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Atomic-scale characteristics of individual nanocrystals (NCs), such as the crystallographic orientation of their facets and the kind and density of crystal structure defects, play a tremendous role for the functionality and performance of the whole NC population. However, these features are usually quantified only for a small number of individual particles, and thus with limited statistical relevance. In the present work, we developed the multiscale approach available in transmission electron microscopy (TEM) further, and applied it to describe features of different types of Au NCs in a statistical and scale-bridging manner. This approach combines high-resolution TEM, which is capable of describing the characteristics of NCs on atomic scale, with a semi-automatic analysis of low-magnification high-angle annular dark-field scanning TEM images, which reveals the nanoscopic morphological attributes of NCs with good statistics. The results of these complementary techniques are combined and correlated. The potential of this multiscale approach is illustrated on two examples. In the first one, the habitus of Au NCs was classified and assigned to multiply twinned nanoparticles and nanoplates. These classes were quantified and related to different stacking fault densities. The second example demonstrates the statistical determination of crystallographic orientations and configurations of facets in Au nanorods.

Sol–gel derived hydroxyapatite coatings on metallic implants are important to promote their osseointegration and biocompatibility. However, such coatings generally suffer from drawbacks that limit implant longevity. In this study, the sol gel process to prepare hydroxyapatite was optimized and used to deposit a hydroxyapatite layer on Ti6Al4V. Samples were pretreated by thermal oxidation, sol–gel coating, and anodization to produce titanium dioxide interlayers with various structures. The results of structural and thermal analysis have determined the optimal preparation parameters to produce monophasic and crystalline hydroxyapatite. The introduction of titanium dioxide intermediate layers produced crack-free hydroxyapatite films and promoted the adherence and integrity of the coating, where the adhesive strength was remarkably improved. Furthermore, potentiodynamic polarization tests in simulated body fluid revealed low corrosion rates and high protection property of the hydroxyapatite/titania coated samples, making these structures promising for the coatings of bone replacements. Graphical abstract

Self-assembly is an attractive phenomenon that, with proper handling, can enable the production of sophisticated hybrid nanostructures with sub-nm-scale precision. The importance of this phenomenon is particularly notable in the fabrication of metal–organic nanomaterials as promising substances for spintronic devices. The exploitation of self-assembly in nanofabrication requires a comprehension of atomic processes creating hybrid nanostructures. Here, we focus on the self-assembly processes in the vapour-deposited AuxC60 mixture films, revealing the exciting quantum plasmon effects. Through a systematic characterization of the AuxC60 films carried out using structure-sensitive techniques, we have established correlations between the film nanostructure and the Au concentration, x. The analysis of these correlations designates the Au intercalation into the C60 lattice and the Au clustering as the basic processes of the nanostructure self-assembly in the mixture films, the efficiency of which strongly depends on x. The evaluation of this dependence for the AuxC60 composite nanostructures formed in a certain composition interval allows us to control the size of the Au clusters and the intercluster spacing by adjusting the Au concentration only. This study represents the self-assembled AuxC60 mixtures as quantum materials with electronic functions tuneable by the Au concentration in the depositing mixture.

The dynamic recrystallization and changes in the preferred orientation of crystallites during hot rolling at 500 °C have been studied on a cast Mg-6.8Y-2.5Zn-0.3Zr (wt. %) alloy (WZ73) containing long-period stacking ordered (LPSO) phases. The recrystallization began predominantly within twins and also occurred near the LPSO phases. The twinned regions have a much higher stored strain energy compared to the matrix, and are therefore favorable nucleation sites for dynamic recrystallization. Besides, the bits of the LPSO phase located at the grain boundaries of the magnesium matrix grains act as nucleation sites for dynamic recrystallization. With increasing strain from 36 % to 74 %, the average volume fraction of recrystallized grains increased from 3.5 % to 48.8 %. The intensive recrystallization process resulted in basal texture weakening. Thus, the resulting microstructure is a mixture of randomly oriented, dynamically recrystallized and coarse, highly oriented non-recrystallized grains.

Marine sponges were among the first multicellular organisms on our planet and have survived to this day thanks to their unique mechanisms of chemical defense and the specific design of their skeletons, which have been optimized over millions of years of evolution to effectively inhabit the aquatic environment. In this work, we carried out studies to elucidate the nature and nanostructural organization of three-dimensional skeletal microfibers of the giant marine demosponge Ianthella basta, the body of which is a micro-reticular, durable structure that determines the ideal filtration function of this organism. For the first time, using the battery of analytical tools including three-dimensional micro—X-ray Fluorescence (3D-µXRF), X-ray diffraction (XRD), infra-red (FTIR), Raman and Near Edge X-ray Fine Structure (NEXAFS) spectroscopy, we have shown that biomineral calcite is responsible for nano-tuning the skeletal fibers of this sponge species. This is the first report on the presence of a calcitic mineral phase in representatives of verongiid sponges which belong to the class Demospongiae. Our experimental data suggest a possible role for structural amino polysaccharide chitin as a template for calcification. Our study suggests further experiments to elucidate both the origin of calcium carbonate inside the skeleton of this sponge and the mechanisms of biomineralization in the surface layers of chitin microfibers saturated with bromotyrosines, which have effective antimicrobial properties and are responsible for the chemical defense of this organism. The discovery of the calcified phase in the chitinous template of I. basta skeleton is expected to broaden the knowledge in biomineralization science where the calcium carbonate is regarded as a valuable material for applications in biomedicine, environmental science, and even in civil engineering.

In recent years, nanolamellar aluminum-rich face-centered cubic (fcc) Ti1-xAlxN coatings with x as high as 0.8–0.9 grown by thermal chemical vapor deposition (CVD) have been investigated extensively. However, detailed information about their microstructure characteristics, local chemical composition and phase stability at elevated temperatures is still missing. Thus, within the present work, the temperature-induced microstructural changes of a nanolamellar fcc-Ti0.2Al0.8N coating, synthesized by thermal CVD at ∼790 °C, were studied up to temperatures of 1300 °C. In situ high-temperature X-ray powder diffraction and differential scanning calorimetry were employed to follow the phase evolution at elevated temperatures. Scanning electron microscopy and electron backscatter diffraction, carried out ex situ for six different microstructural states after isothermal annealing, revealed the distribution of individual phases and morphology of different phase regions. Complementary atom probe tomography as well as transmission electron microscopy experiments were performed on the as-deposited, an intermediate and the final decomposed and transformed state. The results provided 3D elemental information as well as detailed morphology, phase and orientation information of the respective samples. In the as-deposited state, the coating was characterized by columnar, relatively large fcc grains exhibiting a nanolamellar microstructure. Decomposition of initially supersaturated fcc-Ti1-xAlxN was detected at temperatures of ∼900–1000 °C. Transformation of metastable Al-rich fcc regions into the thermodynamically stable wurtzitic modification started at ∼1000 °C and persisted up to ∼1175 °C. In this temperature range, intact nanolamellar fcc areas coexisted with fully decomposed and transformed regions, leading to a constant reduction of the fcc fraction with increasing temperature. At temperatures above ∼1175 °C, the coating was fully decomposed and transformed into fcc-TiN and w-AlN. The obtained findings provide a detailed description of the decomposition and transformation behavior of nanolamellar CVD fcc-Ti1-xAlxN coatings, which significantly contributes to the fundamental understanding of this complex coating system.

Three types of hexagonal boron nitride (h-BN) with graphitic crystal structure having different microstructures were subjected to high pressures (HP) and high temperatures (HT), and the kinetics of the phase transitions to the sp3-hybridized phases (w-BN, c-BN) was studied using in situ synchrotron diffraction. The analysis of the phase transformation kinetics revealed the transformation paths and activation energies Ea of the transformation of h-BN to the high-pressure forms of BN for different microstructures of h-BN. Defect-poor h-BN transforms to metastable wurtzitic BN (w-BN) with Ea ≈ 0.3 eV/at. Defect-rich forms of h-BN transform directly to c-BN, but with a higher activation energy. It was observed that the turbostratic disorder in h-BN retards the phase transition as compared to h-BN containing corrugated basal planes and a low degree of turbostracity. The experimental results are discussed in view of the microstructure changes during the HP/HT treatment and compared to available theoretical phase transition models.

The defect structure of γ-Al2O3 produced from boehmite is described with the aid of antiphase and rotational boundaries. The type of structure defects is deduced from the selected-area electron-diffraction patterns. The defect density is quantified from the anisotropic broadening of diffraction lines in powder X-ray diffraction patterns using a computer routine based on the Debye scattering equation., The defect structure of γ-Al2O3 derived from boehmite was investigated using a combination of selected-area electron diffraction (SAED) and powder X-ray diffraction (XRD). Both methods confirmed a strong dependence of the diffraction line broadening on the diffraction indices known from literature. The analysis of the SAED patterns revealed that the dominant structure defects in the spinel-type γ-Al2O3 are antiphase boundaries located on the lattice planes , which produce the sublattice shifts . Quantitative information about the defect structure of γ-Al2O3 was obtained from the powder XRD patterns. This includes mainly the size of γ-Al2O3 crystallites and the density of planar defects. The correlation between the density of the planar defects and the presence of structural vacancies, which maintain the stoichiometry of the spinel-type γ-Al2O3, is discussed. A computer routine running on a fast graphical processing unit was written for simulation of the XRD patterns. This routine calculates the atomic positions for a given kind and density of planar defect, and simulates the diffracted intensities with the aid of the Debye scattering equation.

Hematite (alpha-Fe2O3) catalysts prepared using the precipitation methods was found to be highly effective, and therefore, it was studied with methane (CH4), showing an excellent stable performance below 500 degrees C. This study investigates hematite nanoparticles (NPs) obtained by precipitation in water from the precursor of ferric chloride hexahydrate using precipitating agents NaOH or NH4OH at maintained pH 11 and calcined up to 500 degrees C for the catalytic oxidation of low concentrations of CH4 (5% by volume in air) at 500 degrees C to compare their structural state in a CH4 reducing environment. The conversion (%) of CH4 values decreasing with time was discussed according to the course of different transformation of goethite and hydrohematites NPs precursors to magnetite and the structural state of the calcined hydrohematites. The phase composition, the size and morphology of nanocrystallites, thermal transformation of precipitates and the specific surface area of the NPs were characterized in detail by X-ray powder diffraction, transmission electron microscopy, infrared spectroscopy, thermal TG/DTA analysis and nitrogen physisorption measurements. The results support the finding that after goethite dehydration, transformation to hydrohematite due to structurally incorporated water and vacancies is different from hydrohematite alpha-Fe2O3. The surface area SBET of Fe2O3_NH-70 precipitate composed of protohematite was larger by about 53 m(2)/g in comparison with Fe2O3_Na-70 precipitate composed of goethite. The oxidation of methane was positively influenced by the hydrohematites of the smaller particle size and the largest lattice volume containing structurally incorporated water and vacancies. Web of Science 23 15 art. no. 8163

The design of new composite materials using extreme biomimetics is of crucial importance for bioinspired materials science. Further progress in research and application of these new materials is impossible without understanding the mechanisms of formation, as well as structural features at the molecular and nano-level. It presents a challenge to obtain a holistic understanding of the mechanisms underlying the interaction of organic and inorganic phases under conditions of harsh chemical reactions for biopolymers. Yet, an understanding of these mechanisms can lead to the development of unusual—but functional—hybrid materials. In this work, a key way of designing centimeter-scale macroporous 3D composites, using renewable marine biopolymer spongin and a model industrial solution that simulates the highly toxic copper-containing waste generated in the production of printed circuit boards worldwide, is proposed. A new spongin–atacamite composite material is developed and its structure is confirmed using neutron diffraction, X-ray diffraction, high-resolution transmission electron microscopy/selected-area electron diffraction, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and electron paramagnetic resonance spectroscopy. The formation mechanism for this material is also proposed. This study provides experimental evidence suggesting multifunctional applicability of the designed composite in the development of 3D constructed sensors, catalysts, and antibacterial filter systems.

The size fractionation of magnetic nanoparticles is a technical problem, which until today can only be solved with great effort. Nevertheless, there is an important demand for nanoparticles with sharp size distributions, for example for medical technology or sensor technology. Using magnetic chromatography, we show a promising method for fractionation of magnetic nanoparticles with respect to their size and/or magnetic properties. This was achieved by passing magnetic nanoparticles through a packed bed of fine steel spheres with which they interact magnetically because single domain ferro-/ferrimagnetic nanoparticles show a spontaneous magnetization. Since the strength of this interaction is related to particle size, the principle is suitable for size fractionation. This concept was transferred into a continuous process in this work using a so-called simulated moving bed chromatography. Applying a suspension of magnetic nanoparticles within a size range from 20 to 120 nm, the process showed a separation sharpness of up to 0.52 with recovery rates of 100%. The continuous feed stream of magnetic nanoparticles could be fractionated with a space-time-yield of up to 5 mg/(L∙min). Due to the easy scalability of continuous chromatography, the process is a promising approach for the efficient fractionation of industrially relevant amounts of magnetic nanoparticles.

Materials characterization 176(111132), 1-14 (2021). doi:10.1016/j.matchar.2021.111132, The interplay of microstructural mechanisms controlling the deformation-induced martensitic phase transformationsand the texture formation in all phases of a metastable austenitic Cr-Mn-Ni steel was investigatedusing in situ synchrotron radiation diffraction under uniaxial compression and ex situ electron backscatterdiffraction. With increasing deformation, the originally fully austenitic steel transformed to a mixture ofγ-austenite, ε-martensite and α´-martensite. The face centred cubic γ-austenite formed a fibre texture {110} withrespect to the deformation direction. The texture degree increased progressively with increasing deformation.The hexagonal close packed ε-martensite was preferentially oriented with the reciprocal direction {1013} alongthe load axis. The texture degree was nearly independent of the deformation extent. The body centredα´-martensite formed a mixed texture {100} & {111} along the deformation direction. The texture component{100} was very strong in the early stages of the α´-martensite formation, but it deteriorated with increasingdeformation. The texture evolution is explained by the competition between the transformation texture, severaldeformation-induced mechanisms, which are highly sensitive to the local orientation of the grains with respect tothe acting force, like the stacking fault formation and martensitic transformation in austenite, and the variantselection in both martensites and the twinning of α´-martensite., Published by Science Direct, New York, NY

Selected hypermineralized bones (rostrum and tympanic bullae) have yet to be characterized for diverse species of whales (Cetacea). Hypermineralization in these structures is an example of extreme biomineralization that, however, occurs at temperatures around 36 °C. In this study we present the results of analytical investigations of the specimen of tympanic bulla isolated from gray whale (Eschrichtius robustus) for the first time. Examination of the internal surface of the bone mechanically crushed under a press revealed the presence of a lipid-containing phase, which did not disappear even after complete demineralization of the bone material. Additionally, analytical investigations including CARS, ATR-FTIR, Raman and XRD confirmed the presence of carbonated bioapatite and a collagen- lipid complex as the main components of this up to 2.34 kg/cm3 dense bone. Our experimental results open the way for further research on understanding of the principles of hypermineralization in highly specialized whale bones.

Chitin, as one of nature&rsquo, s most abundant structural polysaccharides, possesses worldwide, high industrial potential and a functionality that is topically pertinent. Nowadays, the metallization of naturally predesigned, 3D chitinous scaffolds originating from marine sponges is drawing focused attention. These invertebrates represent a unique, renewable source of specialized chitin due to their ability to grow under marine farming conditions. In this study, the development of composite material in the form of 3D chitin-based skeletal scaffolds covered with silver nanoparticles (AgNPs) and Ag-bromide is described for the first time. Additionally, the antibacterial properties of the obtained materials and their possible applications as a water filtration system are also investigated.

Structure-based tissue engineering requires large-scale 3D cell/tissue manufacture technologies, to produce biologically active scaffolds. Special attention is currently paid to naturally pre-designed scaffolds found in skeletons of marine sponges, which represent a renewable resource of biomaterials. Here, an innovative approach to the production of mineralized scaffolds of natural origin is proposed. For the first time, a method to obtain calcium carbonate deposition ex vivo, using living mollusks hemolymph and a marine-sponge-derived template, is specifically described. For this purpose, the marine sponge Aplysin aarcheri and the terrestrial snail Cornu aspersum were selected as appropriate 3D chitinous scaffold and as hemolymph donor, respectively. The formation of calcium-based phase on the surface of chitinous matrix after its immersion into hemolymph was confirmed by Alizarin Red staining. A direct role of mollusks hemocytes is proposed in the creation of fine-tuned microenvironment necessary for calcification ex vivo. The X-ray diffraction pattern of the sample showed a high CaCO3 amorphous content. Raman spectroscopy evidenced also a crystalline component, with spectra corresponding to biogenic calcite. This study resulted in the development of a new biomimetic product based on ex vivo synthetized ACC and calcite tightly bound to the surface of 3D sponge chitin structure. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Naturalis Biodiversity Center Ministerio de Ciencia, Tecnología y Medio Ambiente, CITMA: 18-54-34007 Deutsche Forschungsgemeinschaft, DFG: HE 394/3 Russian Foundation for Basic Research, RFBR Russian Science Foundation, RSF: 18-13-00220 57397326 Ministerstwo Nauki i Szkolnictwa Wyższego, MNiSW: 03/32/SBAD/0906 PPN/BEK/2018/1/00071 Deutscher Akademischer Austauschdienst, DAAD Sächsisches Staatsministerium für Wissenschaft und Kunst, SMWK: 02010311 Funding: This work was partially supported by the DFG Project HE 394/3, SMWK Project no. 02010311 (Germany), as well as DAAD-Italy Project “Marine Sponges as Sources for Bioinspired Materials Science” (No. 57397326). The sampling conducted in Cuba (V.I.) and Curaçao (V.I. and B.H.) was funded by RFBR and CITMA, according to the research project 18-54-34007 (grant), and Temminck-Fellowships from the Naturalis Biodiversity Center, respectively. M.W is financially supported by the Polish National Agency for Academic Exchange (PPN/BEK/2018/1/00071). Tomasz Machałowski is supported by DAAD (Personal ref. no. 91734605). Yuliya Khrunyk is supported by the Russian Science Foundation (grant no. 18-13-00220). This research was partially funded by the Ministry of Science and Higher Education (Poland), as financial subsidy to PUT No. 03/32/SBAD/0906.

Although the concept of quantum confinement was introduced more than thirty years ago, a wide application of quantum dots is still limited by the fact that monodisperse quantum dots with controlled optoelectronic properties are typically synthesized on a relatively small scale. Larger scale synthesis techniques are usually not able to produce monodisperse nanoparticles yet. In this contribution, we illustrate the capability of the combination of transmission electron microscopy and X-ray diffraction to reveal detailed and scale-bridging information about the complex microstructure of non-monodisperse quantum dots, which is the first step towards further upscaling of the techniques for production of quantum dots with controlled properties. As a model system, CdSe quantum dots synthesized using an automated robotic hot-injection method at different temperatures were chosen. The combined microstructure analytics revealed the size and shape of the CdSe nanocrystals and the kind, density and arrangement of planar defects. The role of the planar defects in the particle coarsening by oriented attachment and the effect of the planar fault arrangement on the phase constitution, on the crystallographic coherence of the counterparts and on the optoelectronic properties are discussed.

In this work, the formation and thermal stability of the &omega, Ti(Fe) phase that were produced by the high-pressure torsion (HPT) were studied in two-phase &alpha, Ti + TiFe alloys containing 2 wt.%, 4 wt.% and 10 wt.% iron. The two-phase microstructure was achieved by annealing the alloys at 470 &deg, C for 4000 h and then quenching them in water. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were utilized to characterize the samples. The thermal stability of the &omega, Ti(Fe) phase was investigated using differential scanning calorimetry (DSC) and in situ high-temperature XRD. In the HPT process, the high-pressure &omega, Ti(Fe) phase mainly formed from &alpha, Ti. It started to decompose by a cascade of exothermic reactions already at temperatures of 130 &deg, C. The decomposition was finished above ~320 &deg, C. Upon further heating, the phase transformation proceeded via the formation of a supersaturated &alpha, Ti(Fe) phase. Finally, the equilibrium phase assemblage was established at high temperatures. The eutectoid temperature and the phase transition temperatures measured in deformed and heat-treated samples are compared for the samples with different iron concentrations and for samples with different phase compositions prior to the HPT process. Thermodynamic calculations were carried out to predict stable and metastable phase assemblages after heat-treatments at low (&alpha, Ti + TiFe) and high temperatures (&alpha, Ti + &beta, (Ti,Fe), &beta, (Ti,Fe)).

Three-dimensional (3D) biopolymer-based scaffolds including chitinous matrices have been widely used for tissue engineering, regenerative medicine and other modern interdisciplinary fields including extreme biomimetics. In this study, we introduce a novel, electrochemically assisted method for 3D chitin scaffolds isolation from the cultivated marine demosponge Aplysina aerophoba which consists of three main steps: (1) decellularization, (2) decalcification and (3) main deproteinization along with desilicification and depigmentation. For the first time, the obtained electrochemically isolated 3D chitinous scaffolds have been further biomineralized ex vivo using hemolymph of Cornu aspersum edible snail aimed to generate calcium carbonates-based layered biomimetic scaffolds. The analysis of prior to, during and post-electrochemical isolation samples as well as samples treated with molluscan hemolymph was conducted employing analytical techniques such as SEM, XRD, ATR–FTIR and Raman spectroscopy. Finally, the use of described method for chitin isolation combined with biomineralization ex vivo resulted in the formation of crystalline (calcite) calcium carbonate-based deposits on the surface of chitinous scaffolds, which could serve as promising biomaterials for the wide range of biomedical, environmental and biomimetic applications. © 2020, The Author(s). Politechnika PoznaÅ ska, PUT: 0911/SBAD/0380/2019 Deutsche Forschungsgemeinschaft, DFG: HE 394/3 Deutscher Akademischer Austauschdienst, DAAD Russian Science Foundation, RSF: 18-13-00220 PPN/BEK/2018/1/00071 03/32/SBAD/0906 Sächsisches Staatsministerium für Wissenschaft und Kunst, SMWK: 02010311 This work was performed with the financial support of Poznan University of Technology, Poland (Grant No. 0911/SBAD/0380/2019), as well as by the Ministry of Science and Higher Education (Poland) as financial subsidy to PUT No. 03/32/SBAD/0906. Krzysztof Nowacki was supported by the Erasmus Plus program (2019). Also, this study was partially supported by the DFG Project HE 394/3 and SMWK Project No. 02010311 (Germany). Marcin Wysokowski is financially supported by the Polish National Agency for Academic Exchange (PPN/BEK/2018/1/00071). Tomasz Machałowski is supported by DAAD (Personal Ref. No. 91734605). Yuliya Khrunyk is supported by the Russian Science Foundation (Grant No. 18-13-00220).

The precious metal based High-Entropy Alloy (HEA) AuCuNiPdPt crystallises in a face-centred cubic structure and is single phase without chemical ordering after homogenisation. However, a decomposition is observed after annealing at intermediate temperatures. This HEA shows extended malleability during cold work up to a logarithmic deformation degree of φ = 2.42 . The yield strength ranges from 820 MPa in the recrystallised state to 1170 MPa when strain hardened by cold working with a logarithmic deformation degree of φ > 0.6. This work hardening behaviour is traced back to a steep increase in dislocation density as well as in deformation twinning occurring at low strain. The microstructure and the mechanical properties of AuCuNiPdPt are assessed in detail by various methods. EBSD and TEM analyses reveal mechanical twinning as an important deformation mechanism. The high strength in the recrystallised state is evaluated and found to originate predominantly upon solid solution strengthening.

This chapter presents microstructure features, which are responsible for transformation-induced and twinning-induced plasticity in austenitic steels, gives an overview of relevant microstructure defects and shows how the microstructure defects and their interactions affect the deformation behaviour of these steels. Numerous examples illustrate the capability of scanning and transmission electron microscopy and X-ray and electron diffraction to detect, to identify and to quantify dislocations, stacking faults, twins and their clusters. In this context, the benefits of the in situ techniques of microstructure analysis are emphasized. As the presence and arrangement of stacking faults in austenite play a central role in the plasticity of the austenitic steels, a large part of this chapter is devoted to the characterization and description of their formation, widening and ordering. A novel method for determination of the stacking fault energy is presented that utilizes in situ X-ray or synchrotron diffraction under deformation. Finally, the dependence of the stacking fault energy on the chemical composition of the steel and on the deformation temperature is addressed, and considered as an effective tool for design of steels with desirable mechanical properties.

Composites containing biological materials with nanostructured architecture have become of great interest in modern materials science, yielding both interesting chemical properties and inspiration for biomimetic research. Herein, we describe the preparation of a novel 3D nanostructured MnO2-based composite developed using a carbonized proteinaceous spongin template by an extreme biomimetics approach. The thermal stability of the spongin-based scaffold facilitated the formation of both carbonized material (at 650 °C with exclusion of oxygen) and manganese oxide with a defined nanoscale structure under 150 °C. Remarkably, the unique network of spongin fibers was maintained after pyrolysis and hydrothermal processing, yielding a novel porous support. The MnO2-spongin composite shows a bimodal pore distribution, with macropores originating from the spongin network and mesopores from the nanostructured oxidic coating. Interestingly, the composites also showed improved electrochemical properties compared to those of MnO2. Voltammetry cycling demonstrated the good stability of the material over more than 3,000 charging/discharging cycles. Additionally, electrochemical impedance spectroscopy revealed lower charge transfer resistance in the prepared materials. We demonstrate the potential of extreme biomimetics for developing a new generation of nanostructured materials with 3D centimeter-scale architecture for the storage and conversion of energy generated from renewable natural sources.

The formation of ω-phase under high-pressure torsion (HPT) has been studied in Ti–Fe alloys. Seven alloys with Fe concentration from 0 to 10 wt % have been annealed between 600 and 950 °C, quenched and HPT-treated at 7 GPa, 1 rpm, 5 and 0.1 anvil rotations (equivalent strain eeq = 156 and = 3.1, respectively). The strain after 0.1 rot. corresponds to the transient state of HPT, and that after 5 rot. corresponds to the HPT steady-state and to the dynamic equilibrium between formation and annihilation of microstructure defects. A defect-rich high-pressure ω-phase forms after HPT and persists in the samples also after the pressure release. The amount of retained ω-phase after HPT depends on the iron concentration. It increases from 40% in pure titanium, reaches maximum of 95% at 4 wt % Fe and then decreases again to 10% at 10 wt % Fe. It is because the addition of iron influences the lattice parameters in β and ω-phases in a different manner. The minimal lattice mismatch between β- and ω-phases is reached at 4 wt % Fe. A good conformity between the lattices of the β- and ω-phases enhances the probability of the martensitic (diffusionless) β→ω transformation. Based on the XRD and TEM observations, the crystallography and mechanisms of α→ω and β→ω phase transformations (which can be diffusionless as well as controlled by mass transfer) under the influence of pure shear by HPT are discussed.

Cold gas sprayed Al coatings deposited onto wurtzitic AlN substrates show excellent adhesion. As a possible adhesion mechanism, the local heteroepitaxy between Al and AlN was considered and verified experimentally in Al coatings, which were deposited using magnetron sputtering or cold gas spraying on single-crystalline and polycrystalline AlN substrates. Analysis of the local orientation relationships at the Al/AlN interfaces revealed that preferentially such lattice planes of Al align parallel with the upright lattice planes of AlN, which possess similar interplanar distances. The matching lattice planes in the Al coatings grew as continuations of the lattice planes in the AlN substrates. In all samples under study, the parallel alignment of the lattice planes {220} Al and {110} AlN was found. Additional orientation relationships between Al and AlN arose if parallel lattice planes with similar interplanar spacing could be found in both counterparts via rotation of the lattice planes {220} Al around their normal direction. Still, the oriented growth of Al on AlN is only possible if Al atoms in the deposited coatings are mobile enough to rearrange along the AlN surface. Whereas the mobility of Al atoms in a magnetron sputtering process is expected to be sufficiently high, the intrinsic mobility of Al atoms in the cold gas sprayed particles is anticipated to be low. However, the auxiliary microstructure analyses have shown that local recrystallization and partial melting are two phenomena, which can facilitate the rearrangement of Al atoms within the cold gas sprayed coating.