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您的检索式：作者名="K.S.N.Vikrant"
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| 1 | Charged grain boundary transitions in ionic ceramics for energy applications显示文摘Surfaces and interfaces in ionic ceramics play a pivotal role in defining the transport limitations in many of the existing and emerging applications in energy-related systems such as fuel cells,rechargeable batteries,as well as advanced electronics such as those found in semiconducting,ferroelectric,and piezotronic applications.Here,a variational framework has been developed to understand the effects of the intrinsic and extrinsic ionic species and point defects on the structural and electrochemical stability of grain boundaries in polycrystalline ceramics.The theory predicts the conditions for the interfacial electrochemical and structural stability and phase transitions of charged interfaces and quantifies the properties induced by the broad region of electrochemical influence in front of a grain boundary capable of spanning anywhere from a few angtroms to entire grains.We demonstrate the validity of this theory for Y_(x)Zr_(1−x)O_(2−x/2),cubic yttria stabilized zirconia. | K.S.N.Vikrant R.Edwin García | 2019 | npj Computational Materials2019，，1： | 4 |
| 2 | Electrochemical drag effect on grain boundary motion in ionic ceramics显示文摘The effects of drag imposed by extrinsic ionic species and point defects on the grain boundary motion of ionic polycrystalline ceramics were quantified for the generality of electrical,chemical,or structural driving forces.In the absence of,or for small driving forces,the extended electrochemical grain boundary remains pinned and symmetrically distributed about the structural interface.As the grain boundary begins to move,charged defects accumulate unsymmetrically about the structural grain boundary core.Above the critical driving force for motion,grain boundaries progressively shed individual ionic species,from heavier to lighter,until they display no interfacial electrostatic charge and zero Schottky potential.Ionic p-n junction moving grain boundaries that induce a finite electrostatic potential difference across entire grains are identified for high velocity grains.The developed theory is demonstrated for Fe-doped SrTiO_(3).The increase in average Fe concentration and grain boundary crystallographic misorientation enhances grain boundary core segregation and results in thick space charge layers,which leads to a stronger drag force that reduces the velocity of the interface.The developed theory sets the stage to assess the effects of externally applied fields such as temperature,electromagnetic fields,and chemical stimuli to control the grain growth for developing textured,oriented microstructures desirable for a wide range of applications. | K.S.N.Vikrant Wolfgang Rheinheimer R.Edwin García | 2020 | npj Computational Materials2020，，1： | 0 |
| 3 | Flash sintering incubation kinetics显示文摘The microstructural mechanisms leading to onset of the flash sintering are demonstrated experimentally and theoretically for Yttria Stabilized Zirconia,YSZ.Three regimes leading to flash event are identified:(1)Radiation-dominated regime,where the oven controls the heating of the sintered sample,and a small subset of particle-particle contacts and surfaces of the green body define percolative paths for the charge to flow along and across the interfaces;(2)Transition regime,where charge transport is suppressed across particle contact misorientations and deflects to surficial and small angle particle contact misorientations.As a result,internal Joule heating takes over externally-driven radiation heating.Finally,(3)Percolative regime,where the concentration of oxygen vacancies drastically increases at particle contacts,surfaces,and triple junctions,and enables charge to flow through multiple paths,generating large amounts of Joule heating,resulting in the onset of a flash event.The validated theory sets the stage to rationalize the microstructural evolution and charge transport on a ceramic green body during flash sintering. | K.S.N.Vikrant Han Wang Aniruddha Jana Haiyan Wang R.Edwin García | 2020 | npj Computational Materials2020，，1： | 0 |
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