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Spinel ferrite MFe2O4 (M = Mn, Fe, Co, Ni, and Zn) nanoparticles, coordinated with oleylamine, oleic acid, and trioctylphosphine oxide, were effectively synthesized by the microwave-assisted rapid ...

Thermoelectric (TE) materials have consistently gained momentum for use in waste heat utilization technology. Recently, we fabricated a Cu3AlSnS5 (CATS) nanobulk by pelletizing chemically synthesiz...

Among the promising waste heat harvesting technologies, thermoelectric materials and devices have attracted considerable interest in recent decades because they offer a promising route to convert waste heat into electrical power. The Cu2Sn1–xZnxS3 system consists of green and abundant elements and exhibits modest thermoelectric performance at a relatively low temperature range. However, the thermoelectric figure of merit, ZT, of Cu2Sn1–xZnxS3 is still too low for practical applications. This study encompasses the bottom-up wet chemical synthesis of Cu2Sn1–xZnxS3 nanoparticles with varying Zn compositions. By blending Cu2Sn0.85Zn0.15S3 and Cu2Sn0.9Zn0.1S3 nanoparticles in a weight fraction of 9:1 to make a nanobulk material, we could achieve a maximum ZT value of 0.64 at 670 K, which is 1.7 and 1.9 times higher than the ZT values of the pristine Cu2Sn0.85Zn0.15S3 and Cu2Sn0.9Zn0.1S3 nanobulk materials, respectively.

Developments in subcellular fractionation strategies have provided the means to analyze the protein and lipid composition of organelles by proteomics. Here, we developed ultrasmall magnetic-plasmonic hybrid nanobeads and applied them to the isolation of autophagosomes by applying a magnetic field. The beads were chemically synthesized and comprised an Ag/FeCo/Ag core/shell/shell structure with a mean diameter of 15 nm. The Ag core and the FeCo shell conferred imaging and magnetic separation capabilities, respectively. The nanobeads were transfected into mammalian cells by lipofection. Thirty minutes after lipofection, the nanobeads colocalized with Vps26 and subsequently with LC3. Cell lysates were prepared at the appropriate time points and were subjected to magnetic separation. The separated fraction contained LC3-II, transferrin receptor, and LAMP2, but not LC3-I, suggesting that autophagosomes engulfing endosomal origin had been isolated. The magnetic separation process was completed in less than 30 min, providing a rapid method for isolation of autophagosomes. The present organelle isolation technique using the hybrid nanobeads with imaging and magnetic separation capabilities is highly promising for isolation of other types of organelles such as endosomes and endosome-related organelles.

Here, we report a method for facile gram-scale synthesis of tetrahedrite (Cu12Sb4S13) nanoparticles (NPs) with high quality and good reproducibility. The obtained NPs had a well-defined tetrahedral shape with a mean edge length of ∼70 nm. We sintered the NPs by the hot press technique to fabricate a nanostructured pellet for thermoelectric measurements. The figure of merit (ZT) value of the pellet was 0.52 at 675 K, which was comparable with the ZT value of the non-nanostructured counterpart.

Magnetic–plasmonic hybrid nanoparticles have gained immense attraction as capable agents for concurrent magnetic and plasmonic hyperthermia in next-generation adjuvant therapies of cancer. There has been a dramatic expansion in the development of novel hybrid nanoparticles with improved hyperthermal properties in the last two decades. In this chapter, synthetic protocols, structures, and physical properties of different types of magnetic–plasmonic hybrid nanoparticles are outlined. Several examples of hyperthermia using magnetic and/or plasmonic particles are described early in the chapter. Later, various synthetic methods of creating magnetic–plasmonic hybrid nanoparticles are described, followed by descriptions of their structural and functional characteristics. This chapter will be helpful for those who are considering fabricating magnetic–plasmonic hybrid nanoparticles for bio-applications.

Recently we developed magnetic–plasmonic Ag/FeCo/Ag core/shell/shell nanoparticles for the purpose of biological applications. In these heterostructured nanoparticles, exchange bias is observed as a result of the formation of an interface between ferromagnetic FeCo and antiferromagnetic Co x Fe 1− x O due to the partial oxidation of the FeCo intermediate shell. In this study we thoroughly characterized the surface oxide layer of the FeCo shell by XPS, XRD and SQUID magnetometer.

In this paper, temperature dependence of breakdown electrical field (Ebd) and time-to-failure (TTF) in AC TDDB for thick insulator film (300 nm) deposited by plasma process are discussed. In SiO2 film deposited using TEOS and O2 gases, increase of both Ebd and TTF beyond 100 °C is observed. On the other hand, in the SiO2 film and SiN film involving nitrogen, both Ebd and TTF decrease with increasing temperature. In order to explain this difference, we focused on the type of conductivity and introduced de-trapped effect by thermal energy. And we proposed a simple model to explain the temperature dependence of those AC TDDB results. In the SiO2 film deposited using TEOS and O2, the temperature dependence of number of trapped carrier is smaller because the conductivity type is the FN tunnelling, while the number of de-trapped carrier significantly increases with temperature and the TTF beyond 100 °C becomes longer. In these films involving nitrogen, the de-trapped effect is negligible because the number of trapped carrier exponentially increases with temperature because of Poole-Frenkel conductivity.

Paracostibite (CoSbS) is a promising candidate for n-type thermoelectric materials. In this study, a nanostructured CoSbS pellet was fabricated using chemically synthesized Co–Sb–S nanoparticles as building blocks. The CoSbS pellet showed the highest electrical conductivity (σ = 141 S/cm at 661 K) and lowest thermal conductivity [κ ≅ 2 W/(m K)] among the reported CoSbS. Detailed analysis of the electrical transport process in a wide temperature range (3 K–661 K) revealed the existence of a donor level. At a temperature less than 170 K, the resistivity showed Mott variable-range hopping behavior, while the band conduction became dominant as the temperature increased. Nanograins in the pellet significantly enhanced phonon scattering, resulting in suppression of κ. The maximum dimensionless figure of merit value was 0.05 at 661 K, which is comparable with previously reported values for CoSbS TE materials.

The combination of magnetic and plasmonic materials and their nanostructurization have revealed a prominent pathway to develop novel photonic materials for the active control of the light polarization using a magnetic field. Until now, physical growth methods have been the only exploitable approach to prepare these types of nanostructures. Here, we demonstrate the chemical synthesis of magneto-plasmonic core/shell nanocrystals with enhanced magnetic control of optical properties comparable to the best results reported for nanostructure growth by physical methods. Ag/FeCo core/shell nanocrystals were synthesized using a combination of hot injection and polyol approaches, demonstrating that the well-defined structures of both components, their interface and the optimized morphology, where the plasmonic and magnetic components are placed in the core and the shell regions, are responsible for the observed large enhancement of magnetic control of light polarization. Therefore, there is a possibility to develop tunable magneto-optical materials from hybrid magneto-plasmonic structures synthesized by chemical methods.

Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

Combining different properties derived from different materials into a single nanoparticle allows diverse applications in many fields. In terms of plasmonic and magnetic properties, Ag and FeCo are the best candidates due to their optimal physical properties – Ag has the highest scattering cross-section of all plasmonic materials and FeCo has the highest saturation magnetization of all magnetic materials. Recently we have succeeded in synthesizing magnetic–plasmonic hybrid Ag@FeCo@Ag core–shell–shell nanoparticles; however, the formation mechanism of the hybrid nanoparticles was still unclear. In this study, we investigated the formation mechanism of the Ag@FeCo@Ag double shell nanoparticles. Understanding the formation mechanism will help in tuning the physical properties of the Ag@FeCo@Ag nanoparticles and in designing novel heterostructured nanoparticles.

Combining Au and Fe into a single nanoparticle is an attractive way to engineer a system possessing both plasmonic and magnetic properties simultaneously. However, the formation of the AuFe alloy is challenging because of the wide miscibility gap for these elements. In this study, we synthesized AuFePt ternary alloy nanoparticles as an alternative to AuFe alloy nanoparticles, where Pt is used as a mediator that facilitates alloying between Au and Fe in order to form ternary alloy nanoparticles. The relationship among composition, structure, and function is investigated and it was found that at an optimized composition (Au52Fe30Pt18), ternary alloy NPs exhibit both magnetic and plasmonic properties simultaneously. The plasmonic properties are investigated in detail using a theoretical Mie model, and we found that it is governed by the dielectric constant of the resulting materials.

Plasmonic–magnetic dual-functional nanoparticles consisting of a graded structure with plasmonic silver (Ag) and ferromagnetic iron–cobalt–platinum alloy (FeCoPt) components mixed at the atomic level with a composition gradient were chemically synthesized. The surfaces of the nanoparticles were uniformly covered with iron oxide (Fe x O y ). The resulting nanoparticles possessed a graded-core/oxide-shell structure and unique physical properties. In addition, the surfaces of the nanoparticles were biotinylated to enhance their versatility for use in various bioapplications such as bioimaging, biosensing, immunodiagnosis, and hyperthermia.

Uniform Cu2Sn1-xZnxS3 (x = 0–0.2) nanoparticles (NPs) with a characteristic size of about 40 nm were chemically synthesized. The primary crystal phase of the NPs was wurtzite (WZ) with a mean crystalline size of about 20 nm. The NPs were sintered to form nanostructured pellets with different compositions preserving the composition and grain size of the original NPs by the pulse electric current sintering technique. The pellets had a zinc blende (ZB) structure with a residual WZ phase, and the mean crystalline size was found to remain virtually unchanged for all pellets. Among all samples, the pellets of Cu2Sn0.95Zn0.05S3 and Cu2Sn0.85Zn0.15S3 exhibited the highest ZT value (0.37 at 670 K) which is 10 times higher than that of a non-nanostructured Cu2SnS3 bulk crystal thanks to effective phonon scattering by nanograins, the phase-pure ZB crystal structure, and the increase in hole carrier density by Zn doping.

A polarization-sensitive Fourier domain optical coherence tomography (PS-FD-OCT) system is demonstrated. This OCT system is based on a spectral interferometer, does not require mechanical axial scanning, and enables phase information to be used in an OCT image. Owing to this phase information, the system requires only two measurements for determining the Jones matrix images and Muller images of biological samples. This system reveals the birefringence properties of the inner surface of a porcine esophagus.

The evolution of the exchange bias field was investigated in Ag@FeCo@Ag and AgAu@FeCo@AgAu core@shell@shell nanoparticles as a function of aging time. Because of the partial oxidation of the thin (∼2.5-nm thick) ferromagnetic (FM) FeCo intermediate shell to an antiferromagnetic (AFM) Co0.5Fe0.5O phase, exchange bias was clearly observed at the interface between the FM and AFM layers. The exchange bias field monotonically increased with aging time when the ratio between the volumes of the AFM ( vAFM) and FM ( vFM) layers, vAFM/vFM, was less than 2.8. However, the exchange bias field showed an oscillatory behavior with respect to vAFM/vFM, when vAFM/vFM>3.6. This oscillatory behavior probably results from the small interfacial area between the FM and AFM layers, which causes fluctuations of the surplus magnetization in the AFM shell. Using the exchange bias field within the linear regime, it is possible to sensitively estimate the thickness of the AFM layer (i.e., the surface oxide layer).

Ethylenediamine (EDA), and p-phenylenediamine (PA) were intercalated into layered tetratitanate. The reactions were enhanced by the water present in these organics and in the interlayer of titanate. The compositions of the products were (EDA)0.68H2Ti4O9, and (PA)3.12H2Ti4O9. Molecular axes of EDA and PA were estimated respectively parallel and perpendicular to the host titanate interlayer surface. Ethylene glycol and bis(2-hydroxyethyl)terephthalate could not be intercalated.