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High-resolution transmission electron microscopy observations on rapidly solidified Nd-Fe-B alloys are presented. The results show the existence of nanophases of different compositions to the nominal Nd2Fe14B as-prepared alloy, which was detected prior to the fast-quenching process. In particular, iron-enriched nanophases are commonly found among the wide variety of nanophases in the final alloy. The possible mechanisms, as well as their relevance to the understanding of the properties of these magnetic materials, are also discussed.

A master alloy with eutectic compositions of Ni-30.26Mo-6.08Al-1.43 V (wt%) has been directionally solidified (DS) into γ/γ'-α alloy. The microstructural as-ageing treatment was studied by means of high resolution electron microscopy (HREM). A majority of α fibres still display the Bain orientation relationship with the γ'/γ matrix. In a few cases, however, the so-called Nishiyama-Wasserman (NW) orientation relationship is found in specimens aged at 850 o C for 2000 h. Different microdomain structures of the γ phase, corresponding to different ageing temperatures, were revealed. Orthorhombic Ni 3 Mo phase, with a size of tens of nanometres, was found to precipitate inside α fibres after ageing at both 850 and 650 o C. Occasionally, an γ'-Ni 3 Al phase with lamellar twin structure was also found to coexist with Ni 3 Mo precipitate inside the α fibres. The orientation relationships between the precipitates and the α fibres were determined. Energy dispersive X-ray analysis (EDX) showed that the precipitation of Ni 3 Mo and Ni 3 Al is due to solid solution of Ni and Al in the α fibres

A master alloy with eutectic compositions of Ni-30.26Mo-6.08Al-1.43 V (wt%) has been directionally solidified (DS) into γ/γ′-α alloy. The microstructural as-ageing treatment was studied by means of high resolution electron microscopy (HREM). A majority of α fibres still display the Bain orientation relationship with the γ′/γ matrix. In a few cases, however, the so-called Nishiyama-Wasserman (NW) orientation relationship is found in specimens aged at 850 °C for 2000 h. Different microdomain structures of the γ phase, corresponding to different ageing temperatures, were revealed. Orthorhombic Ni3Mo phase, with a size of tens of nanometres, was found to precipitate inside α fibres after ageing at both 850 and 650 °C. Occasionally, an γ′-Ni3Al phase with lamellar twin structure was also found to coexist with Ni3Mo precipitate inside the α fibres. The orientation relationships between the precipitates and the α fibres were determined. Energy dispersive X-ray analysis (EDX) showed that the precipitation of Ni3Mo and Ni3Al is due to solid solution of Ni and Al in the α fibres.

The microstructure of an Al2O3-24 vol% ZrO2 composite prepared by pressureless-sintering was investigated by high-resolution electron microscopy. The composite was formed of homogeneously dispersed ZrO2 and Al2O3 grains with average sizes of 0.3 and 0.5 μm, respectively. Most ZrO2 grains had a monoclinic structure, but a few ZrO2 embedded in Al2O3 grains were a tetragonal structure. At interfaces between ZrO2 with a lamella-type twin structure and Al2O3, microcracks were observed, in addition to strain fields in the Al2O3 matrix. Complex twin structures accompanied by dislocations were observed in ZrO2 with a spherical shape. In in situ observations with electron-beam heating, it was found that a crack propagated along an Al2O3/ZrO2 interface and stopped at the place where a tetragonal ZrO2 had undergone a structural change to monoclinic ZrO2.

As a catalyst, partially crystallized Fe78Si12B10 alloy shows a three times higher activity than totally crystallized Fe78Si12B10 in the hydrogenation of CO. High-resolution electron microscopy (HREM) reveals that the catalyst contains a great number of minute (less than 10 nm), highly dispersed α-Fe particles which act as the major active component. Many tiny B and Si oxide clusters also exist in the amorphous matrix. After being rinsed by a NaOH solution, the catalyst exhibits a decreasing selectivity to methane due to the dissolution or aggregation of B and Si species. After reaction, the sizes of the active particles increase and an overlayer of B or Si species is found over the surface of some α-Fe particles. This coverage is thought to be the primary origin of the deactivation of the catalyst.

A high-resolution electron microscopy study was preformed on two high-strength aluminium alloys, an Al-6.2Cu-0.4Ag-0.4Mg-0.2Zr alloy and a similar alloy but having a low lithium addition (1.25 wt%), named Weldalite 049, in order to identify their principal strengthening phase. The lattice images of the principal strengthening phase in these alloys were found to be different. The former alloy had the so-called Ω phase, which agrees with previous publications, whereas Weldalite 049 had a phase similar to, but not exactly like, the so-called T1 phase which is the principal strengthening phase of some high lithium (≧2 wt%) AlCuLi alloys.

The microstructures of unhydrated calcium aluminosulphate Ca4Al6SO16 and Ca3SrAl6SO16 have been studied by high-resolution electron microscopy (HREM). The results showed that twinning and twinned slabs could be introduced taking the [1 1 2] direction as the twin axis so that it seems to be coincident with the law of twinning formed in body-centred cubic structures. A previously reported superlattice with a repeat period twice that of the fundamental structure along the 〈1 1 0〉 direction has also been found in both matrix and twin variants. The close intergrowth of Ca3SrAl6SO16 and another phase, possibly Sr3Al2O6 existing as an inclusion between these two twin variants, was determined and clearly revealed by electron diffraction and HREM images. The coherent interphase boundaries and orientation relationship between them can also be deduced.

High-resolution transmission electron microscopy was performed on vacuum-deposited nanocrystalline nickel aluminide films. Several nickel aluminide ordered structures, i.e. L12(Ni3Al)-, B2(NiAl)-, D513(Ni2Al3)- and D020(NiAl3)-type structures, were observed in the deposited films. The L12 and B2 ordered structures became unstable with decreasing grain sizes. The critical grain size on transformation from the L12- and B2-type ordered structures into disordered structures was ca. 5 nm at ambient temperatures. High atomic diffusion, sufficient for grain growth, and an increase in the ordering occurred just above 400°C in the nanocrystalline Ni-Al films with L12- and B2-type structures. The diffusion bonding process, at ambient temperatures, between Ni-Al nanocrystallites with an L12-type structure was observed dynamically at atomic resolution under strong electron irradiation. It was found that the nanocrystallites rotated and slid without crack generation, and neck-growth proceeded even at ambient temperatures.

The cubic-tetragonal transition of V-Ru alloys near 50 at % has been investigated by high resolution transmission electron microscopy. In the cubic to tetragonal transition process of thin foil specimens, we found an incommensurate modulated structure showing satellite spots near 1/4 〈0 1 1〉 positions in the electron diffraction patterns. This incommensurate structure is composed of many domains of the commensurate modulated structure with a pseudotetragonal cell of A=B=2(a 2 + c 2)1/2 and C=c, where a and c (∼1.07a) are the lattice constants of the tetragonally distorted CsCl-type structure. The modulation is interpreted in terms of the combination of dual elastic shear distortion waves nearly parallel to the 〈0 1 1〉 directions with the approximate wavelength of 2√2a. We propose a model for the incommensurate modulated structure.

Although facilities for high resolution electron microscopy (HREM) are available, interpretation of micrographs at high magnifications is far from unambiguous. The interpretation of the micrographs using a computed structure analysis program is therefore necessary. The paper presents the theory behind HREM, together with a computer method for image interpretation. Special reference is made to the JEOL JEM 200CX transmission electron microscope used in the study of sodium beta-alumina.

Crystals of poly (p-phenylene sulphide) were obtained from anα-chloronaphthalene solution. The chain axis (the crystalc-axis) was usually normal to the support-film. For these crystals, high-resolution electron microscopic images were taken as the projection of the molecular chains on theab plane along the chain axis. Occasionally it was observed that crystals took different orientations on the support-film for undefined reasons. From such orientations, the high-resolution image of a crystal rotated by 28.7° around thea-axis from the usual orientation, was also obtained.

The structure of tetrahedrally close-packed phases (known also as Frank-Kasper phases) in superalloys has recently been extensively studied at the atomic level by high-resolution electron microscopy (HREM) in the Laboratory of Atom Image of Solids, Academia Sinica. In addition to a magnitude of domain structures, no less than six new phases have been found. This is a resume of the study. First, a brief description of the crystal structures of these phases is given to illustrate the capability of HREM in revealing the building of complex structures from simple structural units. Secondly, the crystallographic features of the new phases and microdomain structures are discussed. Finally, the principle of juxtaposition of parallel oriented coordination polyhedra in these tetrahedrally close-packed phases is presented and this not only explains the existing structures of such phases but may also be important in the study of the quasi-crystalline state in rapidly quenched amorphous alloys.

The microstructures of belite examined by high-resolution electron microscopy (HREM) show the (1 0 0) and (0 0 1) twin lamellae which are introduced by shear stresses during the transformation ofα′−C2S toβ-C2S.γ-C2S formed in the larnite was identified and the orientation relationship between them was also determined by a composite electron diffraction pattern (EDP), which is different from that suggested earlier by Groves. The EDP and the HREM image showed the existence of the unstable phaseα′L−C2S.

The relationship between radiation damage and the application of high resolution electron microscopy (HREM) to polydiacetylene single crystals has been examined. The damage is seen to occur by the decay of electron diffraction patterns and the loss of contrast in bright- and dark-field micrographs. The rate of damage was found to be different for the two polydiacetylene derivatives studied and to take place probably by cross-linking. It was found that lattice images from planes parallel to the chain direction with a spacing of 0.9±0.1 nm could be obtained from the most resistant derivative. Images of chain-end dislocations were obtained for the first time in a polymer crystal. The problems of applying HREM to polymers and the conditions for imaging individual molecules are discussed.

A high-resolution electron microscope observation (HREM) was performed on the joined portion of a brazed polycrystalline or single crystal SiC to itself with (Ag-28wt% Cu) + 2wt% Ti alloy foil. The brazing was done under vacuum at temperatures of 800° C to 950° C with a holding period of up to 30 min. Reaction products formed at the joined interface were found to be mainly TiC. In the specimen brazed at 800° C with the holding time of 0 min, reaction product TiC formed itself into small crystallites with a diameter of less than 20 nm, and an amorphous like layer was found between SiC and TiC. On the other hand, TiC was formed as a layer along the joined interface for the specimen brazed at 950° C for the holding time of 30 min. Lattice matching of SiC to TiC crystals appeared to be good so the high bonding strength of the joint was attributed to the formation of this epitaxial interface between SiC and TiC.

The microstructure of a series of Ni-B alloys (15 at%

The microstructural evolution of Al–2.24 Cu–1.42 Mg–0.9 Fe–0.9 Ni (AA2618) alloy after 195 °C/18 h aging, as well as after 180 and 240 °C/100 h creep, has been studied by transmission electron microscopy and high resolution electron microscopy (HREM). The Guinier–Preston–Bagaryatsky (GPB) zones/co-clusters, S″, S, and Al9FeNi phases co-exist in the alloys after the 195 °C/18 h aging. After creep, precipitates become coarser and the transformation of GPB zones/co-clusters and S″ to S phase take place. A large number of GPB zones/co-clusters as those in aging state exist after 180 °C/100 h creep which possibly dynamically precipitates during the creep process. After the 240 °C/100 h creep, most of the precipitates are S variants with a few GPB zones and S″ phase. More dislocations appear upon which precipitate colonies form after creep. HREM images show that most of the early precipitates less than about 5 nm cannot exhibit perfect lattice image for the existence of stress. However, certain GPB/co-clusters possessing coherent relationship with the matrix can also be observed. HREM demonstrates that certain S particles viewed along [100]S and [013]S have classic orientation relationship with the matrix, and that those upon the dislocations depart from the standard orientation.

The effects of copper addition on the machinability and corrosion resistance of martensitic stainless steel 4Cr16Mo are presented in the article. The results showed that the machinability of stainless steel 4Cr16Mo was obviously improved by adding Cu. When the content of copper in the stainless steel was 1.4%, the machinability of stainless steel was optimal. With the increase in the content of copper, the corrosion resistance of stainless steel 4Cr16Mo was improved. From the observation of the electron backscattered diffraction (EBSD) and high resolution electron microscopy (HREM), it can be seen that Cu-rich phases were dispersed in the stainless steel, and determined to be about 10 nm.

The structures of martensites in a Cu–11.2 wt% Al–3 wt% Ni specimen, which was quenched from 1173 K, have been studied by high resolution electron microscopy (HREM) and diffraction techniques. Two kinds of martensites, i.e. β′1 and γ′1, coexisting adjacent to each other in the specimen were observed. The γ′1 matensite consists of microtwins with monoclinic structure. Three variants of the twin structure, i.e. {1 2 1}, {2 1 0} and {1 0 1} twins, are arranged within a single plate. The β′1 martensite possesses basically ordered N9R structure, but mixed with thin 2H domains. Some diffraction spots of this martensite shift along the [0 0 1] direction. In addition, extra weak reflections appear in the diffraction pattern due to heterogeneous atomic displacements. The microstructural features of the martensites are examined and discussed.

The fine structure of unhydrated cement clinker Ca4Al6SO16 (C4A3S) and its four superstructures have been studied by means of electron diffraction and high resolution electron microscopy (HREM). The match between experimental images and simulated ones verifies the result of X-ray structural analysis: C4A3S having a cubic lattice with space group l43m,Z = 2. The frequent apperance of forbidden reflections such as 1/2, −1/2, 0 along the 〈110〉* directions of C4A3S imply the presence of superstructures which may be due to an orderly inverse occupation of Ca2+ ions. Various structure models based upon the observed structural images have been proposed for these four superstructures. A new cubic phase witha′ = 1.5 nm is also found by selected area electron diffraction (SAED).

Two kinds of bulk mesophases separated by quinoline from Polyvinylchloride (PVC) pitch and from 3, 5-xylenol-formaldehyde resin (XF) pitch were studied by high resolution electron microscopy. The ease of graphitization of both bulk mesophases has been examined by heat-treating them up to 1080 and 2600° C. PVC bulk mesophase mostly shows preferred long range orientation (aromatic carbon layers roughly parallel to each other), but also contains minor components where the molecular orientation occurs only over small distances, or not at all. When heat-treated at high temperature PVC bulk mesophase changes mainly into highly graphitized lamellar crystals. Similarly treated XF bulk mesophase does not show any preferred orientation and leads to porous nongraphitizable material.

Ca- and P-based bioactive glasses are excellent candidates for design and manufacture of biomaterials. Understanding the structure and physico-chemical–thermal behaviour of bioactive glasses is a fundamental step towards the design of a new generation of biocompatible materials. In this study, the structure of SiO2–CaO–Na2O glasses and its derivatives, obtained by substituting Na2O with P2O5 and prepared by melt–quench technique, was studied with neutron and electron diffraction techniques combined with thermal analysis, high-resolution electron microscopy and X-ray photoelectron spectroscopy. Neutron and electron diffraction data were analysed with reverse Monte Carlo simulation and pair distribution function analysis, respectively. Bioactivity of P2O5 substituted glasses was also investigated and proven in vitro using simulated body fluid. Based on the structural analysis, it was found that Si and P atoms are in well-defined tetrahedral units with a bond distance of 1.60 Å for both Si–O and P–O bonds, although P exhibits a higher average coordination number than Si. With increasing phosphate content, tendentious changes in the glass behaviour were observed. Linear increase in Tg, supported by the changes in the average coordination numbers of Si and P, indicates strengthening of network structure with increasing P content and formation of P–O–Ca atomic linkages, which lead to Ca–P-rich atomic environments in the silicate network. These Ca–P-rich environments trap volatile elements and thus decrease the total weight loss during heating at higher P concentrations. In the case of the highest investigated P2O5 content (5 mol%), nanoscale structural inhomogeneity and the formation of Ca–P-rich clusters were also revealed by electron diffraction and atomic resolution imaging. This type of Ca–(Na)–P clustering has a key role in the behaviour of phosphate-substituted silicate glasses under physiological conditions.

[EN] In this study, a facile, cheap, scalable, and environmentally friendly method has been developed to prepare nanostructured TiO2 coatings with a high catalytic activity. In addition, a protocol to characterize the prepared films in order to obtain consistent results between their structure, their microstructure, and their catalytic behavior, has been established. For that, two types of TiO2 coatings have been fabricated by applying once TiO2 aqueous suspensions, prepared form commercial nanopowders, by immersion followed by an adequate thermal treatment. The first type of films is constituted by coatings with anatase as single phase, and the second one by films with a rutile molar fraction of XR = 0.07  0.02, determined from grazing incidence X-ray diffraction (GI-XRD) data. High spatial resolution chemical imaging, obtained by confocal Raman microscopy (CRM), of the surface and of the cross-section for the films shows a good distribution of rutile without any segregation of this phase. Furthermore, high resolution electron microscopy (HREM) confirmed the presence of anatase/rutile biphasic domains in those areas in which both phases were previously found together by CRM. In addition, the catalytic data fit to a first-order kinetic model with high catalytic reaction constants (k’), especially when rutile is present. Furthermore, consistent results have been found in this study between textural, structural and microstructural features with catalytic properties for the prepared TiO2 films., This work was supported by MINECO (Government of Spain) and Feder Funds under Grant no. MAT2016-78700-R. The authors are also grateful to Mrs. C. Díaz-Dorado for her help in the preparation of FEG-SEM, TEM, and HREM pictures.

The precipitation hardening behavior of Al–5.1Mg–0.15Cu alloy with 3.0Zn (wt%) addition at various temperatures has been systematically investigated in this study. The Al–5.1Mg–0.15Cu–3.0Zn alloy possesses the higher strength compared with traditional Zn-free alloy, when the alloy is treated at 363 K for 24 h and subsequently aged at 413 K for 25 h. The precipitation sequence of the hardening phase T-Mg32(AlZn)49 is investigated by differential scanning calorimetry tests, transmission electron microscopy and high-resolution electron microscopy. The different effects of natural aging and pre-aging on the precipitation hardening behavior are detailed. The formation of relatively stable Guinier–Preston zones of T-Mg32(AlZn)49 phase during pre-aging rather than natural aging results in higher mechanical strength during subsequent artificial aging at relatively high temperatures. When the Al–5.1Mg–0.15Cu–3.0Zn alloy is aged at 453 K, the peak hardness is from synergetic effect of hardening of S-Al2CuMg phase and coarsening of T phase. However, during two-step artificial aging treatment, the peak hardness results from fine, spherical and homogeneously distributed T phase in the absence of the S phase.

GdB44Si2 is an excellent thermoelectric material, and nanostructured GdB44Si2 makes it possible to potentially improve its properties further. GdB44Si2 nanowires and nanobelts have been fabricated by chemical vapor deposition and characterized by electron diffraction and high-resolution electron microscopy. These nanostructures are of the YB50 structure and grew in the [010] direction. The nanowires have thickness of less than 100 nm and length of several tens of microns. The nanobelts have thickness of about a few tens of nanometers. Morphological and compositional analyses confirmed that the nanowire growth followed the vapor–liquid–solid mechanism and the nanobelts were formed by a subsequent vapor–solid process of condensation.

peer-reviewed Porous silicon finds numerous applications in the areas of bio-technology, drug delivery, energetic materials and catalysis. Recent studies by Vesta Sciences have led to the development of porous silicon nanosponge particles from metallurgical grade silicon powder through their own patented chemical etching process (Irish patent no. IE20060360). This discovery paves the way for a more economical production method for porous silicon. The study presented here studies the structural morphology of the porous silicon nanosponge particles using high resolution electron microscopy techniques combined with porisometry type measurements, where appropriate. The related surface pore structure is examined in detail using Scanning Electron Microscopy and Transmission Electron Microscopy techniques while the internal pore structure is explored using Focused Ion Beam milling and ultramicrotomed cross-sections. Three samples of the silicon particles were analysed for this study which include the starting metallurgical grade silicon powder and two samples that have been chemically etched. Analysis of the etched samples indicates a disordered pore structure with pore diameters ranging up to 15 nm on porous silicon particles ranging up to 5 mu m in size. Crystallographic orientation did not appear to affect the surface pore opening diameter. Internal pore data indicated pore depths of up to 1 mu m dependant on the particle size and etching conditions applied. accepted peer-reviewed

Nanosized Se4+ and Te4+, respectively, doped titania was prepared by homogeneous hydrolysis of titanium oxo-sulfate with urea in aqueous solutions in the presence of amorphous selenium and tellurium. The prepared samples were annealing at temperature 200 and 400 °C. The structure of prepared samples was characterized by X-ray powder diffraction (XRD), selected area electron diffraction (SAED), surface area (BET), and porosity determination (BJH). The morphology and microstructure characteristics were obtained by scanning electron microscopy (SEM) and high-resolution electron microscopy (HRTEM). The method of UV/Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies of the Se and Te-doped titania. The photocatalytic activity of the prepared samples was assessed by the photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 and 400 nm wavelength. The best photocatalytic activity in UV and visible area exhibit the Se and Te-doped titania samples labeled TiSe3 (~11.5 wt% Se) and TiTe3 (~8.0% Te), respectively.

The microstructure formation and phase transformations in Ti2AlC-rich coatings deposited by High Velocity Oxy-fuel spraying of Maxthal 211(A (R)) powders is presented. High resolution electron microscopy analysis, using both scanning and transmission electron microscopy with energy dispersive spectrometry and energy filtering, combined with X-ray diffraction reveals that the coatings consist of Ti2AlC grains surrounded by regions of very small TiC grains embedded in Ti (x) Al (y) . The composition of the Ti (x) Al (y) depends on its surrounding and varies with size and distribution of the adjacent TiC grains. Impact of spray parameters on coating microstructure is also discussed. Two spray parameters were varied; powder size distribution and flame power. They were found to greatly affect the coating microstructure. Increasing powder size and decreasing flame power increase the amount of Ti2AlC, but produces thinner coatings with lower cohesion. Larger powder size will also decrease oxygen incorporation.

Detailed crystallographic data on high-quality Li2MnO3 material has been obtained using a combination of X-ray diffraction (XRD), selected-area electron diffraction (SAED), high-resolution electron microscopy (HREM), and 0.1 nm probe high-angle annular dark-field imaging (HAADF) in a scanning transmission electron microscope. A high-purity Li2MnO3 powder was annealed at 950 °C for 3 days to obtain predominantly defect-free grains which average size was 3.0 ± 1.5 μm. Rietveld refinement indicated that the C2/m spacegroup provided the best fit for the XRD data. Electron diffraction patterns obtained along various zone axes, on defect-free oxide particles, could be uniquely indexed to the monoclinic structure. HREM and HAADF images of defect-free grains were consistent with a Li–Mn–Mn– arrangement, i.e., lithium ordering in the transition metal planes. Low-magnification TEM images occasionally revealed stacking defects within oxide particles. HREM images of sample areas containing defects revealed a low density of stacking faults within the monoclinic sequence, resulting in a trigonal P3 1 12 local arrangement.

Sol–gel TiO2 porous matrix was used to host valproic acid (VPA) and phenytoin (DPH), which are commonly used as antiepileptic drugs. The addition of these drugs was carried out during the synthesis in the hydrolysis stage. In vitro short term kinetic studies on drug liberation showed that almost all samples followed a first order kinetics with the exception of one sample which had a linear behavior. High resolution electron microscopy revealed the existence of nanocrystalinity in all samples, however, electron diffraction patterns showed that some were predominantly amorphous while in others suggested a greater density of nanocrystals. NMR studies demonstrated that VPA was less mobile in a more crystalline TiO2 matrix than when the TiO2 is mainly amorphous. Some features of the kinetics of drug liberation are explained in terms of the competition between nanocrystallinity and drug content. The reservoirs were implanted by means of stereotactic surgery in Wistar rats in which epilepsy was previously induced following the Kindling model of epilepsy. The efficiency of the reservoirs was follow by electroencephalography (EEGs). In vivo studies revealed that a more crystalline sample was more effective in preventing further epileptic events than samples with a higher content of VPA but predominantly amorphous.

Electron irradiation-induced phase change in tungsten was examined by in situ high resolution electron microscopy. In samples prepared by a chemical polishing technique using a NaOH aqueous solution, an α to β phase change was induced under 200 keV electron irradiation at 773 K. It is suggested that sodium atoms deposited on the tungsten sample from the solution, rather than oxygen atoms, may play an essential catalytic role in inducing the phase change.

In the present work, Fe-montmorillonite (Fe-MMT) was synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The polyamide6 (PA6)/organic-modified Fe-montmorillonite (Fe-OMT) composite nanofibers were prepared by facile compounding and electrospinning. Fe-OMT was first dispersed in N, N-dimethyl formamide and then compounded with PA6 which was dissolved in formic acid. The composite solutions were electrospun to form PA6/Fe-OMT composite nanofibers. The structure, morphology, thermal stability, and crystalline properties of the composite nanofibers were characterized by Fourier transfer infrared (FTIR) spectra, Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), High-resolution electron microscopy (HREM), Scanning electron microscopy (SEM), and Thermogravimetric analyses (TGA), respectively. It was found that the silicate clay layers were well exfoliated within the composite nanofibers and were oriented along the fiber axis. The SEM images indicated that the loading of Fe-OMT decreased the diameters of composite nanofibers. TGA analyses revealed that the thermal stability was notably improved in the presence of silicate clay. It was also observed from wide-angle XRD analyses that the presence of nanoclays improved the γ-form crystals and induced the formations of α-form crystals of the PA6, attributed to effective nucleating effects of silicate clay platelets.

Boron nitride (BN) nanotubes, nanohorns and nanocoils were synthesized by annealing Fe4N/B, FeB and Fe/B powders at 1000 °C for 1–24 h in nitrogen gas atmosphere, and large amounts of BN nanotubes were obtained by annealing Fe4N/B. The growth mechanism and atomic structures were investigated on cup-stacked BN nanotubes synthesized from Fe4N/B by X-ray diffraction, high-resolution electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. As-produced BN soot was purified by removing non-BN nanomaterials such as metal catalyst particles and unreacted boron, and high purity BN nanotubes were obtained.

Secondary phases and grain boundaries in LaCoO3 and La0.7Sr0.3CoO3−δ ceramics have been studied by transmission electron microscopy. Both materials contained small amounts of grains of a secondary phase; the face centered cubic spinel structure Co3O4, located at triple junctions. These grains were agglomerates of several smaller grains. High resolution electron microscopy combined with annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy were used to analyze the grain boundaries. In LaCoO3, the grain boundaries were sharp with stable compositions of La, Co and O across the boundaries. In La0.7Sr0.3CoO3−δ, a 1–2 nm thick intergranular layer between the grains was observed. This layer was rich in O and Co and deficient in Sr and La, compared to the nominal composition of the material.

Poly (styrene-acrylonitrile) (SAN)/clay nanocomposites have been prepared by melt intercalation method from pristine montmorillonite (MMT), using hexadecyl trimethyl ammonium bromide (C16) and hexadecyl triphenyl phosphonium bromide (P16) as the reactive compatibilizers between polymer and clay. The influence of the reactive compatibilizers proportion relative to the clay on the structure and properties of the SAN/clay nanocomposites is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), high-resolution electron microscopy (HREM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The effects of the two different clays (MMT and organic modified MMT) on the nanocomposites formation, morphology and property are also studied. The results indicate that the SAN cannot intercalate into the interlayers of the MMT and results in microcomposites. In the presence of the reactive compatibilizers, the dispersion of clay in SAN is rather facile and the SAN/clay nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and the presence of small tactoids. The appropriate proportion with 3 wt% reactive compatibilizers to 5 wt% MMT induces well-dispersed morphology and properties in the SAN matrix. The TGA analyses show that the thermal stability properties of the SAN/clay nanocomposites have been improved compared with those of the pristine SAN. The DMA results show that the storage modulus and glass transition temperature (Tg) of the SAN/clay nanocomposites have remarkably enhancements compared with the pristine SAN. At last the intercalation mechanism of the technology is discussed.

In this paper, a novel polyacrylamide(PAM)/α-zirconium phosphate(α-ZrP) nanocomposite was successfully synthesized by exfoliation-adsorption and in-situ intercalative polymerization. The microstructure of PAM/α-ZrP nanocomposites was confirmed by X-ray diffraction measurement, transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM). The results suggested that the α-ZrP lamellae were dispersed well in PAM matrix, which indicated the formation of the exfoliated nanocomposites in the low inorganic loading of α-ZrP (≤5 wt%). With the increase of the inorganic loadings, the intercalated structure of PAM/α-ZrP nanocomposites was dominant with the d-spacings of about 1.50–1.58 nm corresponding to the inorganic loadings in the range of 10–20 wt%. Moreover, besides the electrostatic adsorption, it was also found that there may be some weak effect such as hydrogen bonding or protonation between the host and guest investigated using fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (TG )analysis, which resulted in the enhancement of the thermal properties on the decomposition process of PAM/α-ZrP nanocomposites by the retardant effect of the exfoliated or intercalated α-ZrP nanometer lamellae.

The novel polyurethane/montmorillonite (PU/MMT) nanocomposites based on poly (propylene oxide) glycol (POP), 4,4′-diphenymethylate diisocyanate (MDI), 1,4-butanediol (1,4-BD) and MMT has been synthesized using a one-step direct polymerization-intercalation technique by twin-screw extruder. Its structure and thermal properties are characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and High-resolution electron microscopy (HREM), Fourier-transform infrared spectroscopy (FTIR) and Thermogravimetry analysis (TGA), respectively. The results of XRD and HREM analyses show that the silicate layer is well dispersed in PU matrix and this mesostructure can be considered as a delaminated nanocomposites. The TGA analysis indicates that the thermal stability properties of the PU/MMT nanocomposites are increased slightly compared with the pristine PU, due to the increase of the char residue. The mechanical and flammability performances are examined by electronic Universal Tester and Cone calorimetry, respectively. The layered silicate, which acts as a high aspect ratio reinforcement, enhances tensile strength of the PU. Specifically, there is a 25% increase in the tensile strength of PU nanocomposites containing 4 wt.% MMT compared with that of pristine PU. However, the elongation at break of PU/MMT nanocomposites is lower than that of pristine PU. The loading of MMT leads to the remarkably decrease of heat release rate (HRR), contributing to the improvement of flammability performance.

β-FeSi2 embedded in a Si matrix was prepared by ion beam synthesis (IBS). Two step implantation, with energies 60 and 20 keV, of two different doses of the iron ions, 5 × 1015 and 5 × 1016 cm−1, was performed. After the implantation, the samples were subjected to rapid thermal annealing (RTA) at 900 °C. The crystal structure of the resulting material was studied using cross-sectional transmission electron microscopy (XTEM), including high-resolution electron microscopy (HREM). The comparison of the XTEM images with the initial iron ions implantation profiles, simulated by SRIM (Stopping and Range of Ions in Matter) demonstrate that the process of IBS, followed by RTA, preserves the initial implantation profile, implying a negligible Fe atoms diffusion velocity in comparison with the one of the chemical reaction between Fe and Si. The XTEM images show that continuous β-FeSi2 layers are fabricated when there is a stoichiometric region in the initial implantation profile. Fe concentration lower than the stoichiometric one in the whole implantation range results in formation of β-FeSi2 nanocrystallites embedded in the Si matrix. The behavior of the absorption coefficient energy dependences, obtained from the optical transmittance and reflectance measurements, reflects the different crystal structures forming in the two types of samples.