Multilayer Microstructures Research Articles

Crystal Plasticity Modeling of the Effects of Crystal Orientation and Grain-to-Grain Interactions on DSA-Induced Strain Localization in Al-Li Alloys

We develop a crystal plasticity model to investigate the coupled actions of crystal orientation, grain neighborhood and grain-to-grain elasto-plastic interactions on dynamic strain aging and the onset and development of associated plastic strain localization in Al-Li alloys. Considering simple model multilayered microstructures with preferred orientations representative of rolled alloys, the aim is to identify grain orientation couples that can limit dynamic strain aging induced strain localization without compromising the flow stress and strain hardeningproperties. To this end, a slip system-based formulation of dynamic strain aging is implemented in a crystal plasticity finite element framework. The model validity is first checked with the simulation of a tensile specimen loaded at quasi-static applied strain rate. The introduction of dynamic strain aging allows predicting complex propagation of intense plastic localization bands. We further investigate the influence of crystal orientations on early strainlocalization in Al-Cu-Li-Mg alloys, by performing simulations representative of the early stage of a Kahn Tear test for single crystals and layered polycrystals. Using experimentally reported crystal orientations for rolled microstructures, the simulation results show that in both single and multilayered crystals, there is a strong influence of dynamic strain aging on localization patterns, as well as a significant orientation dependence. In multilayered crystals, the nature of strain localization can be remarkably modified when stand-alone crystals of a certain orientation are coupled with other orientations: strain localization may intensify or fades away depending on the coupling with neighboring orientations.

Overcoming diffusion limitations in supercapacitors using layered electrodes

The impact of multi-layered electrode microstructures on the dynamic capacitance of electrochemical double layer supercapacitors is investigated. An electrochemical model that describes ion diffusion and double layer dynamics across the layered electrodes is first developed and then matched to experimental data. With TiO2 particulate and carbon nanotube layered electrodes, two knee frequencies were observed in the real and imaginary capacitance plots in both experiment and model simulations. These two knee frequencies resulted in an increase in real capacitance at high frequencies (ω≈100−102 rad s−1) but a reduction at lower frequencies (ω≈10−2 rad s−1), with the response being largely insensitive to the relative layer thicknesses. The increased capacity at high frequencies was due to increased ion mobility across the electrodes caused by the layering, allowing diffusion limitations of identical homogeneous electrodes to be overcome. These results imply the suitability of layered electrodes for applications with highly dynamic charge profiles and/or relatively thick electrodes.

Reflection and transmission of elastic waves in the multilayered orthotropic couple-stressed plates sandwiched between two elastic half-spaces

• A solving method that is suitable for the wave reflection and transmission of anisotropic microstructures is presented. • Anisotropic multilayered couple-stressed plates between two elastic half-spaces are studied. • The incident P wave is influenced by one length scale parameter but the SH wave is influenced by two length scale parameters. • The length scale parameter lx has much more significant influence on SH waves than the length scale parameter ly . In this paper, a high efficient computational approach, the extended Legendre orthogonal polynomial method (LOPM) is provided to investigate the reflection and transmission of elastic waves in orthotropic couple-stress layered plates sandwiched between two elastic half-spaces. In this approach, the anisotropic couple-stress theory is introduced into the LOPM to calculate the reflection and transmission coefficients of the orthotropic interlayers. The stress components, couple-stress components, rotation vectors and governing equations are derived in terms of the Legendre orthogonal polynomial. The present method does not require calculations of the displacement solutions of each partial wave in anisotropic multilayered microstructures, but expands the displacement vector of each layer into a Legendre orthogonal polynomial series with the expansion coefficients to be calculated. The incident P wave and SH wave are calculated, respectively. The effects of length scale parameters in three different directions are studied. It is found that the reflection and transmission coefficients of the incident P wave are only related to the length scale parameter in the z direction. For incident SH wave, the influence of the length scale parameter along the thickness direction is much more significant than that of the length scale parameter in the y direction.

Microfabrication and Characterization of High Tensile Strength SiC Whisker-Reinforced Nickel Composite Coatings by Electrodeposition

Metal matrix composite materials with SiC whiskers are considered as the reinforcement materials for the future electronic devices. However, today, these materials are mostly produced at high temperature and high pressure (HTHP) environments, these procedures are not only costly but may also alter the microstructure. In order to explore an economically more viable approach of fabrication of multilayer movable complicated microstructures, SiC whiskers-reinforced nickel matrix composites (Ni/SiCw) coatings were prepared by electrolytic co-deposition method. The surface morphology and mechanical properties of the electrodeposited coatings, fabricated in both absence and presence of SiC whisker, were studied. Morphology studies showed a homogenous presence of the whisker intercalated at the surface of the nickel matrix; this was further confirmed from the results of XPS and TEM, which also demonstrated that the insertion of the whisker went from the surface to inside. Moreover, it was found that the embedded whiskers significantly affect mechanical properties of the composite coatings: the ultimate tensile strength of Ni/SiCw composite was 2.6 times higher than that of pure Ni, and the elastic modulus improved by 42% with 0.8 g/L of SiC whiskers in the bath. These results reveal the promising potential of electrodeposited metal-SiC whiskers composite materials for micro-mechanical devices application.

Fast Calculation of Scattering in Planar Uniaxial Anisotropic Multilayers

In this paper, the generalized recursive formulations of the finite difference time domain (FDTD) for updating the electric and magnetic fields in the multi-layer anisotropic media are derived with a uniaxial perfectly matched layer. The stability condition of the proposed method is clearly analyzed and verified. Then this method is used to calculate the three-dimensional complex scattering fields in planar multilayered anisotropic microstructures with optical axis perpendicular to the layered interface and the scattering fields of arbitrary shape scatters in the anisotropic layered structures. The electric field induced by the sine dipole source is calculated in the spatial domain and the corresponding spectral domain results are achieved through Fourier transform. The scattering field of composite materials with submillimeter thicknesses used in the industrial engineering is calculated using a terahertz wave with operation frequency of 0.3 THz. Robustness of the derived formulations for the complex uniaxial anisotropic media is verified by comparing with the COMSOL software, which is based on FEM analysis. The comparison of memory and CPU time shows the efficiency of the proposed FDTD method. Finally, the scattering fields of different scatters buried in multilayer anisotropic media are studied. So it is expected to become an effective simulation tool for dealing with complex electromagnetic environment in the future, such as abnormal detection of aircraft coating materials and detection of hidden target and so on.

Correlations between dislocation density evolution and spall strengths of Cu/Ta multilayered systems at the atomic scales: The role of spacing of KS interfaces

The deformation and failure (spallation) behavior of Cu/Ta multilayered systems with Kurdjumov–Sachs (KS) orientation relationship is investigated at the atomic scales under shock loading conditions. Molecular dynamics (MD) simulations investigate the role of spacing between KS interfaces on the nucleation, evolution and interaction of defect structures (dislocations) in the Cu/Ta multilayered microstructures with layer thicknesses ranging from 3 nm to 47 nm. The shock compression response and failure response is investigated using the computed values of the Hugoniot elastic limit (HEL) and the spall strengths, respectively. KS interfaces serve as strong barriers to dislocation propagation and transmission across the interface and the spacing of the interfaces is observed to influence the spall behavior. The variation of the spall strength values suggests a critical interface spacing of 6 nm, below which the spall strength of the multilayered microstructure is observed to be lower than that for single-crystal Cu for the same loading conditions. The correlations between the temporal evolution of densities of various types of dislocation at the spall planes for the various microstructures and the resulting values of the spall strengths provide a clear rationale for why a microstructure results in increased/decreased spall strength values for the multiphase system.

Design of multi-layer materials using inverse homogenization and a level set method

This work is concerned with the micro-architecture of multi-layer material that globally exhibits desired mechanical properties, for instance a negative apparent Poisson’s ratio. We use inverse homogenization, the level set method, and the shape derivative in the sense of Hadamard to identify material regions and track boundary changes within the context of the smoothed interface. The level set method and the shape derivative obtained in the smoothed interface context allows to capture, within the unit cell, the optimal micro-geometry. We test the algorithm by computing several multi-layer auxetic micro-structures. The multi-layer approach has the added benefit that contact during movement of adjacent “branches” of the micro-structure can be avoided in order to increase its capacity to withstand larger stresses.

Rational Construction of Ti3C2T x/Co-MOF-Derived Laminated Co/TiO2-C Hybrids for Enhanced Electromagnetic Wave Absorption.

Lightweight and compatible metal-organic framework (MOF)-derived carbon-based composites are widely used in electromagnetic (EM) absorption. Their combination with laminated TiO2-C (derived from Ti3C2T x) is expected to further strengthen the EM attenuation ability. Herein, novel laminated Co/TiO2-C hybrids were derived from Ti3C2T x/Co-MOF using heat treatment. Compared with pristine MOF-derived carbon-based composites, the EM absorption ability of Co/TiO2-C was improved by multiple reflections between multilayered microstructures and the improved polarization loss (due to the heterogeneous interfaces, residual defects, and dipole polarization) and the strengthened conductivity loss caused by the carbon layers. Specifically, for the Co/TiO2-C hybrids at thicknesses of 3.0 and 2.0 mm, the optimal reflection loss (RL) was -41.1 dB at 9.0 GHz and -31.0 dB at 13.9 GHz, with effective bandwidths (RL ≤ -10 dB) of 3.04 and 4.04 GHz, respectively. This study will underline the preparation of carbon-based absorbing materials starting from MXene/MOF hybrids.

Effect of annealing temperature on the corrosion resistance of MgO coatings on Mg alloy

MgO coatings were electrodeposited on Mg alloy substrates via cathodic electrolytic technique and annealed at different temperatures. The protective performance of these annealed coatings was investigated, and a correlation drawn between annealing temperature of coatings and their corrosion resistances as well as mechanical hardness. At optimum temperature (250 °C), the thermal treatment relieved internal tensile stress leading to crystallization of oxide coating layers with compact and continuous multilayered microstructures. At higher temperatures (around 500 °C), phase transformations within the coating microstructure broadened inherent inter-diffusion pathways/microdefects. Surface and bulk evidences of pores and cracks are observed at 500 °C as clear evidences of the consequence of over-calcination using scanning electron microscopy. Enhanced corrosion resistance for coatings are achieved at optimum curing temperature judging from electrochemical corrosion results after chloride-induced corrosion tests. The dependence of corrosion resistance on annealing temperature of coatings has also been investigated by potentiodynamic polarization and electrochemical impedance spectroscopic techniques. A modelled curing mechanism, as it relates to barrier performance at low and high thermal conditions, has been illustrated from experimental evidences.

A dry film technology for the manufacturing of 3-D multi-layered microstructures and buried channels for lab-on-chip

The development of innovative and reliable techniques for devices miniaturization are enabling the massive growth of lab on chip (LOC) applications. In this article, we briefly review the technological options for LOC microfabrication, then we present the optimization of a process for the realization of tridimensional multi-layered structures and buried channels in a microfluidic network using a photo-patternable dry film, with a potential for LOC manufacturing. The tuning of all the fabrication parameters is widely discussed and micrographs and optical profiler images are reported to show fabrication results. The fabrication process is used for a Split-flow-thin (SPLITT) fractionation cell configuration. SPLITT is a particle fractionation technique based on the combined effect of two laminar streams (the sample containing the particles and a carrier) flowing inside a thin microchannel and the action of a vertical driving force for particle displacement. Since the SPLITT implemented in this work is electrically driven, patterned electrodes (thickness: 100 nm) are also integrated in the flow cell walls. The functionality of the cell was tested first verifying the presence of proper flow conditions for microfluidic SPLITT (absence of mixing between the streams) and then proving electrical fractionation with two different proteins (BSA and β-lactoglobulin) at different levels of ionic strength. The flow of the streams within the microfluidic channel was also simulated by a numerical 2-D model exactly reproducing the cell geometry, with a good accordance with experimental results.

Synthesis of ZnO particles with multi-layer and biomorphic porous microstructures and ZnO/rGO composites and their applications for photocatalysis

Novel ZnO particles with hierarchical and biomorphic porous microstructures were first synthesized through a bionic method and the individual ZnO, pine cones-like ZnO/rGO composites were prepared via ‘one-pot’ solvothermal route. All of above samples are characterized by SEM, XRD, Raman spectrometer and XPS. The results of degradation of rhodamine B indicated that ZnO/leaf exhibited better photocatalytic properties than individual ZnO, the ZnO/rGO with ZnO/rGO ratios at 20:1 shows the best photocatalytic performance. Results indicate that both the morphology design of ZnO through a bionic method and graphene doping can enhance the photocatalytic performance of zinc oxide.

Engineering polymer MEMS using combined microfluidic pervaporation and micro-molding

In view of the extensive increase of flexible devices and wearable electronics, the development of polymer micro-electro-mechanical systems (MEMS) is becoming more and more important since their potential to meet the multiple needs for sensing applications in flexible electronics is now clearly established. Nevertheless, polymer micromachining for MEMS applications is not yet as mature as its silicon counterpart, and innovative microfabrication techniques are still expected. We show in the present work an emerging and versatile microfabrication method to produce arbitrary organic, spatially resolved multilayer micro-structures, starting from dilute inks, and with possibly a large choice of materials. This approach consists in extending classical microfluidic pervaporation combined with MIcro-Molding In Capillaries. To illustrate the potential of this technique, bilayer polymer double-clamped resonators with integrated piezoresistive readout have been fabricated, characterized, and applied to humidity sensing. The present work opens new opportunities for the conception and integration of polymers in MEMS.

Experimental research on eliminating the stair-stepping effect of laminated 3D microelectrodes by micro-ECM

With three-dimensional (3D) microelectrodes used to machine microcavities in microelectrical discharge machining (micro-EDM), the processing efficiency can be greatly improved. However, the surfaces of a laminated 3D microelectrode always have stair steps, which will be further copied to the machined surfaces of the microcavities, reducing the processed surface quality. To solve the problems, the paper proposed using layer-by-layer scanning microelectrochemical machining (micro-ECM) to eliminate the stair-stepping effect of the laminated 3D microelectrodes. First, wire electrical discharge machining (WEDM) was chosen to cut Cu foils for obtaining multilayer two-dimensional (2D) microstructures. Second, the multilayer 2D microstructures were applied to thermal diffusion bonding to form 3D microelectrode blanks. Then, the 3D microelectrode blanks were processed via layer-by-layer scanning micro-ECM to eliminate the stair steps on the surfaces. The influences of applied voltage, offset distance, and layer thickness on the elimination of the stair-stepping effect were investigated in details. Experimental results show that the stair steps on the laminated 3D microelectrode surfaces were eliminated obviously under 4.0 V applied voltage, 200 μm offset distance, and 20 μm layer thickness. Finally, the laminated 3D microelectrodes without stair steps on the surfaces were applied to micro-EDM to process microcavities. Two typical microcavities without the stair steps were obtained.

Multispectral selective near-perfect light absorption by graphene monolayer using aperiodic multilayer microstructures

We investigate one-dimensional aperiodic multilayer microstructures in order to achieve near-total absorptions at preselected wavelengths in a graphene monolayer. The proposed structures are designed using a genetic optimization algorithm coupled to a transfer matrix code. Coupled-mode-theory analysis, consistent with transfer matrix method results, indicates the existence of a critical coupling in the graphene monolayer for perfect absorptions. Our findings show that the near-total-absorption peaks are highly tunable and can be controlled simultaneously or independently in a wide range of wavelengths in the near-infrared and visible ranges. The proposed approach is metal-free, does not require surface texturing or patterning, and can be also applied for other two-dimensional materials.

Elimination of 3D micro-electrode’s step effect and applying it in micro-EDM

3D micro-electrode is fitted out by multilayer 2D micro-structures, so the steps inevitably occur in the 3D micro-electrode. When the 3D micro-electrode is used in micro-EDM, steps are replicated onto the surface of the 3D micro-structure, which have an adverse impact on the shape precision of the 3D micro-structure. Focus on this problem, this paper proposed to eliminate the steps of the 3D micro-electrode based on skin effect and point discharge. Then, the paper detailedly researched the impact of machining voltage, machining depth, and processing numbers on the elimination of 3D micro-electrode’s step effect and its micro-EDM results. In order to verify the feasibility of this method, the paper designed a 3D micro-cavity structure which has slopes in the X and Y directions with slope angle of 45°. Finally, under workpiece of 304# stainless steel, pulse width of 800 ns, pulse interval of 4200 ns, machining voltage of 110 V, and machining depth of 650 μm (250 μm larger than the design depth), the step effect of the 3D micro-electrode was effectively eliminated and its micro-EDM result has a dimension error within 7 μm and slope error within 3°.

Nature and Functionality of La0.58Sr0.4Co0.2Fe0.8O3-δ / Gd0.2Ce0.8O2-δ / Y0.16Zr0.84O2-δ Interfaces in SOFCs

Interdiffusion phenomena and secondary phase formation at the interface La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF) / Gd0.2Ce0.8O2-δ (GDC) / Y0.16Zr0.84O2-δ (YSZ) are correlated to linear and non-linear losses in symmetrical and full SOFC cells. FIB/SEM (focussed ion beam / scanning electron microscopy) tomography is applied for determining the local distribution of the primary phases LSCF, GDC, and YSZ and elemental analysis via STEM/EDXS (scanning transmission electron microscopy / energy dispersive X-ray spectroscopy) provides information on the secondary phase SrZrO3 (SZO) and the interdiffusion between GDC and YSZ (ID). This reveals the effect of GDC co-sintering temperature (varied from 1100°C to 1400°C), alongside the sintering of LSCF at 1080°C, on these multi-layered microstructures. Electrochemical impedance spectra on symmetrical cells show that the polarization resistance (ASRcat) of the cathode/electrolyte interface is pronouncedly affected by three orders of magnitude, changing the overall power density of anode supported SOFC single cells at 0.8V by as much as a factor of 20. In conclusion, the chemical composition of the ID has a tremendous impact on the electrochemical efficiency of the investigated LSCF/GDC/YSZ interface, and processing parameters of anode supported cells with LSCF cathode have to be carefully chosen for individual SOFC cell concepts.

Effects of carbon nanotubes by electrophoretic deposition on interlaminar properties of two dimensional carbon/carbon composites

Carbon nanotubes (CNTs) were deposited uniformly on carbon cloth by electrophoretic deposition (EPD). Thereafter, CNT-doped clothes were stacked and densified by pyrocarbon via chemical vapor infiltration to fabricate two-dimensional (2D) carbon/carbon (C/C) composites. Effects of EPD CNTs on interlaminar shear performance and mode II interlaminar fracture toughness (G IIc) of 2D C/C composites were investigated. Results showed that EPD CNTs were uniformly covered on carbon fibers, acting as a porous coating. Such a CNT coating can obviously enhance the interlaminar shear strength and G IIc of 2D C/C composites. With increaing EPD CNTs, the interlaminar shear strength and G IIc of 2D C/C composites increase greatly and then decrease, both of which run up to their maximum values, i e, 13.6 MPa and 436.0 J·m−2, when the content of EPD CNTs is 0.54 wt%, 2.27 and 1.45 times of the baseline. Such improvements in interlaminar performance of 2D C/C composites are mainly beneficial from their increased cohesion of interlaminar matrix, which is caused not only by the direct reinforcing effect of EPD CNT network but also by the capacity of EPD CNTs to refine pyrocarbon matrix and induce multilayered microstructures that greatly increase the crack propagation resistance through “crack-blocking and -deflecting mechanisms”.

Scaling behavior of nanoimprint and nanoprinting lithography for producing nanostructures of molybdenum disulfide

Top-down lithography techniques are needed for manufacturing uniform device structures based on emerging 2D-layered materials. Mechanical exfoliation approaches based on nanoimprint and nanoprint principles are capable of producing ordered arrays of multilayer transition metal dichalcogenide microstructures with a high uniformity of feature dimensions. In this study, we present a study on the applicability of nanoimprint-assisted shear exfoliation for generating ultrathin monolayer and few-layer MoS2 structures as well as the critical limits of feature dimensions produced via such nanoimprint and nanoprint-based processes. In particular, this work shows that give a lateral feature size of MoS2 structures that are pre-patterned on a bulk stamp, there exists a critical thickness or aspect ratio value, below which the exfoliated layered structures exhibit major defects. To exfoliate a high-quality, uniform monolayer or few-layer structures, the characteristic lateral feature sizes of such structures need to be in the sub-100 nm regimes. In addition, the exfoliated MoS2 flakes of critical thicknesses exhibit prominent interlayer twisting features on their cleaved surfaces. Field-effect transistors made from these MoS2 flakes exhibit multiple (or quasi-analog-tunable) charge memory states. This work advances the knowledge regarding the limitations and application scope of nanoimprint and nanoprint processes in manufacturing nano/microstructures based on layered materials and provides a method for producing multi-bit charge memory devices.

Structure-Performance Relations in Multi-Layer Solid-State Li-Ion Electrolytes Using FIB-Tomography

As demands on battery technology approach the limits of standard organic liquid electrolytes, a multitude of new materials are being developed as potential replacements, including solid-state Li-conducting ceramics. However, the major obstacles to integrating solid electrolytes into Li-ion batteries originate primarily from the relatively low ionic conductivity of the electrolyte itself (compared to organic liquid electrolytes) and from the high interfacial impedance associated with poor electrolyte-electrode contact. Several solid electrolytes, including the garnet-like ceramic Li7La3Zr2O12 (LLZ), have partially addressed the first issue by achieving ionic conductivities of ~1 mS/cm, approaching that of organic liquid electrolytes. With regards to high interfacial impedance, surface chemistry modifications at the electrolyte-electrode interface have greatly improved solid-solid contact with lithium metal anodes, though cathode interfaces remain a significant challenge for solid-state batteries. An especially promising development replaces the typical pellet geometry with a variable-porosity multi-layer structure, resulting in dramatically increased electrolyte-electrode interfacial area, thus decreasing interfacial impedance. Such an approach opens the possibility of tailoring the architecture of the electrolyte microstructure to improve the electrolyte-electrode interface and all-solid battery performance. However, what constitutes the ideal microstructure is currently unknown. At the same time, adopting such a complex structure may introduce unforeseen effects that impact overall electrolyte properties, positively or negatively. Li-ion migration through tortuous electrolyte pathways, cycling of electrode material at varying distances from the electrolyte dense layer, and effective pore filling by the electrodes are some of the new variables that must be accounted for when designing and evaluating such structures. While research on non-planar solid electrolytes exists, the focus has been limited to thin film batteries, with little work undertaken for macro-scale systems. Here, we have varied the porosity of high dimension (>100 um thick) LLZ electrolyte porous-dense-porous multi-layers, characterized the physical microstructure of the layers, and investigated how key structural parameters (e.g., tortuosity, LLZ/pore volume fractions, MAZO angle) related to the electrochemical properties. To study the LLZ microstructure, we utilized focused ion beam (FIB) tomography to reconstruct 3D representations of regions in the electrolyte, from which structural parameters were calculated. Samples to be analyzed were epoxy infiltrated and mounted in a Xenon-plasma source FIB/SEM, where we deposited platinum on the area of interest and milled a trench around the area to expose a cross-section of the LLZ (Figure 1, top). We then moved the sample to a Gallium-ion source FIB/SEM to finish polishing the cross-section (Figure 1, bottom), followed by serial milling-and-imaging to produce the set of images necessary for 3D reconstruction. To evaluate electrolyte performance, we relied on electrochemical impedance spectroscopy (EIS) to determine Li-ion conductivities for the different LLZ multi-layer microstructures.

Peculiarity of self-assembled cubic nanolamellae in the TiN/AlN system: Epitaxial self-stabilization by element deficiency/excess

Synthesis of self-assembled thin films with multi-layered microstructures and outstanding functional properties represents a challenging task. In this work, detailed microstructural and chemical analyses of a self-assembled ∼3.8 μm thick cubic (c) (AlxTi1-x)yN1-y film grown by low pressure chemical vapour deposition on a Al2O3(0001) substrate is discussed. The film with an overall x fraction of ∼0.8 consists of alternating non-stoichiometric cubic Al-rich and Ti-rich nanolamellae with thicknesses of ∼11 and ∼1.5 nm. X-ray diffraction, electron microscopy and electron energy loss spectroscopy indicate that the nanolamellae coherency is primarily a result of an N deficiency in Ti-rich nanolamellae and an N excess in Al-rich nanolamellae, which induce a decrease and an increase in nanolamellae lattice parameters, compared to the lattice parameters of stoichiometric rock-salt c-TiN and c-AlN, respectively. Therefore the self-assembly allows a formation of c-(AlxTi1-x)yN1-y nanolamellae with Al atomic fraction x of 0.9–1.0, which are stabilized by neighbouring Ti-rich nanolamellae as a result of cube-on-cube epitaxy. The effect of the lattice parameter self-adjustment in the coherent nanolamellae by element deficiency and excess is verified by ab initio calculations. The compositional and morphological matches of the nanolamellae interfaces at the grain boundaries, the terraced growth with tetrahedral surface morphology and unzipped facets as well as the uniform nanolamellae thickness across the film depth indicate that the nanolamellae are formed as a result of kinetically-controlled oscillating reactions during the film growth. The understanding of this fascinating self-assembled nanolamellar microstructure containing a meta-stable c-AlNy, which does not exist in a bulk form at ambient conditions, represents a milestone in thin film technology.