Artículo
Structural and kinetic study of phase transitions in LaYSi 2O 7
Autor/es | Fernández Carrión, Alberto José
Escudero Belmonte, Alberto Suchomel, Matthew R. Becerro Nieto, Ana Isabel |
Departamento | Universidad de Sevilla. Departamento de Química Inorgánica |
Fecha de publicación | 2012-08 |
Fecha de depósito | 2024-02-01 |
Publicado en |
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Resumen | Phase transitions in LaYSi 2O 7 have been investigated as a function of temperature using XRD, NMR and TEM. Previously described empirical crystal structure guidelines based on average cation radius in rare-earth RE 2Si ... Phase transitions in LaYSi 2O 7 have been investigated as a function of temperature using XRD, NMR and TEM. Previously described empirical crystal structure guidelines based on average cation radius in rare-earth RE 2Si 2O 7-type disilicates predict a stable tetragonal A-LaYSi 2O 7 polymorph at temperatures below 1500°C. This study demonstrates that A-LaYSi 2O 7 is not thermodynamically stable at these temperatures and suggests that guidelines based on average cation size do not accurately describe the equilibrium behaviour of this silicate system. The A to G-type polymorph transition is extremely sluggish; complete transformation requires ~250h at 1200°C, and more than 3 weeks of calcination at 1100°C. This observation is important when this type of material is used as environmental barrier coating (EBC) of advanced ceramics. Analysis of XRD and TEM data reveal complete substitution of Y and La on the rare-earth cation sites in both LaYSi 2O 7 polymorphs, but indicate preferential site occupancies in the G-type polymorph. |
Agencias financiadoras | Dirección General de Investigación Científica y Técnica (DGICYT). España Junta de Andalucía |
Identificador del proyecto | CTQ2010-14874/BQU
FQM-6090 |
Cita | Fernández Carrión, A.J., Escudero Belmonte, A., Suchomel, M.R. y Becerro Nieto, A.I. (2012). Structural and kinetic study of phase transitions in LaYSi 2O 7. Journal of the European Ceramic Society, 32 (10), 2477-2486. https://doi.org/10.1016/j.jeurceramsoc.2012.03.009. |
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