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A Raman- and XRD study of the crystal chemistry of cobalt blue
Dissertation (MSc)--University of Pretoria, 2009.
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| Format: | Thesis |
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University of Pretoria
2013
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| _version_ | 1867613504522944512 |
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| access_status_str | Open Access |
| author2 | Van Rooyen, Petrus H. |
| author_browse | Van Rooyen, Petrus H. |
| author_facet | Van Rooyen, Petrus H. |
| collection | Thesis |
| dc_rights_str_mv | © 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2009. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/29925 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:12.164Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/29925 A Raman- and XRD study of the crystal chemistry of cobalt blue Van Rooyen, Petrus H. Paul, S.O. ellenmusili20@aol.co.uk Mwenesongole, Ellen Musili Raman spectroscopy Cobalt aluminate spinels Crystal chemistry of cobalt blue Xrd X-ray powder diffraction UCTD Dissertation (MSc)--University of Pretoria, 2009. The aim of this research project was to synthesise both the normal and inverse cobalt aluminate spinels by various methods and characterise them mainly by Raman spectroscopy with the support of X-ray powder diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), energy disperse spectroscopy (EDS), and scanning electron microscopy (SEM). Four different synthesis methods (glycine-gel, citrate-gel, polyol and solid-state) were used to synthesise the cobalt aluminate powders with the general formula CoIICoIIIxAl2-xO4 (where x = 0-2). The gel or powder precursors were annealed at various temperatures ranging from 350ºC - 1000ºC. The properties of the intermediate and final products, influenced by the synthesis method, processing temperature, processing time and particle size, were compared. Raman spectra and XRD patterns indicating the presence of both normal and inverse cobalt aluminate spinel were observed. The inverse spinel was identified both as a transitional phase as well as a final phase, depending on the synthesis method and annealing temperature used. The various synthesis methods were also used to gain further insight into the crystal chemistry of cobalt aluminate. The solid-state method is the more traditional synthesis method. Solution techniques (glycine-gel, citrate-gel and polyol) were used in an attempt to synthesise blue cobalt aluminate at relatively low temperatures and processing times in order to obtain homogeneous, nanosized crystals with broad applicability. The polyol method was found to be most favourable for the synthesis of blue cobalt aluminate with regard to processing temperature and processing time. The various characterisation methods used, show that the intensity of the colour of the powders produced are strongly related to the degree of material crystallinity as well as Al/Co ratio. Inverse (Co2AlO4) and Co3O4 spinels are formed at lower temperatures or when the Co/Al ratio is greater than 0.5. The normal spinel (CoAl2O4) is produced at higher temperatures or when the Co/Al ratio is 0.5. The XRD patterns of CoAl2O4, Co2AlO4 and Co3O4, are very similar because they share the same spinel cubic structure (space group Fd3m) differing only slightly in the lattice size. It has been demonstrated that Raman and XRD can be used to distinguish between inverse and normal spinels while FT-IR and EDS are useful for assessing the purity of the powders produced. As predicted by group theory, five Raman and four IR active vibrations were evident in the results. Chemistry unrestricted 2013-09-07T17:16:42Z 2009-12-08 2013-09-07T17:16:42Z 2009-09-02 2009-12-08 2009-11-29 Dissertation Mwenesongole, EM 2008, A Raman- and XRD study of the crystal chemistry of cobalt blue, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/29925 > E1500/ag http://hdl.handle.net/2263/29925 http://upetd.up.ac.za/thesis/available/etd-11292009-214916/ © 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Raman spectroscopy Cobalt aluminate spinels Crystal chemistry of cobalt blue Xrd X-ray powder diffraction UCTD A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title | A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title_full | A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title_fullStr | A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title_full_unstemmed | A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title_short | A Raman- and XRD study of the crystal chemistry of cobalt blue |
| title_sort | raman and xrd study of the crystal chemistry of cobalt blue |
| topic | Raman spectroscopy Cobalt aluminate spinels Crystal chemistry of cobalt blue Xrd X-ray powder diffraction UCTD |
| url | http://hdl.handle.net/2263/29925 http://upetd.up.ac.za/thesis/available/etd-11292009-214916/ |