po sklepih preteklih del elementna sestava ni bila jasno opredeljena, struktura pa še ne določena. V okviru priprave CTA sem se omejil na sintezo v obliki žganja dobro zmletih reaktantov do produkta (sintranje) ter na tvorbo trdnih reaktantov iz raztopine preko precipitacije (t.i. mokra kemijska sinteza), ki sem jih nato tudi sintral do produkta. Da bi zagotovil tem boljšo pretvorbo reaktantov v produkt sem sledil stehiometriji reakcije na dve predvideni elementni sestavi CTA in sicer CaTi3Al8O19 ter Ca3Ti8Al12O37. V okviru karakterizacije CTA smo uporabili dve metodi in sicer rentgensko praškovno difrakcijo (XRPD) ter površinsko analizo s pomočjo vrstičnega elektronskega mikroskopa (SEM). S pomočjo računalniškega programa CSM sem izvedel kvalitativno fazno analizo. S programom Topas pa sem z Rietveldovo metodo prilagajanja izračunanega difraktograma izmerjenemu naredil kvantitativno fazno analizo in na izbranem vzorcu tudi strukturno določitev CTA. To strukturo sem prikazal s programom ATOMS. S pomočjo SEM mikroskopije in EDS analize sem določil elementno sestavo faz v izbranih vzorcih. Tako EDS analiza faze CTA kot njena strukturna določitev potrjujeta CTA s formulo CaTi3Al8O19. Med izvajanjem analiz sem pogosto opazil prisotnost neznane faze, ki mi je ni uspelo identificirati, je pa njen difraktogram zelo podoben difraktogramom spojin tipa CaTi(3-x)ZrxO7. Ali je cirkonij pri ponovnih sintranjih na nek način res vstopil v sistem, ali pa gre za še nepoznano snov s podobno zgradbo, bo stvar prihodnjih preučevanj.

• Language: Slovenian
• Keywords: aluminij-kalcijev titanat(IV), sintranje, mokra kemijska sinteza, rentgenska praškovna difrakcija, vrstična elektronska mikroskopija, Rietveldova metoda.
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-119698
• COBISS.SI-ID: 30855171
• Publication date in RUL: 10.09.2020

Secondary language

• Language: English
• Title: Preparation and characterization of aluminium calcium titanate(IV)

Abstract

In this thesis I focused on the preparation of the ceramic compound aluminium-calcium titanate(IV) (abrev. CTA) and on the subsequent structural characterization, since past studies could not clearly conclude its composition. Its structure has also not yet been determined. Regarding the preparation of CTA, I limited myself to a synthesis in the form of burning well ground reactants (sintering) as well as forming a solid mixture of reactants from a liquid solution using precipitation (so-called wet chemical synthesis) and subsequently sintering it. To ensure better conversion I followed the reaction stoichiometry of two possible element compositions of CTA, these being CaTi3Al8O19 and Ca3Ti8Al12O37. For the characterization of CTA, we used X-ray powder diffraction (XRPD) and surface analysis with a scanning electron microscope (SEM). I performed qualitative phase analysis by program CSM. For the quantitative phase analysis and structure determination of CTA I used Topas program. ATOMS program was used for the presentation of structure of CTA. With the help of SEM microscopy with EDS analysis I determined the elemental composition of phases in the selected samples. Both, the results of EDS analysis of CTA and its structure determination confirm the formula CaTi3Al8O19. During the analyses I often noticed the presence of an unknown phase, which I didn't manage to identify. Its diffraction pattern was very similar to those of CaTi(3-x)ZrxO7 compounds. Whether zirconium in some way really entered in the system during repeated sintering, or whether it is an as yet unknown substance with a similar structure, will be a matter of future studies.

• Keywords: aluminium-calcium titanate(IV), sintering, wet chemical synthesis, x-ray powder diffraction, scanning electron microscopy, Rietveld refinement method.