The Effect of Increasing Iron Concentration on Structural and Magnetic Properties of the Swedenborgite Material CaBaCo(2-x)Fe(2+x)O7

Halouzka, Tobias (2021) The Effect of Increasing Iron Concentration on Structural and Magnetic Properties of the Swedenborgite Material CaBaCo(2-x)Fe(2+x)O7. Master's Thesis / Essay, Chemistry.

Preview	Text mCHEM_2021_HalouzkaT.pdf Download (3MB) | Preview
	Text toestemming.pdf Restricted to Registered users only Download (118kB)

Abstract

This project involved the synthesis of swedenborgite material CaBaCo(2-x)Fe(2+x)O7 (x = 0-1, in increments of 0.1 atomic units) using a sol-gel auto combustion method. The compounds were synthesized in a pellet form to improve sample crystallinity. PXRD measurements show that the best synthetic conditions from those that were tested in this project are sintering at 1120°C for 24 hours. All samples were contaminated due to a vaporization of cobalt oxide, which required polishing of the sintered pellets. Unpolished samples showed the presence of an unidentified surface phase, similar to a cobalt-iron based spinel structure. Measurements of magnetization vs. temperature showed antiferromagnetic ordering of CaBaCo2Fe2O7 at 161 K and a spin-flop transition at 41 K. For CaBaCo1.9Fe2.1O7, only the first of these transitions is visible, at 154 K. The rest of the studied composition showed a spin crossover transition over a range of 100-200 K. The largest magnetization was seen in samples with a higher amount of cobalt. M-H measurements showed largely antiferromagnetic behvaiour, as well as some ferromagnetic behaviour originating in the spin canting of the antiferromagnet. The compositions of each polished sample were measured using EDS, and showed substantial phase separation as a result of the increased sintering temperatures.

Item Type:	Thesis (Master's Thesis / Essay)
Supervisor name:	Blake, G.R.
Degree programme:	Chemistry
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	11 Jun 2021 11:27
Last Modified:	11 Jun 2021 11:27
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/24534

Actions (login required)

View Item