In this study, TiO2 photoanodes doped with samarium ions via a method of hydrothermal treatment were used to fabricate dye-sensitized solar cells (DSSCs). Different doping concentrations were investigated on the effects of the cell’s performance. Some techniques including XRD, scanning electron microscopy, HRTEM, XPS, UV-Vis, photoluminescence were used to characterize the morphology, structure, and optic properties of the prepared photoanodes. The photovoltaic performance of the fabricated cells was further evaluated by measuring the current density–voltage (J–V) curves. It was found that: (1) The down-conversion luminescence effect derived from samarium doping could enhance the light-harvesting ability. (2) Compared with the undoped sample, the samarium-doped cells exhibited enhanced photovoltaic performance. Among the cells with different doping concentrations, the cell TiO2:0.015 Sm showed the best power conversion efficiency of 6.08% with a high open-circuit voltage (V oc) and a short-circuit current density (J sc).

Here, we demonstrate the enhanced imaging capabilities of an aberration corrected scanning transmission electron microscope to advance the understanding of ion track structure in pyrochlore structured materials (i.e., Gd2Ti2O7 and Gd2TiZrO7). Track formation occurs due to the inelastic transfer of energy from incident ions to electrons, and atomic-level details of track morphology as a function of energy-loss are revealed in the present work. A comparison of imaging details obtained by varying collection angles of detectors is discussed in the present work. A quantitative analysis of phase identification using high-angle annular dark field imaging is performed on the ion tracks. Finally, a novel 3-dimensional track reconstruction method is provided that is based on depth-dependent imaging of the ion tracks. The technique is used in extracting the atomic-level details of nanoscale features, such as the disordered ion tracks, which are embedded in relatively thicker matrix. Another relevance of the method is shown by measuring the tilt of the ion tracks relative to the electron beam incidence that helps in knowing the structure and geometry of ion tracks quantitatively.

N-doped single-crystal-like TiO2 is claimed to be a very promising material among various catalytic. In this paper, N-doped single-crystal-like TiO2 (N-S-TiO2) samples were firstly prepared by molten salt method with urea and mixed nitrates as synergistic doping agents, therein, the mixed nitrates works also as a morphology modifier to form a single-crystal-like structure in the sample. The nitrogen content in the N-S-TiO2 sample could be improved because of the adding of NaNO3 and KNO3 mixed nitrates compared with using urea as a single nitrogen source. UV–Vis absorption spectroscopy analysis indicated that the nitrogen doped TiO2 has a red shift of the light absorption edge. The presence of N–O bonds on the surface of the N-S-TiO2 samples could be confirmed by x-ray photoelectron spectroscopy. The degradation efficiency of N-S-TiO2 to methylene blue under visible light is the best compared with different TiO2 samples without the treatment of mixed nitrates.

Using very long molecular dynamics simulations of duration up to a microsecond of physical time, temperature protocols spanning up to five orders of magnitude in time are performed to investigate thermally activated structural relaxation in a model binary amorphous solid. The simulations demonstrate significant local structural excitations (LSE) as a function of increasing temperature and show that enthalpy rather than internal potential energy is primarily responsible for relaxation. At low temperatures these LSE involve atoms whose displacements are smaller than a typical bond length, whereas at higher temperatures approaching that of the glass transition regime, bond-length displacements occur in the form of string-like motion where one atom replaces the position of another. Such thermally activated excitations are observed to mainly involve the smaller atom type. The observed enthalpy changes can be correlated with the level of internal hydrostatic stress homogenization and icosahedral content within the glassy solid.

Many material manufacturing techniques require the use of nonaqueous colloidal suspensions, containing well dispersed oxide particles and various water insoluble functional components. We report an efficient method for the direct transfer of MnO2 and titania particles, synthesized in water, to an organic solvent through the interface of two immiscible liquids. Particle agglomeration during the drying stage was avoided, and stable suspensions of nonagglomerated particles in the organic phase were obtained. The benefits of this method were demonstrated by the fabrication of advanced composite MnO2-multiwalled carbon nanotube electrodes, containing a polymer binder, for electrochemical supercapacitors with high active mass loading and high active material to current collector mass ratio. The electrodes showed a capacitance of 5.13 F/cm2 and low impedance. High extraction efficiency from concentrated suspensions was achieved by the use of an advanced extractor, which allowed strong adsorption on the particles by the polydentate bonding. The extraction mechanism is discussed.

In the present work, we report the development of phase pure and highly crystalline stibnite Sb2S3 nanostructures by a surfactant-mediated hydrothermal method. Polyvinylpyrrolidone (PVP) as the surfactant has a striking effect on the assembly of nanorods into dumbbell shaped nanorod-bundles. While nanorods with high aspect ratio were formed in absence of the surfactant, dumbbell shaped nanorod bundles were obtained using the surfactant. The structural, morphological, and optical properties were examined by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS), and UV–visible spectrophotometer. Both XRD and Raman spectroscopy confirmed the formation of orthorhombic phase pure stibnite (Sb2S3). The ratio of Sb to S is found to be close to 2:3, corresponding to Sb2S3. The optical band gap varied in the range of 1.65–1.68 eV depending on the concentration of the surfactant.

Selective laser melting, a laser-based additive manufacturing process, can manufacture components with good geometrical integrity. Application of the selective laser melting process for serial production is subject to its reliability on mechanical properties, especially on fatigue behavior, when it is required to be applied for dynamic applications. This study focuses on microstructural, quasistatic, high cycle fatigue (HCF), and very high cycle fatigue (VHCF) mechanisms of aluminum alloys manufactured by selective laser melting. Manufacturing of hybrid structures by selective laser melting process is also investigated. Microstructural features were investigated for process-induced effects and the corresponding influence on quasistatic and fatigue properties. The microstructural features can be controlled in the selective laser melting process for required properties. Joining strengths in hybrid structures can be improved by post process heat-treatments. Material constants in different fatigue regions were determined, and higher fatigue strength of hybrid alloys was achieved in HCF as well as VHCF regimes.

Diatoms microalgae can be regarded as living factories producing nanostructured and mesoporous biosilica shells (frustules) having a highly ordered hierarchical architecture. These unique, morphological, chemical and mechanical properties make diatoms’ biosilica a very attractive nanomaterial for a wide variety of applications. Methods of purification of frustules that preserve their nanostructured morphology have been set up as well as in vivo or in vitro chemical modification protocols of the biosilica with functional molecules to generate biohybrid active materials for photonics, sensing, drug delivery and electronics. Herein we describe, with some selected examples, the great variety of applications envisaged for native and modified frustules, highlighting the material scientists’ benefit to avail of nature in the construction of highly ordered biohybrid architectures for nanotechnology. New concepts for the biotechnological production of nanomaterials are opened by the use of diatoms as living factories.

The interaction between interface dislocation networks and a single lattice Volterra-type dislocation is analyzed by superposition using anisotropic elastic theory in dissimilar materials. The general and nontrivial field solutions for the displacements and stresses are derived by applying the Stroh sextic formalism and Fourier transform in heterogeneous bimaterials. The present approach therefore enables the calculation of the elastic interaction forces for the glide and climb components with different elastic constants and unequal partitioning of elastic fields between adjacent crystals neighboring a semicoherent heterophase interface. Two-dimensional application examples to the pure misfit Au/Cu interface are evaluated, where the infinitely long straight lattice dislocation, parallel to the interface dislocations, is embedded in Au. The repulsive and attractive interaction forces between these two types of (intrinsic and extrinsic) defects are investigated and discussed, for which the results provide a novel basis for examining multiple large-scale dislocation interactions in anisotropic interface-dominated materials with accurate mechanical boundary conditions.

With increasing performance requirements in power electronics, the necessity has emerged to investigate the thermo-mechanical behavior of thick Cu metallizations (≥5 µm). Cu films on rigid substrates in the range of 5–20 µm were thermally cycled between 170 and 400 °C by a fast laser device. Compared to the initial microstructures, a texture transition toward the {100} out-of-plane orientation with increasing film thickness was observed during thermo-mechanical cycling, along with an abnormal grain growth in the {100}-oriented grains and a gradual development of substructures in a crystallographic arrangement. Compared to the well-studied thin Cu film counterparts (≤5 µm), the surface damage showed a 1/hf dependency. Transition from an orientation independent (hf = 5 µm) to an orientation specific thermo-mechanical fatigue damage (hf = 10, 20 µm) was observed following a higher damager tolerance in {100} oriented grains.

Mesoporous silicon sponge (MSS) is considered as a promising anode material for lithium ion batteries because of its preformed meso/macro porous structures that can accommodate large volume expansion during the lithiation process and its superior electrochemical performance. Temperature dependent hyperpolarized (HP) 129Xe NMR was applied to characterize the structure and porosity of MSS materials with varying pores and particle sizes. Our results reveal irregular pore structures with the presence of micropores inside the larger meso/macropore channels and each MSS material has its own characteristic pore environment with a varying degree of nonuniformity and connectivity of pores. This study demonstrates that HP 129Xe NMR is a potentially useful tool for providing a fingerprint of the structure and connectivity of the pores for each material, complementary to other characterization techniques.

Accumulative roll bonding (ARB) process was used to develop Mg–6% Zn/Al and Mg–6% Zn/anodized–Al multilayered composites. Microstructural characterization was done using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscattered diffraction, and transmission electron microscopy. An average grain size measured in the roll-bonded layers of Al, anodized Al, and Mg–2% Zn was found to be 1.8 μm, 1.6 μm, and 0.6 μm, respectively. Phases Al17Mg12, AlMg4Zn11, and Al2O3 after 5-pass of ARB were confirmed by X-ray diffraction analysis. The Mg–6% Zn/Al and Mg–6% Zn/anodized Al composites exhibited tensile strengths ∼252 MPa and ∼256 MPa, respectively, after a 5-pass ARB process. Hardness of the individual layers of composite increased linearly with an increase in the number of ARB passes. Fractographs of the multilayered composite illustrated the ductile failure in Al and anodized Al layers and transgranular brittle fracture in Mg–6% Zn layers.

Many issues concerning the transformation behaviors in the Ni-rich Ti–Ni system remain unresolved, such as the isothermal nature of the B19′-martensitic and R-phase transformations and the precursor phenomena in the B2-parent phase. To clarify the origins of these behaviors, we investigated the transformation latent heat, specific heat, and superelastic behaviors of several Ni-rich Ti–Ni alloys in terms of the entropy change. An anomalous, very wide hump in the specific heat was detected for the B2-parent phase, which can likely be attributed to the precursor phenomenon in the B2-parent phase. In the critical region where the anomalous hump intersects the B19′-martensitic transformation, some evidences of the R-phase transformation were observed, such as a tweed-like microstructure and a specific heat peak with first-order-transformation characteristics. These findings suggest a strong relationship between the R phase and the precursor state in the B2-parent phase.

0.62[0.75(Pb(Mg1/3Nb2/3)O3)–0.25(Pb(Yb1/2Nb1/2)O3)]–0.38(PbTiO3) ceramics were successfully textured in [001] via the template grain growth method using 1–7 vol% platelike BaTiO3 (BT) templated (the Lotgering factor of 0.91 at 5 vol% BT). Dielectric spectra indicated a normal ferroelectric behavior without any frequency dispersion and no low-temperature phase transition. The chemically stable BT phase within the matrix gave rise to a composite effect and its relatively inferior properties affected the dielectric and electromechanical properties. The lower T C of the BT decreased the Curie temperature from 226 to 213 °C (with a depolarization temperature of 204 °C). Significantly higher levels of strain (0.33%), narrower hysteresis level (7.7%), higher piezoelectric strain coefficient (660 pm/V), and low-field (<5 kV/cm) piezoelectric strain coefficient (1340 pm/V) at 50 kV/cm were achieved at 5 vol% BT addition. These results are very promising for the fabrication of high performance transducer and actuator applications without severe temperature limitations.

Recently, in situ characterization methods have attracted increasing attention, especially in organic photovoltaics (OPV) field, since they provide greater insight into the mechanism of film formation, thus help to identify optimized processing conditions used to process the most efficient organic bulk-heterojunction thin films. In combination with various powerful X-ray-based characterization methods, several studies observed the morphological changes under the influence of different processing conditions. In this review, we summarize the fundamentals and implementation of X-ray-based and optical characterization methods, utilized in in situ mode and introduce the reader a better overview of the information acquired from a given technique in terms of microstructure formation in OPV. While we give a chronological development of in situ characterization methods in the field of OPV, we discuss the interplay between thermodynamics of solutions and drying kinetics of different types of organic blends.

Polystyrene spheres were found to be an effective assisted material in the growth of indium-tin-oxide (ITO) nanowire networks, bearing low temperature, high purity, and good control of size. The temperature and time of growth were studied to achieve ITO nanowire networks with high transmission and low resistivity. When prepared by PS spheres of 670 nm dia. for 15 min at 300 °C, the transmittance is above 90% after the wave length of 400 nm, and the sheet resistance is ∼200 Ω/□. Polystyrene-assisted ITO nanowires showed the high degree of crystallinity with lattice fringes, and well coincided cubic phase of In2O3. The density of ITO nanowire networks were controlled by polystyrene spheres and the residual polystyrene was removed by thermal annealing. ITO nanowire networks open new opportunities for optoelectronic devices needing special morphology for the improvement of light extraction efficiency, and as a new type of conductive film, which have an even broad application arena.

A series of Eu3+ and Dy3+ singly and doubly doped Gd2MoO6 phosphors were synthesized with solid state reactions. The X-ray powder diffraction analysis of phosphors shows that substitution of Eu3+ and Dy3+ does not change the host structure of phosphors. The absorption spectra measurements show that un-doped Gd2MoO6 can absorb near ultraviolet light without any visible light emission. However, energy absorbed by Gd2MoO6 can be effectively transferred to doped Eu3+ and Dy3+ and makes them emit blue, yellow, and red light, respectively. White light can be obtained by combining blue, yellow, and red emission. The doping of Dy3+ plays a major role for the formation of white light. The introduction of Eu3+ can remarkably decrease the color temperature of the white light emission. The measurement of the temperature-dependent luminescent properties indicates that the phosphors present a good thermal stability. Our investigation indicates that Gd2MoO6:Eu3+,Dy3+ is a potential candidate for white light emitting diodes applications. It also provides a new sight for the achievement of white light emission.

Nanoindentation techniques are commonly used to characterize nanomechanical properties of microscaled and nanoscaled materials. Nanoindentation using a cylindrical flat-tip indenter has a constant contact area which makes it a reliable source to find material’s yield strength as well as other mechanical properties. However, an angular misalignment of the indenter with the specimen results in experimental error. In this work, the effects of angular misalignment on the nanoindentation testing with a cylindrical flat-tip indenter were numerically analyzed. A three-dimensional nanoindentation solid model was generated, computer modeling based on finite element analysis was conducted. The angle of misalignment ranged from 0° to 1°. Young’s modulus and hardness were evaluated. Based on the hemispherical stress–strain distribution assumption of an elastic plastic indentation, corrected depths and modifiers were proposed for adjusting material’s 0.1% offset and 0.2% offset yield strengths. Low carbon steel AISI 1018 was selected as sample material for indentation testing and modeling validation.

High-porosity metakaolin-based geopolymer foams (GFs) were fabricated by a gelcasting technique using hydrogen peroxide (foaming agent) in combination with Tween 80 (surfactant). Slurries processed in optimized conditions enabled to fabricate potassium based GFs with a total porosity in the range of ∼67 to ∼86 vol% (∼62 to ∼84 vol% open), thermal conductivity from ∼0.289 to ∼0.091 W/mK, and possessing a compressive strength from ∼0.3 to ∼9.4 MPa. Moreover, factors that influence the compressive strength, the porosity, the thermal conductivity, and the cell size distribution were investigated. The results showed that the cell size and size distribution can be controlled by adding different content of surfactant and foaming agent. The foamed geopolymer can also be used as adsorbents for the removal of copper and ammonium ions from wastewater. The foams, due to their low thermal conductivity, could also be used for thermal insulation. It was also possible to produce geopolymer formulations that could be printed using additive manufacturing technology (Direct Ink writing), which enabled to produce components with nonstochastic porosity.

Electrochemical sensing systems are advancing into a wide range of new applications, moving from the traditional lab environment into disposable devices and systems, enabling real-time continuous monitoring of complex media. This transition presents numerous challenges ranging from issues such as sensitivity and dynamic range, to autocalibration and antifouling, to enabling multiparameter analyte and biomarker detection from an array of nanosensors within a miniaturized form factor. New materials are required not only to address these challenges, but also to facilitate new manufacturing processes for integrated electrochemical systems. This paper examines the recent advances in the instrumentation, sensor architectures, and sensor materials in the context of developing the next generation of nanoenabled electrochemical sensors for life sciences applications, and identifies the most promising solutions based on selected well established application exemplars.