The plastic deformation of the Zr64.13Cu15.75Ni10.12Al10 and Cu60Zr30Ti10 bulk metallic glasses (BMGs) with arc-shaped edges were performed by compression. Highly dense shear bands with an average spacing of 520 nm are uniformly distributed in a large area in Zr64.13Cu15.75Ni10.12Al10 BMG, and the shear band spacing can be reduced to a minimum value of about 110 nm. In the region adjacent to the dense shear band zone in Zr64.13Cu15.75Ni10.12Al10 BMG, the shear band spacing increases linearly. Similarly, highly dense shear bands were also introduced into Cu60Zr30Ti10 BMG. When the width of stress concentration zone is of the order of plastic zone size ahead of crack tip, the internal and external stress limitations can lead to the formation of a large number of uniformly-distributed shear bands. In addition, the pre-existing dense shear bands can lead to a non-localized plastic deformation manner for deformed Zr64.13Cu15.75Ni10.12Al10 BMG.

•Hardness of deformed BMG shows initial decrease and subsequent increase with plastic strain.•Free volume induced softening contributes to the initial decrease in hardness.•Shear band intersections lead to the subsequent increase in hardness.Introduction of shear bands in metallic glasses is usually regarded as being responsible for softening metallic glasses. Here we present that hardness of deformed Zr64.13Cu15.75Ni10.12Al10 bulk metallic glass (BMG) exhibits an initial decrease and a subsequent increase with plastic strain. This extraordinary variation of hardness was studied by investigating evolution of shear band intersections and free volume with plastic strain. As plastic strain increases from 6% to 83%, the density of shear bands increases from 0.04 to 0.92 μm−1. Meanwhile, the distribution width of shear band spacings gradually narrows, and the number of intersections between shear bands increases. When plastic strain is larger than 47%, the number of intersections increases faster. Free volume in the deformed BMG at room temperature increases with plastic strain increasing from 6% to 83%. Both free volume induced softening and shear band interaction induced hardening may affect the hardness of the deformed BMG. In the plastic strain range of 0%–47%, free volume induced softening mainly contributes to the initial decrease in hardness with plastic strain. In the plastic strain range of 47%–83%, shear band interaction induced hardening may lead to the increase in hardness with plastic strain, after counteracting free volume induced softening.

Well-dispersed spherical amorphous alumina nanoparticles with a narrow size distribution were obtained by facile homogeneous precipitation and subsequent calcination. In the synthesis, formamide was used as the precipitant, and mixtures of aluminum sulfate and aluminum nitrate with different molar ratios were used as the aluminum sources. The average size of the amorphous alumina nanoparticles was successfully controlled by adjusting the amount of formamide and the sulfate/nitrate molar ratio. The particle size decreased with increasing amount of formamide and decreasing sulfate/nitrate molar ratio. Dispersed spherical amorphous alumina nanoparticles with average sizes of 23, 34, 45, and 57 nm were prepared using 100 mL formamide at sulfate/nitrate molar ratios of 1:9, 2:8, 3:7, and 4:6, respectively.

A series of (Zr64.13Cu15.75Ni10.12Al10)100−xTix (x=0–7) bulk metallic glasses were prepared by water-cooled copper mold casting method. The glass forming ability, crystallization behavior, and plasticity of the (Zr64.13Cu15.75Ni10.12Al10)100−xTix alloys with different Ti contents were studied. The reduced glass transition temperature increases with Ti addition and a maximum value of 0.562 is achieved at x=5, indicating that the glass forming ability increases with Ti addition. Compared with that of one crystallization step for the sample without Ti addition, the Ti (x≥2) containing alloys exhibit a two-step crystallization behavior. In addition, the initial crystallization temperature decreases from 744 to 684 K as x increases from 0 to 7. Icosahedral quasicrystal phase was found to precipitate in the amorphous matrix in the first crystallization step, implying that strong icosahedral short-range order may exist in the Ti (x≥2) containing alloys. Moreover, the (Zr64.13Cu15.75Ni10.12Al10)100−xTix bulk metallic glasses exhibit excellent plasticity, i.e., a plastic engineering strain in compression larger than 80% for x≤6.

•Monodisperse, spherical, and porous γ-Al2O3 nanoparticles with an average size of 90 nm.•The γ-Al2O3 nanoparticles inherits the porous structure from the aluminum basic sulfate particles.•Dimethylamine borane was used for the first time to produce aluminum basic sulfate particles.Using dimethylamine borane (DMAB) as a precipitator, monodisperse and spherical aluminum basic sulfate particles with an average diameter of 96 nm and a narrow size distribution from 75 to 127 nm were prepared by a homogeneous precipitation route. By calcining the aluminum basic sulfate particles at 950 °C for 2 h, the γ-Al2O3 nanoparticles with a spherical shape, an average size of 90 nm, and no agglomeration were obtained. The aluminum basic sulfate particles and the γ-Al2O3 nanoparticles have a porous structure. The monodisperse porous γ-Al2O3 nanoparticles have an average pore diameter of 9 nm and a pore size distribution from 2 to 16 nm.Monodisperse and spherical aluminum basic sulfate particles with an average diameter of about 96 nm and a narrow size distribution from 75 to 127 nm were prepared by a homogeneous precipitation route. By calcining the aluminum basic sulfate particles at 950 °C, the γ-Al2O3 nanoparticles with a spherical shape, an average size of 90 nm, and no agglomeration were obtained. The aluminum basic sulfate particles and the γ-Al2O3 nanoparticles have a porous structure.

Microstructures play an important role in materials’ functional performances. In this work, the microstructures including interfaces induced microwave resonance peak shift of Co/Al2O3 nanocomposites is studied. Nanosized Co/Al2O3 composites were successfully fabricated via direct ball milling. The hcp and fcc Co phases coexist for a long milling duration and the interface effect is prominent in the nanocomposites. The measured relative complex permittivity of the Co/Al2O3 nanocomposite–paraffin wax mixture indicates that a high electrical resistivity and a dielectric loss exist in the Co/Al2O3 nanocomposites. The dielectric loss mainly arises from the polarization of the metal/insulator interfaces. The imaginary part of the relative complex permeability of the mixture exhibits a broad resonance peak centered at 8.3 GHz which originates from the natural resonance of Co. In comparison to the reported value 6.5 GHz, the shift of the resonance peak to higher frequency can be attributed to the surface anisotropy induced by prominent interface effects, which was confirmed by NMR. The position of the resonance peak results from the competition between the surface anisotropy and the dipolar coupling interaction of the Co grains. The calculated reflection loss curves show that the reflection loss value of the Co/Al2O3 nanocomposite–paraffin wax mixture can reach −10 dB in a broad frequency range. The improved microwave characteristics are closely related to the microstructures, and can be tailored by controlling the content of Co and the thickness of the sample.Highlights► The Co/Al2O3 nanocomposites were prepared by ball milling. ► The microstructures of the Co/Al2O3 nanocomposites were characterized. ► The microwave absorption properties of the Co/Al2O3 nanocomposites were measured. ► The microwave resonance peak shift induced by interfaces was found. ► The Co/Al2O3–paraffin wax mixture shows good microwave absorption in a broad range.

High-energy ball milling was employed to induce plastic deformation of Zr70Cu20Ni10 metallic glass ribbons, resulting in intersected and branched shear bands with a minimal spacing of about 30 nm. Crystallization was not observed in the shear bands. The free volume content in the deformed metallic glass increases with increasing duration of ball milling. Compared with the as-spun metallic glass, 28.8% more free volume is introduced in the metallic glass after ball milling for 80 h.Highlights► Shear bands with a minimal spacing of about 30 nm were induced by ball milling. ► The mean atomic volume of the ball-milled metallic glass is about 1% higher. ► 28.8% more free volume is introduced in the ball-milled metallic glass.

•Ni nanoplatelets of different sizes are synthesized by solution reduction method.•A thin oxide layer was formed on the surface of Ni nanoplatelets.•Increased size dependence of Ni nanoplatelets' lattice constants was observed.•Coercivity of the Ni nanoplatelets increased with its mean diameter.•The cause of the size dependence of its lattice constant and coercivity was analyzed.Ni plate-like nanoparticles (or nanoplatelets), with a mean diameter in the range from 42 to 130 nm and a thickness of about 10 nm, were synthesized by solution reduction method. Increased crystallite-size dependences of the lattice constant and the coercivity were observed. The cause for the variation of the lattice constant and the coercivity of Ni nanoplatelets with their size was investigated, respectively.

A novel, facile, green and template-free approach was developed for the fabrication of amorphous zinc citrate yolk–shell microspheres and crystalline ZnO yolk–shell nanospheres. In this approach, the amorphous zinc citrate yolk–shell microspheres were prepared through a single chemical reaction at low temperature (90 °C) and with room temperature ageing. The zinc citrate yolk–shell microspheres have an average size of about 1.25 μm. The average diameter of the inner cores and the average thickness of the outer shells are 500 nm and 150 nm, respectively. The effect of ageing time on the morphology of the zinc citrate microstructures was analysed. As the ageing time increases from 0 to 12 h, the zinc citrate microstructure transforms from a solid microsphere through a yolk–shell microsphere to a hollow microsphere. The ZnO solid nanospheres, yolk–shell nanospheres and hollow nanospheres can be prepared via the perfect morphology inheritance of the zinc citrate solid microspheres, yolk–shell microspheres and hollow microspheres, by calcination at 600 °C for 2 h. The ZnO yolk–shell nanospheres show the largest visible emission and the highest photocatalytic activity.

γ-Al2O3 nanoparticles with a porous structure and spherical shape, agglomerated from finer crystallites, were synthesized via a glycothermal route by using sodium oleate as surfactant and template. Disperse and spherical aluminum hydroxide nanoparticles with an average particle size of 77 nm were prepared first by a glycothermal method. After calcining the aluminum hydroxide nanoparticles at 900 °C and eliminating the organic template, disperse, spherical, and porous γ-Al2O3 nanoparticles with an average particle size of 50 nm, agglomerated from 2–10 nm crystalline particles, were obtained. The pore sizes in the porous γ-Al2O3 nanoparticles range between 1.8 and 10 nm.Highlights► Disperse, spherical aluminum hydroxide nanoparticles are prepared by a glycothermal method. ► Porous γ-Al2O3 nanoparticles of 50 nm agglomerated from 2–10 nm crystals. ► Porous γ-Al2O3 nanoparticles show pore size distribution between 1.8 and 10 nm.

This paper reports morphology-tuned synthesis of arrayed one-dimensional ZnO nanostructures on Ag-coated glass substrates from Zn(NO3)2 and dimethylamine borane (DMAB) aqueous solutions and their photoluminescence and photocatalytic properties. By adjusting the Zn(NO3)2 concentration in the solutions, the ZnO nanoneedle arrays, nanorod arrays, and polycrystal films can be obtained. Low Zn(NO3)2 concentrations result in ZnO nanoneedle arrays. The ZnO nanoneedles grow along the 〈0 0 0 1〉 directions. The growth process of the ZnO nanoneedles at low Zn(NO3)2 concentrations goes through the formation of the equiaxial ZnO granules, the growth of the equiaxial granules into small nanorods, the growth of the small nanorods into nanoneedles, the growth of the nanoneedles in diameter and length, the growth of the nanoneedles into nano-obelisks, and the growth of the nano-obelisks into thick hexangular rods. So the morphologies of the arrayed 1D ZnO nanostructures can be tuned from arrayed nanoneedles through arrayed nanorods and nano-obelisks to arrayed thick hexagonal rods by controlling the Zn(NO3)2 concentration in the DMAB and Zn(NO3)2 solutions and/or the deposition time in our process. The ZnO nanoneedle arrays have the largest ratio of the visible to ultraviolet emission and the highest photocatalytic activity.Highlights► Morphology-tuned synthesis of arrayed one-dimensional ZnO nanostructures. ► Solution synthesis process in Zn(NO3)2 and dimethylamine borane solutions. ► Arrayed nanoneedles, arrayed nanorods, nano-obelisks, and thick hexagonal rods.

The effect of Al2O3 content on the structure, electrical properties, magnetic properties, and interparticle exchange interactions of (Fe65Co35)1 − x(Al2O3)x films with Al2O3 volume fractions x ranging from 0 to 0.50 was systematically investigated. Among the films with x between 0 and 0.25, the lowest coercivity of 0.56 kA/m was achieved in the (Fe65Co35)0.82(Al2O3)0.18 film. This is ascribed to the strongest exchange interactions between the Fe65Co35 nanoparticles in this film. Combined with the microstructure analysis of the (Fe65Co35)1 − x(Al2O3)x films, the modified Herzer's model was extended to interpret the variation of the coercivity with x and analyze the effect of the exchange interactions between the Fe65Co35 nanoparticles on the magnetic softness. The remanence curves confirm the existence of the exchange interactions and reveal the evolution of the exchange interaction strength with Al2O3 content.Highlights► (Fe65Co35)1 − x(Al2O3)x films were deposited by radio frequency magnetron sputtering. ► Increasing Al2O3 content decreases the average Fe65Co35 nanoparticle size. ► For 0 ≤ x ≤ 0.25, the lowest coercivity was achieved in the (Fe65Co35)0.82(Al2O3)0.18 film. ► Low coercivity is ascribed to the strong interparticle exchange interactions. ► The exchange interaction strength is related to the Al2O3 content.

This paper reports the synthesis of Eu3+ ions-doped Y2SiO5 (Y2SiO5:Eu3+) powders by mesoporous template route. Using mesoporous silica SBA-15 as silica source, Y2SiO5:Eu3+ powders were prepared by solid-state reaction at a calcination temperature of 1300 °C without fluxes. The prepared Y2SiO5:Eu3+ powders were characterized by X-ray diffraction, scanning electron microscope, nitrogen adsorption–desorption isotherms, and photoluminescence spectroscopy. The results show that the crystalline Y2SiO5:Eu3+ particles are dense and have a morphology similar to SBA-15. The low calcination temperature is attributed to the high reactive activity of SBA-15 with large surface area and non-crystalline structure. The Y2SiO5:Eu3+ powders prepared at a low calcination temperature show luminescence properties similar to the reported results of Eu3+ doped-Y2SiO5 samples prepared at high temperatures.Research highlights► Synthesis of Y2SiO5:Eu3+ using mesoporous silica SBA-15 at 1300 °C. ► Low solid state reaction temperature because of the high reactive activity of SBA-15. ► Morphology of the dense crystalline Y2SiO5:Eu3+ particles similar to SBA-15. ► Luminescence of Y2SiO5:Eu3+ prepared using SBA-15 similar to conventional Y2SiO5:Eu3+.

FeCoAlN films were prepared by reactive radio frequency magnetron co-sputtering technique in an argon and nitrogen mixture atmosphere. The soft magnetic properties, GHz dynamic properties, and magnetic thermal stability of the FeCoAlN films were investigated. The FeCoAlN films deposited at N2/(Ar + N2) gas flux percentages larger than 8% have amorphous structure. The (Fe64.8Co35.2)96.3Al3.7N film as-deposited at the N2/(Ar + N2) gas flux percentage of 9% has good magnetic softness and uniaxial in-plane anisotropy, as demonstrated by the typical hysteresis loops along easy and hard axis. The magnetic thermal stability of the FeCoN films can be obviously improved by introduction of a high Al content. The (Fe64.8Co35.2)86.5Al13.5N films annealed at 400 °C for 1 h exhibit good magnetic softness and GHz dynamic properties with a saturation magnetization (μ0Ms) of 1.21 T, an easy axis coercive field (Hce) of 8.5 Oe, an anisotropy field (Hk) of 35 Oe, a ferromagnetic resonance frequency (fr) of 1.89 GHz, and a real part of permeability (μ′) of 380. The dynamic characteristics can be described by the theoretical model based on Landau-Lifshitz-Gilbert (L-L-G) equation and eddy current dynamics.

Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol–gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.

This paper reports a simple and novel process for preparing nano-granular ZnxFe3−xO4 ferrite films (0 ≤ x ≤ 0.99) on Ag-coated glass substrates in DMAB-Fe(NO3)3-Zn(NO3)2 solutions. The deposition process may be applied in preparing other cations-doped spinel ferrite films. The Zn content x in the ZnxFe3−xO4 films depends linearly on the Zn2+ ion concentration ranging from 0.0 to 1.0 mM in the aqueous solutions. With x increasing from 0 to 0.99, the lattice constant increases from 0.8399 to 0.8464 nm; and the microstructure of the films changes from the non-uniform nano-granules to the fine and uniform nano-granules of 50–60 nm in size. The saturation magnetization of the films first increases from 75 emu/g to the maximum 108 emu/g with x increasing from 0 to 0.33 and then decreases monotonously to 5 emu/g with x increasing from 0.33 to 0.99. Meanwhile, the coercive force decreases monotonously from 116 to 13 Oe.

Using X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry, the effects of room-temperature rolling and subsequent annealing treatment on the microstructure and crystallization behavior of the Zr55Cu40Al5 metallic glass ribbons have been investigated. High density of shear bands with spacings less than 100 nm and ordered clusters of 3–5 nm in size in the shear band regions were observed in the room-temperature rolled Zr55Cu40Al5 metallic glass ribbons. In addition, the rolling deformation changes the crystallization behavior of the Zr55Cu40Al5 metallic glass during the isothermal annealing treatment and results in the formation of a new crystalline phase.

The effects of pH value on the composition, structure, morphology, and phase transformation of aluminum hydroxides prepared by chemical precipitation were studied. Aluminum hydroxide precipitated at the pH values of 5 and 6 is amorphous and transforms to α-Al2O3 at 950 °C via the amorphous aluminum hydroxide → amorphous Al2O3 → α-Al2O3 transformation path. Aluminum hydroxide precipitated at pH = 7 is boehmite and transforms to α-Al2O3 at 950 °C via the γ-AlOOH → γ-Al2O3 → α-Al2O3 path. Aluminum hydroxide precipitated at pH values in the 8 to 11 range is bayerite and transforms to α-Al2O3 at 1000 °C via the α-Al(OH)3 → γ-Al2O3 → ε-Al2O3 + θ-Al2O3 → α-Al2O3 path. Moreover, the pH value affects not only the morphology of aluminum hydroxide particles which changes from ultrafine floccules through 50 nm blowballs then to 150 nm irregular agglomerates with increasing pH value but also the microstructures of final decomposition products of aluminum hydroxides.The influences of pH value on composition, microstructure, and phase transformation of aluminum hydroxide precipitated from aluminum nitrate with ammonia were studied. At pH = 5 and pH = 7, precipitates are ultrafine amorphous aluminum hydroxide floccules and 50 nm boehmite blowballs, respectively; at pH = 9, precipitate is 150 nm irregular bayerite agglomerates. The different precipitates transform into α-Al2O3 at different temperatures via different transformation sequences.

Cobalt nanoplatelets with hexagonal close-packed crystal structure have been synthesized through the reduction of cobalt chloride by NaH2PO2 in a mild aqueous solution without surfactant used. X-ray diffraction analysis reveals that the as-prepared samples are pure HCP cobalt. Transmission electron microscope observations indicate that the synthesized particles are plate-like in form and have the diameter between 150 and 220 nm and thickness of about 10 nm. A selected-area electron diffraction analysis shows that the perpendicular direction of the Co nanoplatelets is a [0 0 1] crystallographic direction. X-ray photoelectron spectroscopy analysis implies that the surface of the Co nanoparticles was oxidized in air and formed CoO layer. Magnetic measurements reveal that the Co nanoplatelet powder samples are ferromagnetic. The saturation magnetization of the Co nanoplatelet powder samples is lower than the corresponding bulk value. The coercivity is as high as 263 Oe.

Ni0.11ZnxCo0.03Fe2.86-xO4 spinel ferrite films with x = 0.00, 0.23, 0.34, 0.43 and 0.51 were prepared on Ag-coated glass substrates from nitrate and dimethylamine borane solution at 80 °C. The Ni0.11ZnxCo0.03Fe2.86-xO4 ferrite films are singe-phased spinel ferrite. With the Zn content x increasing from 0 to 0.51, the lattice constant of the ferrite films increases from 0.8383 to 0.8425 nm. The Ni0.11Zn0.51Co0.03Fe2.35O4 film is about 500 nm thick and composed of uniform equiaxed granules of about 40–50 nm. The Raman spectrum analysis indicates that the Zn2+ ions occupy the A sites. Saturation magnetization increases with x increasing from 0 to 0.35, reaches a maximum value of 460 kA/m at x = 0.35, and then decreases with further increase of x. Coercivity decreases monotonically from 12.3 to 1.7 kA/m with x increasing from 0 to 0.51. The change in magnetic properties may be explained by the decrease of A–B interactions and the anisotropy constant due to the incorporation of non-magnetic Zn2+ ions.

Palladium-containing SBA-15 (SBA-15-Pd) was synthesized via an in situ approach. In this procedure, molecular assembly template was employed as a hydrophobic carrier to provide the compatible environment for the hydrophobic compounds. The hydrophobic solvent (CHCl3) was used as a transport medium to inject the Pd precursor (Pd(acetylacetonate)2) directly into the inner core of the surfactant micelles. A 1.46 wt% Pd loading was achieved without the loss of pore ordering. Highly dispersed and uniform palladium nanoparticles could be detected using transmission electron microscopy confirming also the absence of large particles outside the mesopore silica. The catalytic activities of the SBA-15-Pd nanocomposites were investigated in Heck coupling reactions with activated and non-activated aryl substrates. The SBA-15-Pd nanocomposites exhibit excellent catalytic activities and reuse ability in air for the Heck carbon–carbon coupling reactions.

Pd nanoparticles of 6–10 nm in size have been synthesized by formalin reduction method and incorporated into mesoporous SBA-15 silica during hydrothermal synthesis. Characterizations of the Pd nanoparticles encapsulated in mesoporous silica (Pd/SBA-15) reveal that the Pd nanoparticles in the range of 6–10 nm are encapsulated within the surfactant micelles during mesoporous silica formation and well dispersed within the mesoporous SBA-15 channels. The pore size increases and the surface area decreases with the incorporation of the Pd nanoparticles into SBA-15. The catalytic activity of Pd/SBA-15 was investigated in Heck coupling reactions with activated and non-activated aryl substrates. The Pd/SBA-15 composite exhibits an excellent catalytic activity, low Pd leaching, and reuse ability of at least five recycles in air for the Heck carbon–carbon coupling reaction.

Ordered mesoporous silica thin films have been prepared on silicon substrates by spin-coating technique using poly(alkaline oxide) triblock copolymers EO20PO70EO20 (P123) as structure-directing agent. The X-ray diffraction and transmission electron microscopy investigations show that the obtained mesoporous silica thin films have an ordered pore array structure in nanoscale. The atomic force microscopy analysis reveals that the obtained mesoporous silica thin films exhibit a tile arrangement structure in micron scale.

(Fe81Co19)N thin films were prepared by reactive radio frequency magnetron sputtering in an argon and nitrogen mixture atmosphere. The as-deposited (Fe81Co19)N thin films have a high saturation magnetization (μ0Ms) of up to ∼ 2.36 T and good soft magnetic properties. The grain size and magnetoelastic effects strongly affect the soft magnetic properties of the (Fe81Co19)N thin films due to the introduction of nitrogen into Fe(Co) lattice. The high frequency characteristics of the (Fe81Co19)N thin films were examined in 0.1 to 7 GHz frequency range using a shorted microstrip transmission-line perturbation method. The (Fe81Co19)N thin films with lower nitrogen contents exhibit a high permeability over 400 at low frequency and a high resonance frequency of up to 2.8 GHz. The thin films with higher nitrogen contents have stripe domain structures and yield distinct multiple-peak permeability spectra.

The Co nanoplatelets of 120 nm in diameter and 10 nm in thickness exist in both fcc and hcp crystal structures at room temperature. The saturation magnetization of the Co nanoplatelets is lower than that of the bulk Co because of the existence of the oxide layer. The coercivity is higher than that of the bulk Co. The equilibrium magnetic configuration of a single Co nanoplatelet without external magnetic field is a vortex structure, regardless of hcp or fcc crystal structure. The Co nanoplatelets were coated by MnO2. The microwave properties of the MnO2-coated Co nanoplatelet composites and paraffin wax mixtures were measured in the 0.1–18 GHz frequency range. The complex permeability of the sample shows two broad resonance peaks and the complex permittivity of the sample shows one resonance peak in the frequency range of 0.1–18 GHz. The numerical simulations show that the reflection loss values of the MnO2-coated Co nanoplatelet composites and paraffin wax mixtures are less than −12 dB in the 2–11.5 GHz frequency range.

Titania–nickel nanocomposite coatings consisting of a nanocrystalline nickel matrix (average grain size: 10 nm) and nanometer-sized titania particles dispersed in the nickel matrix on copper substrates were prepared by simultaneous electrodeposition of nickel and titania from a nickel electrolyte in which the titania particles were suspended. The nanocomposite coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Vickers microhardness tests, and corrosion tests. The results indicate that the concentration of the titania particles in electrolytes affects the content of titania in the composite coatings. Vickers microhardness and corrosion resistance of the nanocomposite coatings increase with increasing content or decreasing grain size of titania particles in the composite coatings. The nanocomposite coatings containing anatase nanoparticles have a higher hardness and lower corrosion rate compared with those containing rutile microparticles.

Co plate-like nanoparticle (or nanoplatelet) samples with different hcp phase contents were synthesized by a novel reduction process. The thickness-to-diameter aspect ratio of the nanoplatelets is between 1:10 and 1:50. The normal direction of the nanoplatelets is perpendicular to the close-packed crystallographic planes. The saturation magnetization of the nanoplatelet powders is lower than the corresponding bulk value. The magnetization configuration of the nanoplatelet is a vortex structure without external magnetic field. The coercivities of the nanoplatelets increase with the hcp phase content.

Zr61.7Al8Ni13Cu17Sn0.3 bulk metallic glass samples with different aspect ratios in the range of 0.25–2.25 were deformed by compression, and the effect of aspect ratio on the evolution of shear bands was investigated. It is found that for the deformed Zr61.7Al8Ni13Cu17Sn0.3 bulk metallic glass, the average shear band spacing decreases and the shear band density increases monotonically as the aspect ratio increases from 0.25 to 2.25. A minimal average shear band spacing of 0.478 µm is achieved for the sample with an aspect ratio of 2.25. In addition, the fractions of shear bands with spacings below 100 and 50 nm are about 12.84% and 6.76%, respectively, for the sample with an aspect ratio of 2.25. The reason for the formation of a higher density of shear bands can probably be attributed to the increase of the driving force for the sample with a larger aspect ratio.

Fine nanoparticles (NPs) exhibit higher sintering activity than large ones and are usually desired for sintering of nanocrystalline (NC) ceramics with fine grains. This paper demonstrates that large α-Al2O3 polycrystalline (PC) NPs with a mean particle size of 62 nm show a similar sintering activity as α-Al2O3 single-crystal (SC) NPs with a mean particle size of 16 nm.α-Al2O3 NC ceramics sintered from the 62 nm α-Al2O3 PC NPs and 16 nm α-Al2O3 SC NPs by two-step sintering exhibit a similar mean grain size of about 75 nm and a similar relative density of about 99.5%. It may be because the 62 nm α-Al2O3 PC NPs and 16 nm α-Al2O3 SC NPs have a similar mean grain size of about 19 nm. These results imply that NC ceramics with fine grains may be sintered from large PC NPs with fine grain sizes.

α-Al2O3 nanoparticles separated by fractionated coagulation still have broad size distributions which limit their wider applications. By adding 20-time mass of large α-Al2O3 (40.5 nm) into α-Al2O3 nanoparticles to be separated in coagulation separation, the average size of separated α-Al2O3 nanoparticles decrease from 6.6 nm without addition of large α-Al2O3 NPs to 4.4 nm, and the size distribution changes from 3–10 nm without addition of large α-Al2O3 NPs to 3–6 nm. With increasing amount of large α-Al2O3 NPs added, separated α-Al2O3 NPs exhibit smaller average sizes and narrower size distribution widths at the same separation concentrations. This approach may be applied to narrow size distribution widths in large-scale size-selective separations of other nanoparticles.

Systemic symmetry is introduced into our work to investigate the symmetries of different ZnO nanocrystals. Result shows that systemic symmetries obey the law of spontaneous symmetry breaking during the formation of ZnO nanocrystals. A unitary formation mechanism of ZnO nanocrystals is proposed accordingly. Our results provide new insight into both crystallization and spontaneous symmetry breaking at meso-scale.

A novel, facile, green and template-free approach was developed for the fabrication of amorphous zinc citrate yolk–shell microspheres and crystalline ZnO yolk–shell nanospheres. In this approach, the amorphous zinc citrate yolk–shell microspheres were prepared through a single chemical reaction at low temperature (90 °C) and with room temperature ageing. The zinc citrate yolk–shell microspheres have an average size of about 1.25 μm. The average diameter of the inner cores and the average thickness of the outer shells are 500 nm and 150 nm, respectively. The effect of ageing time on the morphology of the zinc citrate microstructures was analysed. As the ageing time increases from 0 to 12 h, the zinc citrate microstructure transforms from a solid microsphere through a yolk–shell microsphere to a hollow microsphere. The ZnO solid nanospheres, yolk–shell nanospheres and hollow nanospheres can be prepared via the perfect morphology inheritance of the zinc citrate solid microspheres, yolk–shell microspheres and hollow microspheres, by calcination at 600 °C for 2 h. The ZnO yolk–shell nanospheres show the largest visible emission and the highest photocatalytic activity.