Lattice distortion effect on electrical properties of GDC thin films: Experimental evidence and computational simulation

Lee, Kyung-Ryul; Ahn, Kook Young; Chung, Yong‐Chae; Lee, Jong-Ho; Yoo, Han‐Ill

doi:10.1016/j.ssi.2012.10.007

Cited by 26 publications

(32 citation statements)

References 56 publications

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“…From ab initio calculation results, higher activation energy for oxygen ion migration in stressed GDC thin films was expected by considering the consequential atomic positions, bonding lengths, and angles in the stressed ceria lattice. The calculated activation energies at different dilative strain values in the lateral direction were agreed with the experimental results [193].…”

Section: Gadolinia-doped Ceriasupporting

confidence: 83%

“…The Arrhenius plots and activation energy as a function of film thickness of the samples are shown in Fig. 6.14 [193]. The oxygen partial pressure measurements confirmed that the conductivities of these samples are pure ionic.…”

Section: Gadolinia-doped Ceriamentioning

confidence: 68%

“…The grain interior (GI) conductivity of the half-cell fabricated in this study was 0.1 S cm À1 at 500 C, which is well-desired for IT-SOFC [187]. Lee et al have carried out an experimental study combined with theoretical simulations to understand the effect of mechanical strain on the electrical properties of GDC thin films [193]. They deposited epitaxial GDC(111) thin films on Al 2 O 3 (0001) substrates by varying the film thickness from 50 to 400 nm.…”

Section: Gadolinia-doped Ceriamentioning

confidence: 96%

“…These changes were mainly attributed to the lattice strain associated with film thickness. The strain state of this system is rather complex with compressive strain in the lateral direction and tensile stress in the vertical direction, thus a new atomistic migration model was proposed to explain the strain effects on the electrical properties of GDC thin films [193]. From ab initio calculation results, higher activation energy for oxygen ion migration in stressed GDC thin films was expected by considering the consequential atomic positions, bonding lengths, and angles in the stressed ceria lattice.…”

Section: Gadolinia-doped Ceriamentioning

confidence: 99%

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State-of-the-Art Thin Film Electrolytes for Solid Oxide Fuel Cells

Nandasiri

Thevuthasan

2015

Thin Film Structures in Energy Applications

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State-of-the-art solid oxide fuel cells (SOFC) are among the main candidates for clean energy technology due to their high efficiency, fuel flexibility, low air pollution, and minimal greenhouse gas emission. However, high operational temperature of SOFC is a greater challenge in commercialization of these devices for low cost and portable applications. High temperature operation of SOFC degrades its performance with aging, limits the selection of materials for fuel cell components, and increases the fabrication cost. Thus, there have been enormous efforts to improve the properties of existing materials and develop new materials for SOFC components in order to lower the operating temperature of SOFC. Recent advances in thin film technology have also been utilized to develop new materials with improved properties for SOFC. One of the key components in SOFC is the electrolyte and several research groups are working on developing new electrolyte materials. In this chapter, we will discuss the recent advances in thin film SOFC electrolytes. This extensive discussion includes the evolution of doped ceria, doped zirconia, and multilayer hetero-structured thin film electrolytes. The newly developed nanoscale thin films and multilayer hetero-structures with improved oxygen ionic conductivity will have significant impact on SOFC devices. Introduction Background of Solid Oxide Fuel Cells (SOFC)The latest U.S. energy reviews revealed that more than 80 % of the energy consumed in the world is still produced by non-renewable energy sources such as petroleum, natural gas, and coal [1]. Moreover, it is projected that world energy consumption will grow by 56 % from 2010 to 2040. Therefore, from a long-term energy perspective, clean energy technologies are needed to utilize primary energy

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Section: Gadolinia-doped Ceriasupporting

confidence: 83%

Section: Gadolinia-doped Ceriamentioning

confidence: 68%

Section: Gadolinia-doped Ceriamentioning

confidence: 96%

Section: Gadolinia-doped Ceriamentioning

confidence: 99%

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State-of-the-Art Thin Film Electrolytes for Solid Oxide Fuel Cells

Nandasiri

Thevuthasan

2015

Thin Film Structures in Energy Applications

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“…Crystallographically narrow coherent EC b /SE-AdSIC heterojunctions with the variation of  value ~0.5eV/nm for which stresses and corresponding deformations spread from the boundary to a distance not longer than several lattice parameters [29,30].…”

Section: Objects and Conditions Of Computer Experimentsmentioning

confidence: 99%

Maxwell displacement current and nature of Jonsher’s “universal” dynamic response in nanoionics

Despotuli

Андреева

2014

Ionics

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New notion -Maxwell displacement current on potential barrier -is introduced in the structuredynamic approach of nanoionics for description of collective phenomenon: coupled ion-transport and dielectric-polarization processes occurring during ionic space charge formation and relaxation in non-uniform potential relief. We simulate the processes: (i) in an electronic conductor/advanced superionic conductor (AdSIC) ideally polarizable coherent heterojunction, (ii) in a few strained monolayers of solid electrolyte (SE) located between two AdSICs forming coherent interfaces with SE. We prove the sum of ionic current over any barrier and Maxwell displacement current through the same barrier is equal to the current of current generator.-Universal‖ dynamic response, Re*()   n (n < 1), was found for frequency-dependent conductivity *() for case (ii) with an exponential distribution of potential barrier heights in SE. The nature of phenomenon is revealed. The amplitudes of non-equilibrium ion concentrations (and induced voltages) in space charge region of SE change approximately as   -1 . Amplitudes yield a main linear contribution to Re*(). The deviation from linearity is provided by the cosine of phase shift  between current and voltage in SE-space charge but cos depends relatively slightly on  (near constant loss effect) for coupled ion-transport and dielectric-polarization processes.The canonical physical-mathematical formalism for the description of ion transport in solids [1] is based on the concept of a regular crystalline potential relief, i.e. the heights  of potential barriers are const. As a consequence, ion-transport characteristics (mean-square displacement, diffusion coefficient, mobility, activation energy) have a clear physical meaning only at averaging in the scale much exceeding the length of an elementary ion jump. However, the variation of  with a space coordinate x can be considerable in objects of solid state ionics. For example, local regions with  variation about 1 eV/nm exist in disordered solid electrolytes (SE) [2][3][4] and in crystals of superionic conductors (SIC) [5]. Various degrees of ordering occur near surfaces and in the region of interphase and intercrystalline boundaries [6] where specific ion dynamics can arise on the nanoscale [7] due to a non-uniform potential relief. The interface structure exhibits itself in, e.g., frequency-capacitance characteristics of EC/SIC heterojunctions [8][9][10]. The classification of solid ionic conductors [8-10] distinguishes a class of advanced superionic conductors (AdSIC) among SE and SIC because AdSIC-crystal structure is close to optimal for fast ion transport (FIT). This crystal structure determines the record high level of iontransport characteristics. The FIT structure represents a rigid sub-lattice of immobile ions in which there are the crystallographic positions interconnected with each other by low potential barriers (conduction tunnels) for hopping mobile ions. The number of such positions is several times larger ...

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Scalable Oxygen‐Ion Transport Kinetics in Metal‐Oxide Films: Impact of Thermally Induced Lattice Compaction in Acceptor Doped Ceria Films

Rupp

Fabbri

Marrocchelli

et al. 2014

Adv Funct Materials

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In this paper, we focus on the effect of processing‐dependent lattice strain on oxygen ion conductivity in ceria based solid electrolyte thin films. This is of importance for technological applications, such as micro‐SOFCs, microbatteries, and resistive RAM memories. The oxygen ion conductivity can be significantly modified by control of lattice strain, to an extent comparable to the effect of doping bulk ceria with cations of different diameters. The interplay of dopant radii, lattice strain, microstrain, anion‐cation near order and oxygen ion transport is analyzed experimentally and interpreted with computational results. Key findings include that films annealed at 600 °C exhibit lattice parameters close to those of their bulk counterparts. With increasing anneal temperature, however, the films exhibited substantial compaction with lattice parameters decreasing by as much as nearly 2% (viz, Δd600–1100 °C: –1.7% (Sc+3) > –1.5% (Gd+3) > –1.2% (La+3)) for the annealing temperature range of 600–1100 °C. Remarkably 2/3rd of the lattice parameter change obtained in bulk ceria upon changing the acceptor diameter from the smaller Sc to larger La, can be reproduced by post annealing a film with fixed dopant diameter. While the impact of lattice compaction on defect association/ordering cannot be entirely excluded, DFT computation revealed that the main effect appears to result in an increase in migration energy and consequent drop in ionic conductivity. As a consequence, it is clear that annealing procedures should be held to a minimum to maintain the optimum level of oxygen ion conductivity for energy‐related applications. Results reveal also the importance to understand the role of electro‐chemo‐mechanical coupling that is active in thin film materials.

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Lattice distortion effect on electrical properties of GDC thin films: Experimental evidence and computational simulation

Cited by 26 publications

References 56 publications

State-of-the-Art Thin Film Electrolytes for Solid Oxide Fuel Cells

State-of-the-Art Thin Film Electrolytes for Solid Oxide Fuel Cells

Maxwell displacement current and nature of Jonsher’s “universal” dynamic response in nanoionics

Scalable Oxygen‐Ion Transport Kinetics in Metal‐Oxide Films: Impact of Thermally Induced Lattice Compaction in Acceptor Doped Ceria Films

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