Pulsed laser ablation synthesis of magnesiowüstite based phases with special defect clusters, interfaces and internal stress: implications for natural occurrence and engineering applications

Lin, Tsung-Yi; Lin, Shih Pin; Chen, Shuei-Yuan; Shen, Pouyan

doi:10.1039/c4ce02476a

Cited by 5 publications

(7 citation statements)

References 56 publications

(56 reference statements)

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“…Fig. 11 of Lin et al, 2015). The asymmetric tilt boundaries of a single-phase bicrystal have been systematically studied by Yeh et al (2010) using a novel nanofilm method by rotating nanograins.…”

Section: Discussionmentioning

confidence: 99%

On the forbidden and the optimum crystallographic variant of rutile in garnet

et al. 2016

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In many inclusion–host systems with similar oxygen packing schemes, the optimum crystallographic orientation relationship (COR) between the inclusion and the host is mostly determined by matching the similar oxygen sublattices of the two structures. In contrast, the prediction of the optimum COR or even just the rationalization of the observed COR(s) between an inclusion and host with incompatible oxygen sublattices, like rutile–garnet, is not straightforward. The related documentation for such cases is therefore limited. Given the abundant crystallographic data for the rutile–garnet system acquired by transmission electron microscopy and electron backscatter diffraction methods recently, this problem can now be examined in detail for the critical structural factors dictating the selection of optimum COR in such a structurally complicated system. On the basis of the unconstrained three‐dimensional lattice point match and structural polyhedron match calculated for the observed CORs, it becomes clear that the prerequisite of optimum COR for rutile (rt) in garnet (grt) is to have most of their octahedra similarly oriented/inclined in space by aligning ⟨103⟩rt and ⟨111⟩grt for needle extension growth. Further rotation along the ⟨103⟩rt//⟨111⟩grt direction then leads to the energetically most favorable COR‐2 variant with a good lattice point match defined by the coincidence site lattice (CSL) and a good topotaxial match of the constituent polyhedra at the CSL points, leaving unfavorable COR‐1′ in the forbidden zones. This understanding sheds light not only on hierarchical energetics for the selection of inclusion variants in a complicated inclusion–host system, but also on yet‐to‐be‐explored [UVW]‐specific CORs and hetero‐tilt boundaries for composite materials in general.

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Section: Discussionmentioning

confidence: 99%

On the forbidden and the optimum crystallographic variant of rutile in garnet

et al. 2016

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“…6−8 At various levels of dispersion, crystalline MgO particles with iron admixtures are used as pigments, 9 as components for magnetic devices and photovoltaics, 10 and as gas sensors. 11 Beyond dilute solutions in MgO (magnesiowustite), 12 at higher concentrations Fe ions give rise to the annealing-induced nucleation and growth of MgFe 2 O 4 nanoparticles. 13 Thus, thermal processing represents a valuable approach to adjust the particle size and, consequently, to tune the size dependent magnetic properties.…”

Section: ■ Introductionmentioning

confidence: 99%

Stability and Local Environment of Iron in Vapor Phase Grown MgO Nanocrystals

et al. 2017

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Metallocene injection into a metal combustion flame has been used for trapping transition metal ions inside MgO nanocrystals. Vacuum annealing changes the properties of resulting nonequilibrium solids toward thermodynamic equilibrium and provides means to control impurity localization and, as a result, the nanomaterials’ functional properties. By combining structure characterization (X-ray diffraction and transmission electron microscopy) with X-ray absorption spectroscopy and Mössbauer measurements, we tracked valence state and local chemical environment changes of Fe3+ ions inside vapor phase synthesized MgO nanocrystals. At a concentration of (1.5 ± 0.2) at. % Fe about (1400 ± 200) Fe3+ ions are effectively diluted within 12 nm sized nanocubes, where they form complexes between Fe3+ ions and Mg2+ vacancies. Increase of the iron concentration produces additional effects: enhanced ion diffusion and particle coarsening at elevated temperatures, clustering of Fe3+–Mg2+ vacancy complexes and, after annealing to T = 1173 K, the nucleation of a magnesioferrite phase that can be detected by X-ray diffraction for 4 at. % samples. At 3 at. % Fe, corresponding impurity ions induce surface energy changes that have a substantial impact on particle shape. With regard to the functional properties associated with transition metal ions in insulating MgO host lattices, the here presented insights underline that annealing-induced reorganization of oxide nanoparticles provides important parameters to control distribution and localization of impurity ions.

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“…36 As for engineering/industrial implications, the composite oxide nanocondensates in the Co 1−x O-MgO system may have many potential optocatalytic applications taking advantage of the tailored shape and defects different from the undoped cobalt oxides in thin film or bulk, [37][38][39][40] although unfortunately the yields of the particulates/nanocondensates by the present PLA process were too small (mg scale) to study their specific optocatalytic reactions. (Bulk cobalt oxides in rock salt-or spinel-type structure have been used as gas sensors, 41,42 hightemperature solar selective absorbers 38 and electrochromic devices. 39 ) In any case, the densified Mg-doped Co 1−x O and/ or Co 3−δ O 4 spinel with tailored paracrystalline distribution of defect clusters and special interface with space charge are expected to affect charge transfer and hence catalytic activity as a stepwise sensor of oxygen partial pressure at high temperatures and other potential opto-electronic catalytic applications such as graphene synthesis.…”

Section: Implicationmentioning

confidence: 99%

“…4a) but not the ĲMg 0.9 Fe 0.1 )O nanocondensates as prepared by the same PLA method and observed under the same TEM conditions. 41 In this connection, it is of interest to note that nanocrystalline Co/MgO has been used to catalyze the formation of carbon nanotubes from various hydrocarbons. [42][43][44] The ĲCo x Mg 1−x )O protoxide nanocondensates, especially the C1M9 and C5M5 specimens, were also found to catalyze the carbonaceous support to form a turbostratic graphene shell upon radiant heating in the present PLA process.…”

Section: Implicationmentioning

confidence: 99%