Change search
ReferencesLink to record
Permanent link

Direct link
Rare Earth Oxide Nanopowder (RE = Nd, Eu, Gd, Ho, Y, Yb) by Combustion Synthesis, Sulfation and Calcination: Role of the Initial Structure
2011 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A novel method for synthesising rare earth oxide (RE2O3) nanopowder was applied to several rare earths including Nd, Eu, Gd, Ho, Y and Yb. The process was successful in producing homogeneous, fine dispersed and deagglomerated powder particles with uniform morphology for all rare earth oxides, except neodymia. In the first process step, rare earth nitrate solutions were mixed with glycine and subsequently heated in a furnace. Glycine acted as fuel to initiate the combustion synthesis (SHS) in order to obtain nanocrystalline and weakly agglomerated particles. Powder samples were produced at three different glycine-to-nitrate ratios (G/N), involving stoichiometric ratio (G/N = 0.56) and two fuel lean ratios (0.32 and 0.25). As a consequence of low combustion temperature at fuel lean ratios were carbonate structures found and their formation was correlated to the size of the rare earth cation. Resulting cellular structures were analysed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The cellular structure is unsuitable to be processed to a final product. The resulting powder has a very large specific volume and is comprised of strongly agglomerated crystallites, which renders pressing and sintering of these structures difficult. Therefore an additional synthesis step was employed with the addition of ammonium sulfate and calcination for 4 h in a tube furnace at 1100°C. In order to understand the influence of the initial, cellular structure on the morphological and microstructural powder properties different sulfate concentrations were used. Samples were characterized by XRD and scanning electron microscopy (SEM). The average crystallite size increased during calcination from below 15 nm in the initial structure to 50 nm in the final product. However, the resulting particles were loosely agglomerated. A benefit of sulfate-doped rare earth compounds under heat treatment is the formation of nearly isotropic surfaces, which might be related to the promotion of surface diffusion and partial inhibition of densifying transport mechanisms such as volume diffusion.

Place, publisher, year, edition, pages
2011. , 43 p.
Keyword [en]
Physics Chemistry Maths, rare earth, neodymia, europia, gadolinia, holmia, yttria, ytterbia, neodymium oxide, europium oxide, gadolinium oxide, holmium oxide, yttrium oxide, ytterbium oxide, powder, combustion, synthesis, glycine, nitrate, shs, sulfation, sulfate, calcination, nano, particles, rare earth oxide, Nd, Eu, Gd, Ho, Y, Yb, Nd2O3, Eu2O3, Gd2O3, Ho2O3, Y2O3, Yb2O3, RE2O3, oxide
Keyword [sv]
Fysik, Kemi, Matematik
URN: urn:nbn:se:ltu:diva-59471Local ID: ffc153f2-7939-432b-acb0-6bb0415a21c7OAI: diva2:1032859
Subject / course
Student thesis, at least 30 credits
Educational program
Chemical Engineering, master's level
Validerat; 20110923 (anonymous)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

Open Access in DiVA

fulltext(39153 kB)0 downloads
File information
File name FULLTEXT02.pdfFile size 39153 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Agthe, Michael

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

ReferencesLink to record
Permanent link

Direct link