In this work, the morphology of BiFeO3 was successfully modulated from microsphere to microcube by using a polyanion, poly (methyl vinyl ether-alt-maleic acid) (PMVEMA), in a microwave assisted hydrothermal route. A simple ultrasonic purification method has been developed to obtain pure phase BiFeO3 from the crude products without using any chemicals. X-ray diffraction results confirmed the capability of this purification method. When increasing the amount of PMVEMA, the morphology of BiFeO3 gradually changed from microsphere to microcube as illustrated by scanning electron microscopy. A mechanism was suggested for the morphology evolution of BiFeO3. After the formation of the small BiFeO3 single crystal, PMVEMA preferentially absorbed on one side of the crystals through specific and/or noncovalent interactions, resulting in the preferential integration of these crystals to form microcubes. The magnetic properties of these microcrystals were also investigated and the magnetization of the microcubes increased with the decrease of temperature.

Er3+-doped oxyfluoride transparent glass and glass-ceramics (GCs) containing SrF2 nanocrystals were prepared and their spectroscopic properties were investigated. The formation of SrF2 nanocrystals in GCs has been confirmed by x-ray diffraction (XRD) and transmission electron microscopy. The Judd-Ofelt (JO) parameters have been evaluated from absorption spectra of the Er3+-doped glass and GCs, which are used to predict radiative properties for some important luminescence levels of Er3+ ions in glass and GCs. The XRD and JO parameters suggest that the Er3+ ions are progressively incorporated into the SrF2 nanocrystals in the GCs compared with glass. The up-conversion luminescence intensity increases significantly in GCs with increase in time of thermal treatment. The lifetime of the 4S3/2 level of the Er3+ ions in GCs is found to be slightly higher than that in the glass due to the incorporation of Er3+ ions into the lower phonon energy of SrF2 nanocrystals in the GCs.

Ceramic parts possessing an ordered porosity were produced for the first time by powder-based three-dimensional printing of a preceramic polymer followed by pyrolysis in an inert atmosphere. The main parameters involved in the process were investigated, and the precision of the printed and ceramized parts was assessed by means of scanning electron microscopy and micro computed tomography. The influence of two different printing solvents was investigated and the use of a mixture of 1-hexanol and hexylacetate in particular allowed the production of parts with a relative density of 80% both in the polymeric and in the ceramic state. The mixing of a cross-linking catalyst directly with the printing liquid greatly simplified the process, minimizing the necessity of preprocessing the starting powder. Three-dimensional printing of a preceramic polymer not containing any inert or active fillers was proved to be a feasible, convenient and precise process for the production of porous ceramic possessing a complex, ordered structure, such as stretch-dominated lattices.

Stable, responsive and autofluorescent genipin-crosslinked chitosan–poly(vinyl pyrrolidone) hydrogels have been synthesized. Morphological characterization techniques such as scanning electron microscopy, environmental scanning electron microscopy, and in situ confocal laser scanning microscopy (CLSM), in both reflectance and fluorescence modes, have been compared for their suitability to characterize the network structure of these hydrogels. CLSM is shown to be the optimal technique owing to the facile generation of the three-dimensional porous architecture and extra topographical information while the sample is immersed in the aqueous solution to which it will find application. CLSM is used in both reflectance and fluorescence modes to follow morphology variation as a function of time during swelling. Conveniently, acquisition via reflectance produces images with a higher degree of structural detail than fluorescence, widening the application of this method to characterize hydrogels where addition of a fluorescent probe, which may alter the native structure, is undesired.

The present work demonstrates the synthesis of Cu–10 wt% TiB2 composites with a theoretical density of more than 90% by tailoring the spark plasma sintering (SPS) conditions in the temperature range of 400–700 °C. Interestingly, 10 wt% Pb addition to Cu–10 wt% TiB2 lowers the sinter density and the difference in the densification behavior of the investigated compositions was discussed in reference to the current profile recorded during a SPS cycle. The sintering kinetics and phase assemblage were also discussed in reference to surface melting of the constituents prior to bulk melting temperature, temperature dependent wettability of Pb on Cu, diffusion kinetics of Cu as well as the formation of various oxides. An important result is that a high hardness of around 2 GPa and relative density close to 92% ρtheoretical was achieved for the Cu–10 wt% TiB2–10 wt% Pb composite, and such a combination has never been achieved before using any conventional processing route.

A high open-circuit voltage (VOC) of an organic photovoltaic device (OPV) has been realized using an ultrathin electron donor layer, 2,3-Bis(2-(diphenylamino)-9,9′- spirobifluorene-7-yl)fumaronitrile (PhSPFN), which exhibits the most suitable and low-lying highest occupied molecular orbital (HOMO) to align between the anode and donor energy levels. The planar heterojunction OPV, represented as indium tin oxide electrode/PhSPFN/fullerene C60/bathocuproine/aluminum electrode shows high performance with a VOC of 0.91 V, short current density of 3.9 mA/cm2, fill factor of 56% and power conversion efficiency of 2% under an air-mass of 1.5 global illumination at 1 sun. In addition, the effect of the VOC change is discussed in terms of various donor materials. The VOC turns out to be restricted to the energetic alignment between the work function of the anode and the HOMO level, indicating that the optimization of VOC requires energetically good contact between the anode and organic materials.

A novel and simple method for gelcasting of alumina was developed using a nontoxic and water-soluble copolymer of isobutylene and maleic anhydride (commercially called Isobam). In this method, there is requirement of only a small amount of Isobam (0.3 wt%) and neither initiators nor dispersants are needed for preparation and gelation of a 50 vol% solids loaded alumina slurry. The gelation rate increased with increasing solids loading but decreased with increasing Isobam content. A typical gelation time was 38 min for the slurry containing 50 vol% solids loading and 0.3 wt% Isobam. The resultant wet gel was strong enough to allow reversible bending and twisting. This simple gelling system is attractive for wet forming of ceramics because only a single additive, which acts as both dispersant and gelling agent at room temperature in air, is used.

The use of MgO nanoparticle (NP) loaded poly(methylsilsesquioxane) (PMSQ) as a low temperature processable composite dielectric has been investigated. The composite dielectrics have been synthesized using facile ultrasonic mixing of trimethoxymethylsilane (MTS), butanol (n-BuOH) and deionized water at 60 °C, with MgO loadings from 0.096 up to 0.39 wt% of the initial solution. Thin films of the composite materials produced have shown an increase in dielectric constant from 2.8 for raw PMSQ up to 3.4 for the 0.39 wt% loaded PMSQ + MgO NP composites at frequencies up to 2 MHz, comparable to 3.9 for SiO2. The composite dielectric materials have shown suitability as a dielectric material for a P3HT OFET, with the performance comparable to a standard SiO2 dielectric control sample.

In this work, we report on the optoelectronic and photocatalytic features of europium (Eu3+)-doped TiO2 nanoscale particles synthesized via a sol-gel mediated rapid-condensation technique. X-ray diffraction studies have revealed the mixed phases of the synthesized systems. In particular, a mixture of anatase, brookite, and rutile phases was found to coexist beyond a sintering temperature of 600 °C while a pure anatase phase was witnessed below 500 °C. The photoluminescence spectra of ∼7 nm sized anatase TiO2 nanoparticles have exhibited different intra 4f (Eu3+ ion related) transitions with the most intense red emission (5D0→7F2) peak located at ∼613 nm. The emissions due to color centers and oxygen vacancies of TiO2 were also evident in the PL spectra. The Brunauer-Emmett-Teller surface area analysis has revealed a significant increment of surface area and pore volume owing to the enhanced interfacial region introduced by point defects and dislocations due to Eu doping. The photocatalytic activity of the Eu3+ doped TiO2 nanoscale system was found to be ∼12% stronger than its un-doped counterpart, as assessed from the degradation of methyl orange (MO) solution under UV light irradiation. The percentage of degradation was found to be strongly dependent on the duration of the UV exposure and Eu doping concentration. As an efficient photosensitive candidate, rare earth sensitized TiO2 systems would bring new insights while displaying both optoelectronic and photocatalytic characteristics through use of the localized states present in the band gap of the host.

The porous Li1.2Ni0.13Co0.13Mn0.54O2 nanoplate is prepared by colloidal crystal template assembled by the poly (methyl methacrylate) (PMMA) beads. Scanning electron microscopy and transmission electron microscopy results show that the nanoplates of porous solid solution cathodes are composed of nanoparticles with a size range of 30 nm, which interweave together forming an open porous structure. Electrochemical tests show that porous Li1.2Ni0.13Co0.13Mn0.54O2 cathode could deliver higher discharge capacity than that of bulk Li1.2Ni0.13Co0.13Mn0.54O2 cathode at all C-rates. The enhanced structural stability reflected by high ratios of integrated Intensity I(003)/I(104) and lattice parameters c/a, high specific surface area, a fast reaction and ionic diffusion kinetics of the nanoplates are considered attributable to the improved electrochemical properties.

Ice templating is able to do much more than macroporous, cellular materials. The underlying phenomenon—the freezing of colloids—is ubiquitous, at a unique intersection of a variety of fields and domains, from materials science to physics, chemistry, biology, food engineering, and mathematics. In this review, I walk through the seemingly divergent domains in which the occurrence of freezing colloids can benefit from the work on ice templating, or which may provide additional understanding or inspiration for further development in materials science. This review does not intend to be extensive, but rather to illustrate the richness of this phenomenon and the obvious benefits of a pluridisciplinary approach for us as materials scientists, and for other scientists working in areas well outside the realms of materials science.

A kinetics model for the precipitation of M23C6 in high Cr ferritic heat resistant steel during tempering has been developed assuming the site-saturated nucleation, carbon diffusion-controlled growth and soft-impingement. The growth coefficient in this model is temperature-dependent, and the Arrhenius equation is applied to describe the growth coefficient, in which the growth activation energy is nearly equal to the diffusion activation energy of carbon in martensite. The effect of main parameters in this model has been discussed in detail. By this model, the precipitation of M23C6 during tempering can be predicted accurately in the case of 2D, and a good agreement with experimental data in previous work has been achieved.

Multilayer Si/Ge heterostructures with the thickness of Ge layers varying from 2 to 12 monolayers (MLs) were formed by molecular beam epitaxy on the (001) Si substrates at 300 °C (Ge) and 450 °C (Si). Using conventional and aberration corrected scanning transmission electron microscopy, x-ray reflectometry and x-ray standing waves, a thorough study of the Si/Ge heterostructures was performed. Optical properties of the heterostructures were probed by photoluminescence spectroscopy. It is shown that the growth of Ge layers up to a thickness of 5 ML occurs through the Frank–van der Merwe mechanism. For thicker Ge layers the growth mechanism of the Si–Ge heterostructure changes to Stranski–Krastanov with Si–Ge islands having the shape of inverted pyramids. We discuss the intermixing of Si and Ge due to stress induced interdiffusion. An explanation of the influence of the observed structural peculiarities on the PL spectra of the heterostructures is given.

Textured epitaxial HfO2 thin films of monoclinic structure were grown on r-cut Al2O3 by atomic layer deposition from HfCl4 and H2O at temperatures 450–750 °C. The film-to-substrate out-of-plane orientation was determined to have a single (001)HfO2//(1$\bar 1$02)α-Al2O3 relationship. The in-plane orientation showed the existence of two possible relationships: [100]HfO2//[110]α-Al2O3 and [$\bar 1$00]HfO2//[110]α-Al2O3. In films deposited at 400 °C traces of (010) growth plane were observed in addition to the preferential (001) growth. The lattice of HfO2 was compressed in the surface plane and expanded in the surface normal direction. The strain was highest in the films grown at 450–550 °C. With the increase of deposition temperature to 750 °C, the strain decreased. The strain relaxation in films deposited at 750 °C was in correlation with marked surface roughening in the initial stage of deposition at this temperature. The roughness of the epitaxial films was lower than that of polycrystalline films with comparable thickness deposited on Si(100) and SiO2 substrates.

A physical model is developed for the enhancement of the Seebeck coefficient (S) in a porous thermoelectric material with inhomogeneous porosity. The pores are assumed to be hole and of spherical shape. We take into account the presence of trap centers situated at pore/medium interfaces and neglect changes in the carrier effective mass due to the band-bend. We show that the porosity always leads to an increase in the absolute value of S. A simple relation is derived for S in nondegenerate n-type semiconducting materials in the case when the main contribution in the carrier relaxation time at zero porosity is from the scattering on acoustic phonons. We have shown that the value of S does not depend on the orientation of the porosity gradient with respect to the direction of the temperature gradient. The relative growth of the Seebeck coefficient compared to its value in the bulk material of the same volume is examinated for different number of the pore groups with different characteristic sizes at various pore size distributions.