Structural disorder and phase transitions in ZrO2-Y2O3 system

Feinberg, Alec; Perry, C. H.

doi:10.1016/0022-3697(81)90032-9

Cited by 282 publications

(165 citation statements)

References 22 publications

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“…Such a phase transition, known as partial melting, can be driven by soft phonon modes, lattice strain, or structural disorder. Previous studies [11][12][13] showed that ionic conductivity could be improved significantly by tuning these driving forces. For practical applications, it is crucial that the recently synthesized anti-perovskites exhibit good thermodynamic and electrochemical stability.…”

mentioning

confidence: 99%

Ab initiostudy of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

2013

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Recently, a family of halogen-based Li-rich anti-perovskites was synthesized [J. Am. Chem. Soc. 134, 15042 (2012)], and the measured superionic conductivity makes these materials promising candidates as solid electrolytes for applications in Li-ion and Li-air batteries. This discovery raises several pressing issues on the fundamental physics concerning the thermodynamic and electrochemical stability of the synthesized materials and the mechanism of the observed superionic Li + transport. Here we study the reported anti-perovskites Li3OCl, Li3OBr and their mixed compounds using first-principles density functional theory and molecular dynamics simulations. Our calculations show that these materials are thermodynamically metastable. Their large electronic band gaps and chemical stability against electrodes suggest the excellent electrochemical performance, which bodes well for the use in potentially harsh working conditions in practical battery applications. The calculated low activation enthalpy for Li ion migration well below the crystal melting temperature and superionic transport near the Li sub-lattice melting state explain the experimentally observed phenomena. Our study identifies mobile Li vacancies and anion disorder as the primary driving mechanisms for superionic Li + conductivity in the anti-perovskites. The present work unveils essential working principles of the Li-rich anti-perovskites, which are crucial to further exploration, development, and application of these and other charge-inverted materials with tailored properties.

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mentioning

confidence: 99%

Ab initiostudy of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

2013

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“…1) and the same InO 1.5 concentration. Moreover, the Raman spectrum of the 9InTaSZ sample does not provide evidence for the existence of the c-phase 32,35,36,39 , since cubic symmetry must theoretically be reflected by a single broad band between 400 and 670 cm -1 , which is not observed in Fig. 3c. A comparison of the XRD and Raman results reveals that alloying 9 mol% of InO 1.5 into zirconia and dehydrated by EW/AD provides the complete stabilization of the t-phase.…”

Section: Crystallization and Phase Formationmentioning

confidence: 87%

“…In the case of the 9InTaSZ sample (Fig. 3c), bands at 147, 276, 310, 470, and 637 cm -1 represent 5 of the 6 Raman-active modes predicted by group theory for tetragonal symmetry 36,38,39 . Similar Raman spectra for YSZ were recorded by Ghosh et al 33 .…”

Section: Crystallization and Phase Formationmentioning

confidence: 92%

Synthesis by coprecipitation of india-stabilized zirconia and codoping with MoO3, WO3, TaO2.5, or NbO2.5 for application as thermal barrier coatings

Piva

Morelli

2016

Mat. Res.

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Coprecipitation synthesis of nanocrystalline india-stabilized zirconia with high surface area and codoping with MoO 3 , WO 3 , TaO 2.5 , or NbO 2.5 is reported. The concentration of codopants was defined by the charge-compensating mechanism. Ethanol washing followed by azeotropic distillation and freeze drying were compared as dehydration techniques for the gels. As determined by XRD and Raman scattering, 9 mol% of InO 1.5 plus charge-compensating dopants is sufficient to completely stabilize the high-temperature tetragonal phase of zirconia. The effect of alloying hexavalent and pentavalent oxides was secondary compared to the InO 1.5 concentration in the retention of the tetragonal structure. Improved specific surface area of 106.1 m 2 g -1 and crystallite size between 8 and 9 nm were achieved through ethanol washing and subsequent azeotropic distillation even after calcination at 600 ºC. This result is attributed to the effect of the incorporation of ethoxy and butoxy groups after the treatment of the gels in organic medium, as detected by FT-IR spectroscopy and DSC/TG.

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“…La figura 10 muestra uno de los espectros representativos de las superficies de fractura (en el entorno de su lugar de inicio de la grieta) de las muestras ensayadas a 600 ºC en aire. A pesar del ruido de fondo introducido por la fuerte emisión del ion Er 3+ , los cinco picos característicos de la circona tetragonal (640, 465, 325, 260 y 150 cm -1 ) se aprecian claramente, mientras que los 14 picos esperados para la circona monoclínica no se encontraron en ninguna de las muestras [20]. Los espectros registrados a partir del resto de muestras ensayadas mostraron los mismos resultados: no hay evidencia de circona monoclínica hasta el límite de resolución de la técnica, que en nuestro caso sería de capas menores de 40 nm.…”

Section: Discussionunclassified

Degradación ambiental de las propiedades mecánicas de fibras monocristalinas de circona dopada con erbia

Pastor¹,

Ridruejo²,

Llorca³

et al. 2007

Bol. Soc. Esp. Ceram. Vidr.

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Partiendo de fibras monocristalinas de ZrO 2 (Er 2 O 3 ) tetragonal fabricadas por un procedimiento de fusión zonal con láser (LHFZ), se efectuaron ensayos de flexión en los que se medía la resistencia mecánica en función de la temperatura (25 a 800 ºC) y el medio (aire o agua). Los ensayos fueron realizados a distintas velocidades con objeto de establecer la susceptibilidad a las condiciones ambientales. La susceptibilidad ambiental de la ZrO 2 (Y 2 O 3 ) se había asociado siempre a la desestabilización de la fase tetragonal, pero el análisis de las superficies de fractura mediante microscopía electrónica de barrido y espectroscopia Raman confocal muestran una ausencia completa de fase monoclínica en las superficies de fractura de las fibras. Esta ausencia, junto con los ensayos complementarios sobre fibras sometidas a tratamientos de recocido para eliminar las tensiones residuales provenientes del procesado, indican que el crecimiento subcrítico de grieta se debe a un mecanismo de corrosión bajo tensión.Palabras clave: circona, erbia, estructura tetragonal, susceptibilidad al ambiente, crecimiento subcrítico de grieta, corrosión bajo tensión. Environmental degradation of the mechanical properties of single-crystal erbia-doped zircona fibersThe flexure strength of tetragonal ZrO 2 (Er 2 O 3 ) single-crystal monofilaments manufactured by the laser-heated floating zone method was measured as a function of the environment (air vs. water) and temperature (from 25 to 800ºC) at loading rates spanning three orders of magnitude to ascertain their susceptibility to the environmental conditions. These mechanical tests were completed with parallel tests on fully-annealed monofilaments (to relieve the thermal residual stresses induced during growth) and by detailed analysis of the fracture surfaces using scanning electron microscopy and micro-Raman spectroscopy. While environmental susceptibility of ZrO 2 (Y 2 O 3 ) in previous investigations was always associated with the destabilization of the tetragonal phase, monoclinic phase was not detected on the fracture surfaces of the ZrO 2 (Er 2 O 3 ) monofilaments and it was concluded that slow crack growth in this material at high temperature or immersed in water was due to stress-corrosion cracking.Keywords: zircona, erbia, tetragonal structure, environmental susceptibility, slow crack growth, stress-corrosion cracking INTRODUCCIóNLa importancia de la circona como material estructural estriba principalmente en la capacidad de aumentar su tenacidad mediante la transformación de la fase tetragonal -metaestable-en fase monoclínica cuando en el entorno de la punta de la grieta se supera un determinado umbral de tensión. La literatura científica [1-3] ha descrito detalladamente algunos de los factores relevantes, tales como la cantidad y naturaleza de los elementos estabilizantes, el tamaño de grano o la presencia de tensiones residuales. Sin embargo, una de las limitaciones que presentan los materiales cerámicos de circona, de cara a su aplicación industrial es la degradación amb...

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Structural disorder and phase transitions in ZrO2-Y2O3 system

Cited by 282 publications

References 22 publications

Ab initiostudy of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

Ab initiostudy of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

Synthesis by coprecipitation of india-stabilized zirconia and codoping with MoO3, WO3, TaO2.5, or NbO2.5 for application as thermal barrier coatings

Degradación ambiental de las propiedades mecánicas de fibras monocristalinas de circona dopada con erbia

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