Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Synthesis of Yb:Y2O3 nanoparticles and fabrication of transparent polycrystalline yttria ceramics
2005 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

More efficient laser materials are needed for space applications in order to save weight and make cost-savings. The fabrication of polycrystalline ceramic materials is a solution to obtain new compositions with better efficiency. In order to produce a Yb doped Y2O3 laser material, we developed a process to obtain yttrium oxide nanosized particles doped with ytterbium and a sintering method that leads to transparent polycrystalline ceramics. First, nano-powder of yttria was fabricated from a precursor with transient morphology, i.d. yttrium hydroxynitrate platelets that decompose into spherical yttria nano-particles during calcination. The influence of different dewatering methods on such precursors was investigated. Water removal by freeze-drying was shown to be optimal for the production of non- agglomerated nano-particles compared with other methods that involve solvent removal by evaporation. This was attributed to the ability of freeze-drying to avoid the formation of solid bridges, since water is directly removed by sublimation. In a second step, doping with ytterbium was performed. Two precipitation routes were compared: precipitation of hydroxynitrate platelets and precipitation of amorphous carbonate. This latter was shown to allow a better distribution of ytterbium in the yttrium oxide matrix after calcination of the corresponding precursor. This was explained in terms of the good cation mixing in the amorphous particles, while formation of the hydroxynitrate platelets resulted in segregation of ytterbium, probably because a second phase with different ytterbium/yttrium composition precipitates in the first stages of the synthesis. Finally, a method combining pre-sintering in vacuum followed by hot isostatic pressing was shown to be successful to produce transparent yttria ceramics from agglomerated powders with high purity. Pre-sintering in vacuum agglomerates of closely-packed particles enables differential sintering, which is responsible for the complete elimination of porosity in the agglomerates and for the formation of intergranular porosity only. Then, hot isostatic pressing treatment of the pre-sintered samples using the glass-canning technique reactivates sintering and coarsening, which causes almost complete pore elimination. Furthermore, a liquid phase formed during sintering because of pollution from the furnace. This liquid phase is thought of as to have helped densification to some extent. The best transparent ceramic showed a transmittance of 43% at 400 nm.

sted, utgiver, år, opplag, sider
Luleå: Luleå tekniska universitet, 2005. , s. 126
Serie
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2005:29
HSV kategori
Forskningsprogram
Materialteknik
Identifikatorer
URN: urn:nbn:se:ltu:diva-17509Lokal ID: 3b9b8b30-90c8-11db-8975-000ea68e967bOAI: oai:DiVA.org:ltu-17509DiVA, id: diva2:990514
Merknad
Godkänd; 2005; 20061221 (haneit)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2017-11-24bibliografisk kontrollert

Open Access i DiVA

fulltekst(7683 kB)143 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 7683 kBChecksum SHA-512
26c5032885868822d03695d0114db45797ea5de07ab5a1044821aa549cde105be60318763c87297ff05752b4accc81d4794907deb06c9244cb4d56ef58b7d19a
Type fulltextMimetype application/pdf

Personposter BETA

Mouzon, Johanne

Søk i DiVA

Av forfatter/redaktør
Mouzon, Johanne

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 143 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

urn-nbn

Altmetric

urn-nbn
Totalt: 548 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf