Mechanical properties and defect chemistry

Lubomirsky, Igor

doi:10.1016/j.ssi.2006.01.020

Cited by 26 publications

(10 citation statements)

References 15 publications

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“…The crystal radius of Pr 3+ (126.6 pm) is much larger that of the host Ce 4+ (111 pm), whereas Pr 4+ and Lu 3+ , despite the difference in their charge, have crystal radii close to that of Ce 4+ : 110 pm and 117.7 pm, respectively 33. Our data demonstrate 1) that the dopant radius, rather than the oxygen vacancy concentration, is a primary determinant of the elastic modulus; 2) that the rearrangement of point defects is the major cause of creep at room temperature; and 3) that nanoindentation is a practical technique for identifying materials with labile point defects,26 which may potentially indicate practical functionality such as high ionic conductivity,1, 34, 35 large electrostriction,7 and inelasticity 36…”

Section: Introductionmentioning

confidence: 68%

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

Korobko

Kim

et al. 2013

Adv Funct Materials

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The influence of dopant size and oxygen vacancy concentration on the room temperature elastic modulus and creep rate of ceria doped with Pr4+, Pr3+, Lu3+, and Gd3+, is investigated using a nanoindentation technique. Measurements are conducted with both fast (15 mN s−1) and slow (0.15 mN s−1) loading modes, including a load‐hold stage at 150 mN of 8 s and 30 s, respectively. Based on the data obtained using the fast loading mode, it is found that: 1) the dopant size is a primary determinant of the elastic modulus—the larger dopants (Pr3+ and Gd3+) produce lower unrelaxed moduli which are independent of the oxygen vacancy concentration. 2) The rearrangement of point defects is the major source of room temperature creep observed during load‐hold. Pr3+‐ and Gd3+‐doped ceria display the higher creep rates: due to their large size, they repel oxygen vacancies (VO), thereby promoting the formation of O7–CeCe–VO complexes that are capable of low temperature rearrangement. Lower creep rates are observed for Pr4+‐ and Lu3+‐doped ceria: the former has no vacancies and the latter, immobile vacancies. 3) Nanoindentation is a practical technique for identifying materials with labile point defects, which may indicate useful functionality such as high ionic conductivity, large electrostriction, and inelasticity.

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Section: Introductionmentioning

confidence: 68%

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

Korobko

Kim

et al. 2013

Adv Funct Materials

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“…In literature, very few studies are devoted to the thermal stability of shaped materials. As pointed out by Lubomirsky [18], application of an external stress could have a non-negligible influence on the defects equilibrium in ionic conductors with high concentration of point defects. Thus, ceramic could expand or contract as the defects equilibrium changes, inducing mechanical stress between device components or in extreme case fracture of the membrane.…”

Section: Discussionmentioning

confidence: 96%

Comprehensive survey of Nd3+ substitution In La2Mo2O9 oxide-ion conductor

Corbel

Durand

Lacorre

2009

Journal of Solid State Chemistry

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“…Lubomirsky et al [16] have pointed out that, in ionic conductors with a high concentration of point defects, application of an external stress could have a non-negligible influence on the defects equilibrium. Suspecting that sample shaping/sintering might have a similar effect on the orderdisorder phase transitions of our LAMOX compounds, we have carried out several temperature-controlled diffraction studies on different kinds of samples with composition La 1.92 Ca 0.08 Mo 2 O 8.96 (4 mol-% Ca).…”

Section: Ceramic Samplesmentioning

confidence: 99%

Complex Effect of Partial Substitution of La³⁺ by Ca²⁺ on the Stability of Fast Oxide‐Ion Conductor La₂Mo₂O₉

et al. 2008

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Keywords: Ceramics / Phase transitions / Reversible demixing / Metastability / Temperature-controlled X-ray diffraction Demixing/recombination and metastability phenomena are observed in the La 2-2x Ca 2x Mo 2 O 9-x solid solutions of LAMOX-type fast oxide-ion conductors (0.005 Յ x Յ 0.05). The demixing process is more visible at high Ca content. The effects of composition, sample shape (powders with two degrees of fineness, ceramic pellets, single crystals) and thermal history are studied by using high-temperature X-ray diffraction, differential scanning calorimetry (DSC) and polarized microscopy. All these parameters are shown to have an influence on the stability of, and transformations between, the ordered α and the disordered β forms of the LAMOX compounds. Powder samples with low Ca content (x = 0.01, 0.02) have been stabilized in the α form, and powder samples with higher Ca content (x = 0.03, 0.04, 0.05) are in the β form. Upon heating, the low-Ca-content compounds (x = 0.01 and x = 0.02) exhibit the α/β transition, whereas those with higher Ca content (x = 0.03 and x = 0.04) show a succession of β/

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Mechanical properties and defect chemistry

Cited by 26 publications

References 15 publications

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

Comprehensive survey of Nd3+ substitution In La2Mo2O9 oxide-ion conductor

Complex Effect of Partial Substitution of La³⁺ by Ca²⁺ on the Stability of Fast Oxide‐Ion Conductor La₂Mo₂O₉

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Mechanical properties and defect chemistry

Cited by 26 publications

References 15 publications

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

The Role of Point Defects in the Mechanical Behavior of Doped Ceria Probed by Nanoindentation

Comprehensive survey of Nd3+ substitution In La2Mo2O9 oxide-ion conductor

Complex Effect of Partial Substitution of La3+ by Ca2+ on the Stability of Fast Oxide‐Ion Conductor La2Mo2O9

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Complex Effect of Partial Substitution of La³⁺ by Ca²⁺ on the Stability of Fast Oxide‐Ion Conductor La₂Mo₂O₉