[en] CdS quantum dots (QDs) have been synthesized on a large scale, based on the direct thermolysis of one single-source precursor (Me₄N)₄[S₄Cd₁₀(SPh)₁₆], in hexadecylamine (HDA). Transmission electron microscopy (TEM) observations show that the CdS QDs are well-defined, nearly spherical particles. The clear lattice fringes in high-resolution TEM (HRTEM) images confirm the crystalline nature of the QDs. The broad diffraction in the x-ray diffraction (XRD) pattern and diffuse diffraction rings of the selected-area electron diffraction (SAED) pattern are typical of nanomeric-size particles and indicative of the hexagonal phase of CdS QDs. The absorption spectra confirm quantum confinement of CdS QDs. The synthesis process for CdS QDs was investigated by ultraviolet-visible (UV-vis) absorption spectroscopy. The results demonstrate that the nucleation and growth stages were separated automatically in a homogeneous system

[en] In order to study the effect of Cerium on martensitic transformation and microstructure of Ti_49.3Ni_50.7 alloy, a group of TiNiCe alloys with different content of Ce addition were prepared. The microstructure and the martensitic transformation behavior of TiNiCe ternary alloys were investigated by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that the microstructure of Ti_49.3Ni_50.7 alloy is changed obviously by Ce addition, and there are many Ce-rich phases dispersing in the TiNi matrix. One step martensitic transformation due to B2↔B19' transformation occurs during the cooling and heating processes of the TiNiCe ternary alloys. The phase transformation temperatures increase remarkably when the content of Ce is less than 2 at%. However, when the content of Ce is further increasing, the phase transformation temperatures increase slowly and tend to stable. (author)

[en] CdS nanorods were synthesized on a large scale by thermolyzing a single-source precursor, (Me₄N)₄[S₄Cd₁₀(SPh)₁₆], in a single surfactant system. Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and x-ray powder diffraction (XRD) have been used to characterize the morphology and crystal structure of the sample. The TEM images show that the CdS nanorods are uniform with an aspect ratio of about 9:1. The XRD result demonstrates that the nanorods are in a wurtzite structure. The nanorods exhibit quantum size effects from the optical absorption spectrum. The influence of reaction conditions on the growth of CdS nanorods demonstrates that high precursor concentration and high reaction temperature (>190 deg. C) are favorable for the formation of CdS nanorods.

[en] Highlights: • Mn acts as acceptor dopant in AgSbSe₂ to improve electrical transport properties. • The lattice thermal conductivity is reduced due to enhance of phonon scattering. • The figure of merit is improved by Mn doping. • The efficiency obtained here is of great significance for practical application. -- Abstract: AgSbSe₂ exhibits promising thermoelectric performance due to its original low thermal conductivity. Herein, we first investigate the influence of Mn doping on the thermoelectric transport behavior of AgSbSe₂. The results display that the substitution of Mn²⁺ in the Sb³⁺ sublattice increases the carrier concentration and reduces the lattice thermal conductivity, finally leading to a high ZT value of ∼1.05 at 673 K and ZT_ave of ∼0.63 from 300 to 673 K for AgSb_0.96Mn_0.04Se₂. The efficiency of ∼8.8% obtained here is of great significance for practical application.

[en] Highlights: ► Bifunctional CNTs/Fe₃O₄–ZnO nanohybrids are synthesized by one-pot polyol process. ► The nanohybrids display superparamagnetic behavior. ► The nanohybrids display high photocatalytic activity under UV-light irradiation. ► The nanohybrids are recycled magnetically and maintain high photocatalytic activity. - Abstract: One dimensional bifunctional magnetic-photocatalytic CNTs/Fe₃O₄–ZnO nanohybrids were synthesized by one-pot polyol sequential process. The as synthesized products were characterized by X-ray diffraction, Fourier transform infrared spectrometer, transmission electronic microscope, energy dispersive spectrometer, physical properties measurement system and UV–Vis absorption spectroscopy. The results exhibit the ZnO forms heterogenerously on the surface of CNTs/Fe₃O₄ and the nanohybrids display superparamagnetic behavior at room temperature. Photocatalytic studies verify the as-prepared sample have high photocatalytic activity toward the photodegradation of methyl orange in solution. In addition, the photocatalyst can be recycled using magnetic field and maintain high photocatalytic activity.

[en] Nanocomposite is proved to be an effective method to improve thermoelectric performance. In the present study, graphene is introduced into p-type skutterudite La_0.8Ti_0.1Ga_0.1Fe₃CoSb₁₂ by plasma-enhanced chemical vapor deposition (PECVD) method to form skutterudite/graphene nanocomposites. It is demonstrated that the graphene has no obvious effect on the electrical conductivity of La_0.8Ti_0.1Ga_0.1Fe₃CoSb₁₂, but the Seebeck coefficient is slightly improved at high temperature, thereby leading to high power factor. Furthermore, due to the enhancement of phonon scattering by the graphene, the lattice thermal conductivity is reduced significantly. Ultimately, the maximum zT value of La_0.8Ti_0.1Ga_0.1Fe₃CoSb₁₂/graphene is higher than that of graphene-free alloy and reaches to 1.0 at 723 K. Such an approach raised by us enriches prospects for future practical application. (paper)

[en] The composites based on poly(L-lactide) (PLLA) and two kinds of multi-wall carbon nanotubes (Fe₃O₄/MWCNTs and MWCNTs) were prepared by solution casting. The molecular level interactions, thermal, magnetic, mechanical properties and dispersion of MWCNTs in polymer matrix were investigated by Raman spectroscopy, differential scanning calorimetry (DSC), magnetic property measure system (MPMS), tensile test and scanning electron microscopy (SEM). The results of Raman spectra revealed the doping-type molecular interaction between filler and polymer matrix. Compared to the pure PLLA, the glass transition temperature (T_g) of MWCNTs/PLLA and Fe₃O₄/MWCNTs/PLLA composites increased from 50 to 51 deg. C and from 50 to 58 deg. C, respectively. The Fe₃O₄/MWCNTs/PLLA composite was supermagnetic at room temperature. The Young's modulus, elongation rate at break and tensile strength of Fe₃O₄/MWCNTs/PLLA composite were improved compared to the neat PLLA and MWCNTs/PLLA composite. Fe₃O₄/MWCNTs were finely dispersed in the PLLA matrix. The results present potential applications for the biodegradable Fe₃O₄/MWCNTs/PLLA composite in tissue engineer, biomedicine and bone fixation

[en] DLC films with various bias voltages were deposited on polished NiTi alloys by plasma immersion ion implantation and deposition (PIIID) using graphite as plasma precursor. Microstructure and nano-hardness of the DLC films were characterized by Raman spectroscopy and nano-indentation system, respectively. The electrochemical corrosion behavior of DLC coated and uncoated NiTi alloys is investigated in Hank's solution by means of potentiodynamic polarization tests. The results show that on the one hand the corrosion resistance and surface hardness and elastic modulus of the NiTi alloys are remarkably improved due to the deposition of the DLC films, and on the other hand the sp³/sp² ratio inferred from Raman spectra, hardness, elastic modulus and the corrosion resistance of the DLC films on the NiTi alloys first increase and then decrease with the increase of the bias voltage. It can be concluded that the corrosion resistance of the DLC films is influenced by their microstructure

[en] To achieve the commercial application of high-performance skutterudite (SKD) thermoelectric (TE) devices, breakthroughs in the batch fabrication of TE material and the realization of its stable bonding to the barrier layer are necessary. In this work, the large-scale SKD bulks with excellent TE performance and decent homogeneity are prepared by melt-spinning (MS) combined with a hot pressing process. Then, a modified two-step sintering method is employed to effectively suppress the degree of initial interfacial reaction, resulting in a barrier layer/SKD joint that exhibits low contact resistivity (≈2µΩ·cm${}^2$) and high bonding strength (≈30 MPa) with no significant change after aging at 773 K for 30 days. Encouragingly, the joints welded with Mo${}_{50}$Cu${}_{50}$ electrodes also show high stability under the same aging conditions. Finally, the as-fabricated 8-pair module shows a highly competitive conversion efficiency of 9% under a temperature difference of 580 K. In addition, during a 360 h aging test with hot-side temperature of 773 K, the module shows excellent stability. Overall, this work paves the way for batch fabrication of high-performance SKD using MS and lays a solid foundation for the stable operation of SKD-based modules. (© 2024 Wiley‐VCH GmbH)

[en] Novel dendritic SnO₂ nanostructures were successfully synthesized through thermal evaporation of the mixture of ZnS and Sn powders. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and contact angle (CA) apparatus were used to characterize the crystal structure and wettability of as-synthesized product. The results show that each dendrite-like SnO₂ nanostructures consists of several branches, and each branch possess lengths of several tens to hundreds nanometers. The whole dendrite covers several square micrometers. A possible growth mechanism based on growth condition was proposed to interpret the formation of dendritic SnO₂ nanostructures. The synthesized dendritic SnO₂ nanostructures might be used for fabricating novel sensor nanodevices