Crystallization Kinetics of LaF3 Nanocrystals in an Oxyfluoride Glass

Nanocrystallization of LaF3 in a glass of composition 55SiO2–20Al2O3–15Na2O–10LaF3 (mol%) has been achieved by heat treatment above the glass transition temperature. A maximum crystal size of 14 nm has been attained, with the crystalline fraction and crystal size dependent on the time and temperatur...

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Published inJournal of the American Ceramic Society Vol. 94; no. 8; pp. 2420 - 2428
Main Authors de Pablos-Martín, Araceli, Hémono, Nicolas, Mather, Glenn C., Bhattacharyya, Sommnath, Höche, Thomas, Bornhöft, Hansjörg, Deubener, Joachim, Muñoz, Francisco, Durán, Alicia, Pascual, Maria J.
Format Journal Article
LanguageEnglish
Published Malden, USA Blackwell Publishing Inc 01.08.2011
Subjects
Crystallization
Crystals
Enrichment
Glass
Heat treatment
Lanthanum fluorides
Nanocrystals
Networks
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Summary:Nanocrystallization of LaF3 in a glass of composition 55SiO2–20Al2O3–15Na2O–10LaF3 (mol%) has been achieved by heat treatment above the glass transition temperature. A maximum crystal size of 14 nm has been attained, with the crystalline fraction and crystal size dependent on the time and temperature of thermal treatment. The effect of lanthanum fluoride crystallization is noticeable from the microstructural and compositional changes in the glass matrix, which have been studied using several techniques, including viscosity, dilatometry, X‐ray diffraction, and quantitative Rietveld refinement, transmission electron microscopy, and differential scanning calorimetry. The crystallization mechanism is shown to occur via regions of La‐ and Si‐phase separation in the glass, from which the fluoride crystals develop during heat treatment. The interface between the glass matrix and the crystals in the demixed ranges is enriched in network formers, mainly SiO2, creating a viscous barrier, which inhibits further crystal growth and limits the crystal size to the nanometric range.
Bibliography:ark:/67375/WNG-KT3JJPZK-R
istex:F8A01D955D19CE93D56C15DF3E315B86A2FEE999
ArticleID:JACE4547
L. Pinckney—contributing editor
The authors acknowledge the financial support of Project INTERCONY, Contract No. NMP4‐CT‐2006‐033200, from Framework 6 of the European Union, the CSIC incorporation intramural project 2007 60I002, and the CiCyt project MAT 2010‐20459. A. De Pablos‐ Martín is grateful to CSIC for a JAE contract.
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ISSN:0002-7820
1551-2916
DOI:10.1111/j.1551-2916.2011.04547.x