The structure of a propagating MgAl2O4/MgO interface: linked atomic- and μ-scale mechanisms of interface motion

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F16%3A10327827" target="_blank" >RIV/00216208:11310/16:10327827 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1080/14786435.2016.1205233" target="_blank" >http://dx.doi.org/10.1080/14786435.2016.1205233</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1080/14786435.2016.1205233" target="_blank" >10.1080/14786435.2016.1205233</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The structure of a propagating MgAl2O4/MgO interface: linked atomic- and μ-scale mechanisms of interface motion

Popis výsledku v původním jazyce

To understand how a new phase forms between two reactant layers, MgAl2O4 (spinel) has been grown between MgO (periclase) and Al2O3 (corundum) single crystals under defined temperature and load. Electron backscatter diffraction data show a topotaxial relationship between the MgO reactant and the MgAl2O4 reaction product. These MgAl2O4 grains are misoriented from perfect alignment with the MgO substrate by similar to 2-4 degrees, with misorientation axes concentrated in the interface plane. Further study using atomic resolution scanning transmission electron microscopy shows that in 2D the MgAl2O4/MgO interface has a periodic configuration consisting of curved segments (convex towards MgO) joined by regularly spaced misfit dislocations occurring every similar to 4.5nm (similar to 23 atomic planes). This configuration is observed along the two equivalent [100] directions parallel to the MgAl2O4/MgO interface, indicating that the 3D geometry of the interface is a grid of convex protrusions of MgAl2O4 into MgO. At each minimum between the protrusions is a misfit dislocation. This geometry results from the coupling between long-range diffusion, which supplies Al3+ to and removes Mg2+ from the reaction interface, and interface reaction, in which climb of the misfit dislocations is the rate-limiting process. The extra oxygen atoms required for dislocation climb were likely derived from the reactant MgO, leaving behind oxygen vacancies that eventually form pores at the interface. The pores are dragged along by the propagating reaction interface, providing additional resistance to interface motion. The pinning effect of the pores leads to doming of the interface on the scale of individual grains.

Název v anglickém jazyce

The structure of a propagating MgAl2O4/MgO interface: linked atomic- and μ-scale mechanisms of interface motion

Popis výsledku anglicky

To understand how a new phase forms between two reactant layers, MgAl2O4 (spinel) has been grown between MgO (periclase) and Al2O3 (corundum) single crystals under defined temperature and load. Electron backscatter diffraction data show a topotaxial relationship between the MgO reactant and the MgAl2O4 reaction product. These MgAl2O4 grains are misoriented from perfect alignment with the MgO substrate by similar to 2-4 degrees, with misorientation axes concentrated in the interface plane. Further study using atomic resolution scanning transmission electron microscopy shows that in 2D the MgAl2O4/MgO interface has a periodic configuration consisting of curved segments (convex towards MgO) joined by regularly spaced misfit dislocations occurring every similar to 4.5nm (similar to 23 atomic planes). This configuration is observed along the two equivalent [100] directions parallel to the MgAl2O4/MgO interface, indicating that the 3D geometry of the interface is a grid of convex protrusions of MgAl2O4 into MgO. At each minimum between the protrusions is a misfit dislocation. This geometry results from the coupling between long-range diffusion, which supplies Al3+ to and removes Mg2+ from the reaction interface, and interface reaction, in which climb of the misfit dislocations is the rate-limiting process. The extra oxygen atoms required for dislocation climb were likely derived from the reactant MgO, leaving behind oxygen vacancies that eventually form pores at the interface. The pores are dragged along by the propagating reaction interface, providing additional resistance to interface motion. The pinning effect of the pores leads to doming of the interface on the scale of individual grains.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DB - Geologie a mineralogie

OECD FORD obor

—

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Philosophical Magazine

ISSN

1478-6435

e-ISSN

—

Svazek periodika

96

Číslo periodika v rámci svazku

23

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

16

Strana od-do

2488-2503

Kód UT WoS článku

000381288000006

EID výsledku v databázi Scopus

2-s2.0-84978523923