Thermally Induced Growth of ZnO Nanocrystals on Mixed Metal Oxide Surfaces

Inayat, Alexandra; Makky, Ayman; Giraldo, Jose; Kuhnt, Andreas; Busse, Corinna; Schwieger, Wilhelm

doi:10.1002/chem.201304484

Cited by 6 publications

(4 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A simple route to engineer surface texture is the growth of oxides on metal substrates. Thermal treatment of metal substrates provides a straightforward and tunable method to grow oxides. − Nonetheless, the inherently high stiffness and differences in thermal expansivities pose significant challenges in surface modification. Liquid metals, however, provide an alternative because they form nanoscale oxide shells that, because of size effects, are compliant to stresses. ,− Eutectic gallium–indium (EGaIn: 75.5% Ga, 24.5% In w/w; mp ≈ 15.7 °C) has recently found applications in soft and stretchable electronics, ,,− functional microparticles, ,,,− molecular electronics, − and functional devices. ,− EGaIn bears a thin (∼0.7–3 nm) passivating film of predominantly Ga 2 O 3 on the surface, rendering the liquid metal non-Newtonian as described above. ,,,,, The EGaIn passivating oxide layer has a graded oxide structure with the surface being primarily Ga 2 O 3 , with underlying layer(s) of Ga and In suboxides, beneath which segregated In metal has been observed. ,− This complex structure spontaneously forms to a thickness of ca.…”

Section: Introductionmentioning

confidence: 99%

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

et al. 2018

View full text Add to dashboard Cite

Droplets capture an environment-dictated equilibrium state of a liquid material. Equilibrium, however, often necessitates nanoscale interface organization, especially with formation of a passivating layer. Herein, we demonstrate that this kinetics-driven organization may predispose a material to autonomous thermal-oxidative composition inversion (TOCI) and texture reconfiguration under felicitous choice of trigger. We exploit inherent structural complexity, differential reactivity, and metastability of the ultrathin (∼0.7-3 nm) passivating oxide layer on eutectic gallium-indium (EGaIn, 75.5% Ga, 24.5% In w/w) core-shell particles to illustrate this approach to surface engineering. Two tiers of texture can be produced after ca. 15 min of heating, with the first evolution showing crumpling, while the second is a particulate growth above the first uniform texture. The formation of tier 1 texture occurs primarily because of diffusion-driven oxide buildup, which, as expected, increases stiffness of the oxide layer. The surface of this tier is rich in Ga, akin to the ambient formed passivating oxide. Tier 2 occurs at higher temperature because of thermally triggered fracture of the now thick and stiff oxide shell. This process leads to inversion in composition of the surface oxide due to higher In content on the tier 2 features. At higher temperatures (≥800 °C), significant changes in composition lead to solidification of the remaining material. Volume change upon oxidation and solidification leads to a hollow structure with a textured surface and faceted core. Controlled thermal treatment of liquid EGaIn therefore leads to tunable surface roughness, composition inversion, increased stiffness in the oxide shell, or a porous solid structure. We infer that this tunability is due to the structure of the passivating oxide layer that is driven by differences in reactivity of Ga and In and requisite enrichment of the less reactive component at the metal-oxide interface.

show abstract

Section: Introductionmentioning

confidence: 99%

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Investigations of LDHs containing Zn, Ni, Fe and Cr with carbonate as the interlayer anion showed that the decomposition stages found for the Mg/Al system are also valid for other metal combinations, while the deviance of the respective temperature ranges amounts to 50 to 100 °C for some LDH species. 194,197,198 Also the type of interlayer anion has an effect on the structural transformation of LDHs upon thermal treatment, which was shown for Zn/Al LDHs containing different interlayer anions. 198,199 Furthermore, it is noteworthy that many LDH variants exhibit the special feature called the "memory effect", i.e.…”

Section: Thermal Stability Of Ldhs and Conversion Into Mixed Metal Ox...mentioning

confidence: 89%

“…194,197,198 Also the type of interlayer anion has an effect on the structural transformation of LDHs upon thermal treatment, which was shown for Zn/Al LDHs containing different interlayer anions. 198,199 Furthermore, it is noteworthy that many LDH variants exhibit the special feature called the "memory effect", i.e. after thermal treatment up to a certain temperature (usually 200 to 500 °C) it is possible to re-establish the LDH structure through exposure to water steam or aqueous solutions of certain lost or desired interlayer anions.…”

Section: Thermal Stability Of Ldhs and Conversion Into Mixed Metal Ox...mentioning

confidence: 89%

Reactivity and applications of layered silicates and layered double hydroxides

2014

Self Cite

View full text Add to dashboard Cite

Layered materials, such as layered sodium silicates and layered double hydroxides (LDHs), are well-known for their remarkable adsorption, intercalation and swelling properties. Their tunable interlayers offer an interesting avenue for the fabrication of pillared nanoporous materials, organic-inorganic hybrid materials and catalysts or catalyst supports. This perspective article provides a summary of the reactivity and applications of layered materials including aluminium-free layered sodium silicates (kanemite, ilerite (RUB-18 or octosilicate) and magadiite) and layered double hydroxides (LDHs). Recent developments in the use of layered sodium silicates as precursors for the preparation of various porous, functional and catalytic materials including zeolites, mesoporous materials, pillared layered silicates, organic-inorganic nanocomposites and synthesis of highly dispersed nanoparticles supported on silica are reviewed in detail. Along this perspective, we have attempted to illustrate the reactivity and transformational potential of LDHs in order to deduce the main differences and similarities between these two types of layered materials.

show abstract

“…Although multiple methods are available to grow oxides, thermal treatment is still a straightforward and effective method to achieve the same. 65,66,68,137,138 Thermal oxidation not only provides characteristic texture but also renders texture tunability by varying temperature.…”

Section: Current Research On Liquid Metals and Alloysmentioning

confidence: 99%

Tuning surface texture of liquid metal particles by exploiting material metastability

Cutinho

View full text Add to dashboard Cite

Surface roughness, and associated changes in properties, often dictate how a material is utilized or manifests unprecedented capabilities to well-known materials. Most approaches to engineer surface texture are, however, predominantly based on additive and/or subtractive routes that are often either; i) inefficient (arduous, lengthy and expensive), or ii) inaccessible (due to a need for specialized equipment and skilled manpower). Understanding a materials interface structure at the sub-nanometer scale, and pairing this with its thermodynamic landscape, offers a new frugal approach to engineer its surface texture. Herein, we demonstrate thermal-driven evolution of surface morphology by exploiting inherent structural complexity, and metastability, of the ultra-thin passivating oxide on liquid metal particles. We achieve tunable surface texture via thermal-triggered oxidation of the liquid, whereby structural order on the surface was controlled through kinetics (reduction potentials of constituent elements) and stoichiometry, the latter being driven by interfacial phase-segregation upon oxidation. Release of the underlying phasesegregated components lead to inversion in the composition of the surface of these metal oxides, with concomitant growth in the thickness of the passivating layer. We divide our study in two parts viz; i) utilizing a thermodynamically stable core with a metastable shell, and ii) engineering liquid metal particles with metastable core and a metastable interface. For the former case, we obtained particles characterized by crumples, patches and multi-tiered roughness with increase in processing temperature and time. The overall structure of the particle evolves from a smooth sphere into a crumpled sphere and eventually a textured surface with increasing temperature while retaining the liquid core. At temperatures >1173 K, the liquid core is not observed but a hollow solid particle is formed with significant inter-particle sintering. For particles with metastable core vi and metastable interfaces, we observed greater effects of thermal stress due to phase change. The particles undergo spinodal decomposition upon solidification while differences in thermal expansivities of the constituent elements led to dendritic growth, albeit after a specific trigger temperature.

show abstract

Thermally Induced Growth of ZnO Nanocrystals on Mixed Metal Oxide Surfaces

Cited by 6 publications

References 22 publications

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

Reactivity and applications of layered silicates and layered double hydroxides

Tuning surface texture of liquid metal particles by exploiting material metastability

Contact Info

Product

Resources

About