Ferroelastic Behavior of LaCoO<sub>3</sub>‐Based Ceramics

Kleveland, Kjersti; Orlovskaya, Nina; Grande, Tor; Moe, Anne; Einarsrud, Mari‐Ann; Breder, Kristin; Gogotsi, G. A.

doi:10.1111/j.1151-2916.2001.tb00953.x

Cited by 61 publications

(43 citation statements)

References 27 publications

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“…The use of diffraction in the characterization of domain switching is not exclusive to piezoelectric materials. Other oxide materials exhibit this phenomenon including zirconia-containing ceramics [76][77][78] and lanthanum oxide ceramics [79][80][81]. Domain switching of 90°domains in perovskite tetragonal ceramics is demonstrated through an intensity interchange between the 002 and 200 peaks.…”

Section: Domain Switchingmentioning

confidence: 90%

The use of diffraction in the characterization of piezoelectric materials

Jones

2007

J Electroceram

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X-ray and neutron diffraction have become powerful characterization tools in materials research. Their leading use in the characterization of piezoelectric ceramics includes the determination of structure, phase evolution, crystallographic texture, and lattice strain. The inherent electromechanical coupling of piezoelectric materials also allows the direct characterization of the converse piezoelectric effect. New advances in diffraction capabilities have recently enabled new problem solutions within this field. For example, the use of microdiffraction has the potential to characterize structural defects including cracks and domain walls. The development of time-resolved techniques has further opened doors to characterizing ferroelectrics in real-time under the application of cyclic electric fields. These recent advances as well as traditional uses of X-ray and neutron diffraction in the characterization of piezoelectric materials and the phenomenon of piezoelectricity are explored in this review. A focus is on characterization of bulk, polycrystalline ceramics, though novel approaches in thin films and single crystals are also reviewed. Challenges and future opportunities are discussed.

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Section: Domain Switchingmentioning

confidence: 90%

The use of diffraction in the characterization of piezoelectric materials

Jones

2007

J Electroceram

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“…The time-dependence of the creep deformation of ferritic alloys for SOFC application reported during tests under constant stress and temperature [59] are for instance not considered. The ferroelastic behaviour [60] reported for LSCF [61] is not implemented. These simplifications are believed acceptable for the present study and will be the subject of future model improvements.…”

Section: Structural Modelmentioning

confidence: 99%

Mechanical reliability and durability of SOFC stacks. Part II: Modelling of mechanical failures during ageing and cycling

Nakajo

Mueller

Brouwer

et al. 2012

International Journal of Hydrogen Energy

107

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Creep Contact analysis a b s t r a c tIntricate relationships between mechanical and electrochemical degradation aspects likely affect the durability of solid oxide fuel cell stacks. This study presents a modelling framework that combines thermo-electrochemical models including degradation and a contact thermo-mechanical model that considers rate-independent plasticity and creep of the components materials and the shrinkage of the nickel-based anode during thermal IntroductionThe end of operation of a solid oxide fuel cell (SOFC) stack ultimately occurs due to the loss of structural integrity of one or several of the cells, as highlighted by several short-stack experiments, e.g [1e4]. We believe this is the result of the accumulation during operation, of physico-chemical alterations inducing a weakening of the materials and interfaces, of plastic and creep deformations, and of the modification of the temperature profile, due to the degradation of the electrochemical performance of the cells. Mechanical issues do not, however, exclusively occur after prolonged use. Inappropriate control during start-up and shut-down and/or following of the electrical power demand, harsh characterisation procedures and thermal cycling can induce discrete failures [5,6]. Despite the evidence of mechanical issues in SOFCs, which are experienced even during laboratory button cell tests, this topic is still receiving limited attention. Efforts are seen as standalone tasks, owing to the different experimental and modelling techniques that are required to gather the essential information, whereas mechanical failures in SOFCs are likely intricately related to chemical and electrochemical aspects.The central component in a stack is the membrane electrode assembly (MEA). As for any multilayered system made of brittle materials, the MEA is prone to failures related to residual * Corresponding author. Tel.: þ41 21 693 35 05.E-mail address: arata.nakajo@epfl.ch (A. Nakajo).Available online at www.sciencedirect.com journal h om epa ge: www.elsev ier.com/locate/he i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 9 2 6 9 e9 2 8 6

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“…Ferroelastic domain switching in LaCoO 3 -materials under mechanical load may increase the fracture toughness of the materials. [11] Microstructure investigations of the ferroelastic domains and switching mechanisms in LaCoO 3 -materials are therefore interesting in order to understand the materials′ mechanical behavior. In this work we report a detailed transmission electron microscopy (TEM) analysis of the ferroelastic domains in LaCoO 3 -based materials.…”

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confidence: 99%

Monoclinic Ferroelastic Domains in LaCoO₃‐Based Perovskites

et al. 2007

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LaCoO 3 -materials have received considerable attention due to their novel magnetic properties [1][2][3] and mixed ionicelectronic conductivity at elevated temperatures leading to exciting applications such as electrodes in solid oxide fuel cells [4] and oxygen permeable membranes.[5] Perovskites such as LaCoO 3 and related materials like LaAlO 3 undergo a displacive phase transition from a paraelastic cubic perovskite with space group Pm 3m at high temperatures to a ferroelastic rhombohedral perovskite with space group R 3c. [6][7][8][9][10] Toughening of the materials is particularly beneficial for membrane applications. Ferroelastic domain switching in LaCoO 3 -materials under mechanical load may increase the fracture toughness of the materials.[11] Microstructure investigations of the ferroelastic domains and switching mechanisms in LaCoO 3 -materials are therefore interesting in order to understand the materials′ mechanical behavior. In this work we report a detailed transmission electron microscopy (TEM) analysis of the ferroelastic domains in LaCoO 3 -based materials. In addition to the well known ferroelastic domains formed by deformation twinning in rhombohedral perovskites, a monoclinic structure is observed by TEM in LaCoO 3 -based materials. The second order improper paraelastic to ferroelastic phase transition in LaCoO 3 -materials doubles the periodicity along the threefold axis, which becomes the unique axis of the rhombohedral ferroelastic state. The phase transition results in the well known deformation twinning (ferroelastic twin domain [12]

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Ferroelastic Behavior of LaCoO₃‐Based Ceramics

Cited by 61 publications

References 27 publications

The use of diffraction in the characterization of piezoelectric materials

The use of diffraction in the characterization of piezoelectric materials

Mechanical reliability and durability of SOFC stacks. Part II: Modelling of mechanical failures during ageing and cycling

Monoclinic Ferroelastic Domains in LaCoO₃‐Based Perovskites

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Ferroelastic Behavior of LaCoO3‐Based Ceramics

Cited by 61 publications

References 27 publications

The use of diffraction in the characterization of piezoelectric materials

The use of diffraction in the characterization of piezoelectric materials

Mechanical reliability and durability of SOFC stacks. Part II: Modelling of mechanical failures during ageing and cycling

Monoclinic Ferroelastic Domains in LaCoO3‐Based Perovskites

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Ferroelastic Behavior of LaCoO₃‐Based Ceramics

Monoclinic Ferroelastic Domains in LaCoO₃‐Based Perovskites