Reactive metal–oxide interfaces: A microscopic view

Abstract

Metal-oxide interfaces play a fundamental role in determining the functional properties of artificial layered heterostructures, which are at the root of present and future technological applications. Magnetic exchange and magnetoelectric coupling, spin filtering, metal passivation, catalytic activity of oxide-supported nano-particles are just few examples of physical and chemical processes arising at metal-oxide hybrid systems, readily exploited in working devices. These phenomena are strictly correlated with the chemical and structural characteristics of the metal-oxide interfacial region, making a thorough understanding of the atomistic mechanisms responsible of its formation a prerequisite in order to tailor the device properties. The steep compositional gradient established upon formation of metal-oxide heterostructures drives strong chemical interactions at the interface, making the metal-oxide boundary region a complex system to treat, both from an experimental and a theoretical point of view. However, once properly mastered, interfacial chemical interactions offer a further degree of freedom for tuning the material properties. The goal of the present review is to provide a summary of the latest achievements in the understanding of metal/oxide and oxide/metal layered systems characterized by reactive interfaces. The influence of the interface composition on the structural, electronic and magnetic properties will be highlighted. Particular emphasis will be devoted to the discussion of ultra-thin epitaxial oxides stabilized on highly oxidizable metals, which have been rarely exploited as oxide supports as compared to the much more widespread noble and quasi noble metallic substrates. In this frame, an extensive discussion is devoted to the microscopic characterization of interfaces between epitaxial metal oxides and the Fe(001) substrate, regarded from the one hand as a prototypical ferromagnetic material and from the other hand as a highly oxidizable metal.

Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in <em>Escherichia coli</em> and M13 bacteriophage

“…4,5 Thus, the combination of UV and MO nanoparticles can be applied for a future disinfection system. [9][10][11] Adsorption function of MO nanoparticles to microorganisms can induce the disruption of bio-membranes and massive leakage of cell contents, due to their surface characteristics and physicochemical properties. 12 MO nanoparticles also have disinfection potential under UV irradiation, as well as in dark conditions.…”

“…8,28 MO nanoparticles generally have a highly crystalline structure, uniform particle shape, nanoscale size, and large surface area with mesopores for chemical and biological adsorption. 7,10 These properties were dependent on the synthesis techniques (e.g., sol-gel processing 11 and thermal evaporation 29 ) and the conditions which affect MO nanocrystal growth. 30 From the sharp peaks in PXRD patterns (Figure 2), ZnO nanoparticles showed a hexagonal Wurzite structure.…”

“…28,35,37,38 The nanocrystalline structures of MO nanoparticles ( Figure 4) were matched with PXRD and FE-SEM results. In terms of electrostatic characteristics, MO nanoparticles function as photocatalysts that lead to antimicrobial activities 10,22 based on ROS generation by the electronic curvatures in reciprocal space of the conduction band minimum and valence band maximum, and dispersions of electron-hole effective masses. 24 They have wide band gap energies (ZnO, 3.3 eV; ZnTiO 3 , 2.9 eV; MgO, 7.8 eV; CuO, 1.2 eV).…”

Combined spectroscopic and ab initio investigation of monolayer-range Cr oxides on Fe(001): The effect of ordered vacancy superstructure

“…We have recently investigated such systems, with a particular focus on the coupling with the ferromagnetic Fe(001) substrate [10,11].…”

Magnetic anisotropy at the buried CoO/Fe interface

“…[12][13][14][15][16] The preparation conditions, as well as the growth order, are of great importance to understand and control their magnetic properties. 17 In particular, the CoO/Fe(001) interface has been a workbench for many investigations related to AF/FM systems with reactive interfaces, ranging from the exchange bias mechanism, 14,18 to the influence of structure and stoichiometry on the magnetic properties, 19 to the realization of peculiar magnetic configurations, like vortices. 20 Very recently, we have demonstrated that it is possible to prepare a CoO/Fe(001) interface characterized by the absence of any Fe oxide, 21,22 which is a quite unique feature with respect to the common experimental situations.…”