We present experimental evidence of enhancement of thermoelectric properties in tellurium (Te) nanoparticle-embedded bismuth antimony telluride (BiSbTe) alloys. Bi0.5Sb1.5Te3 films with a high density of Te particles of 10–20 nm size were prepared by growth of alternating multilayers of ultrathin Te and Bi0.5Sb1.5Te3. As the amount of Te nanoinclusions increased up to ∼15%, the Seebeck coefficient and thermoelectric power factor were increased. Based on the concept of band bending at heterointerfaces as a carrier energy filter, the energy relaxation calculation was made to confirm that the Te nanoinclusions result in a carrier energy filtering effect in p-type bismuth antimony telluride. In addition, thermal conductivities were reduced in the Te-embedded samples, permitting possible further enhancement of the thermoelectric figure of merit. The advantages of Te nanoinclusions in p-type Bi0.5Sb1.5Te3alloys on thermoelectric performance are experimentally realized by both electron- and phonon scattering.

(Zr, Hf)NiSn-based half-Heusler alloys with refined grains were prepared by melt spinning and spark plasma sintering. The grain size of the melt-spun (MS) thin ribbons varied from ∼500 nm to ∼3 μm. X-ray diffraction analysis showed that single phased alloys were obtained. Nanoscale precipitates dispersed in the matrix could be observed in both the MS ribbons and sintered bulk samples, which increased the carrier concentration and electrical conductivity. The lattice thermal conductivity decreased by more than 20% below 100 K and 5–20% from 200 to 1000 K, compared with the levitation melted counterparts, due to the refined grain sizes. The maximum dimensionless figure of merit ZT value reached ∼0.9 for the MS Hf0.6Zr0.4NiSn0.98Sb0.02sample.

Structure and phase transitions of (1 − y)((1 − x)Bi1/2Na1/2TiO3–xBi1/2K1/2TiO3)–yK0.5Na0.5NbO3 (x; y) piezoceramics (0.1 ≤ x ≤ 0.4; 0 ≤ y ≤ 0.05) were investigated by transmission electron microscopy, neutron diffraction, temperature-dependent x-ray diffraction, and Raman spectroscopy. The local crystallographic structure at room temperature (RT) does not change by adding K0.5Na0.5NbO3 to Bi1/2Na1/2TiO3–xBi1/2K1/2TiO3 for x = 0.2 and 0.4. The average crystal structure and microstructure on the other hand develop from mainly long-range polar order with ferroelectric domains to short-range order with polar nanoregions displaying a more pronounced relaxor character. The (0.1; 0) and (0.1; 0.02) compositions exhibit monoclinic Cc space group symmetry, which transform into Cc + P4bm at 185 and 130 °C, respectively. This high temperature phase is stable at RT for the morphotropic phase boundary compositions of (0.1; 0.05) and all compositions with x = 0.2. For the compositions of (0.1; 0) and (0.1; 0.02), local structural changes on heating are evidenced by Raman; for all other compositions, changes in the long-range average crystal structure were observed.

Solid solutions of Ba1−xPbxZrO3 (0 ≤ x ≤ 0.75) have been synthesized successfully by polymeric citrate precursor method for the first time. The solid solutions were characterized by powder x-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and surface area studies. XRD studies reveal the monophasic nature of these highly crystalline nanoparticles (except few impurity of ZrO2 in PbZrO3). Lattice parameter of Ba1−xPbxZrO3 (0.20 ≤ x ≤ 0.75) decreases with increasing the Pb content. Dielectric properties of these nanoparticles were investigated as a function of frequency and temperature. The dielectric constant for x = 0.15 showed a maximum value of 75.5.

High permittivity antimony-doped tin oxide (ATO)/polyimide (PI) composite films consisting of narrow size distribution ATO fillers prepared by inverse microemulsion method and PI host are synthesized by in situ polymerization. The microstructure and thermal stability of composite films are characterized by scanning electron microscopy and thermal gravimetric analyses, respectively. Dielectric properties of composite films with different concentrations of ATO particles of variable size are investigated in the frequency range of 102 to 2.5 × 106 Hz. The hydrophilic surface of ATO is not helpful of tight connection between the filler and host. The addition of ATO contributes slight increase of the thermal stability. However, the permittivity of composite films can be remarkably increased due to Maxwell–Wagner–Sillars polarization as well as a large number of tiny capacitors formed by ATO particles with narrow distribution and small size. The dielectric constant behavior of composite films fits well to the usual percolation theory.

The phase evolution, nucleation, and sintered ceramics of barium titanate (BaTiO3, BT) powder prepared by solid-state synthesis with an ultrafine starting material (27 m2/g of BaCO3 and 190 m2/g of TiO2) were investigated in this study. Surface diffusion between BaCO3 and TiO2 was observed at a relatively low temperature of 400 °C by transmission electron microscopy. Rapid nucleation of the BT and cubic BT phases was observed at 500 °C by x-ray diffraction. The derivative thermogravimetry curve clearly shows a single step of BT formation at 600 °C. In short, pure BT particles with an average particle size of 250 nm and high tetragonality were prepared by solid-state synthesis, which produced X7R ceramics with high dielectric permittivity, high insulation resistance, and a clear core–shell structure.

We report herein the crystal growth of ZnO nanoparticles by the foam fractionation method. In this study, the vertical column height of the foam was fixed and the velocity of the sparging air was varied, and the effect of foam flow rate on the synthesis of ZnO was investigated. The obtained ZnO consisted of aggregated platelets and had differing ultraviolet absorbances. The as-synthesized ZnO was hydrophobic because of the interaction between the anionic head groups of sodium dodecyl sulfate (SDS) and the ZnO under the precipitation conditions. The long chain of the SDS molecule was the cause of hydrophobicity. The contact angle of water was in the range of 95–105° for the obtained ZnO/SDS surface. The photocatalytic degradation efficiency of the as-synthesized (ZnO/SDS) and the calcined ZnO was investigated for methylene blue, and the calcined ZnO retained its activity even after three recycles.

Vanadium (V)–aluminum (Al)–carbon (C) thin films were deposited on Al2O3$(11\mathop 2\limits^ - 0)$ substrates at 500 °C by direct current magnetron sputtering using a powder metallurgical composite target with 2:1:1 MAX phase stoichiometry. Transmission electron microscopy (TEM) and x-ray diffraction results suggest that a hexagonal Al-containing vanadium carbide solid solution (V,Al)2Cx was formed. The films exhibited a strong basal plane texture. The lattice parameter of the hexagonal solid solution was dependent on the annealing temperature: the c lattice parameter decreased by 3.45% after annealing for 1 h at 750 °C compared to the as-deposited film. Based on the comparison between experimental and theoretical lattice parameter data, it is reasonable to assume that this annealing-induced change in lattice parameter is a consequence of atomic ordering. Meanwhile, the formation of V2AlC MAX phase was observed at 650 °C and phase-pure V2AlC was obtained at 850 °C. TEM images support the notion that V2AlC forms by nucleation and growth.

Normal spectral intensities of resistively heated preoxidized ZrB2–30 mol% SiC–6 mol% B4C specimens were measured in the 1–6 μm and ∼1100–1500 °C ranges. Using Wein’s displacement law, the temperatures of these specimens were determined, in turn permitting calculation of normal spectral emittances using Planck’s law. Spectral emittance data were affected by absorption/emission of H2O/CO2 gases; total emittances were determined from the averages of data in spectral ranges devoid of gaseous interference. Total emittances decreased from 1.0 at 1100 °C to 0.8 at 1500 °C. This trend is consistent with the behavior expected of a dielectric coating.

Nd-doped LaVO4 crystals with the concentration up to 0.94 at.% were successfully grown by the Czochralski method. X-ray powder diffraction measurement reveals that this crystal belongs to a monoclinic space group P21/n. Refractive indices of Nd:LaVO4 have been measured with two right angle prisms for the first time to our knowledge and show that they are anisotropic. Its absorption and fluorescence spectra are also investigated. With the Judd–Ofelt theory, the optical parameters calculated are Ω2 = 2.142 × 10−20 cm2, Ω4 = 3.704 × 10−20 cm2, and Ω6 = 2.948 × 10−20 cm2. By these parameters, the absorption oscillator strengths, line strengths, transition probabilities, fluorescence branch ratios, radiative lifetime, and integrated emission cross section are also derived and compared with familiar vanadates, which show that Nd:LaVO4 is a atypical material and has potential applications in the lasers, especially in the pulsed lasers.

Yellow-emitting long afterglow phosphors Sr3−xSiO5, xMF2: Eu2+, Dy3+ (0 ≤ x ≤ 0.15, M: Ba, Sr, Ca) have been prepared by high-temperature solid-state reaction method followed with rapid cooling process. Photoluminescence measurement reveals that the main emission of the phosphors locates at 575 nm, corresponding to the 4f65d1–4f7 transition of Eu2+. The introduction of alkaline earth metal fluoride effectively enhances the luminescence intensity and prolongs the afterglow time. Especially, the afterglow of the Sr2.95SiO5, 0.05BaF2: Eu2+, Dy3+ phosphor can last for 12 h. Thermal luminescence measurement shows that the trap density of Sr3SiO5: Eu2+, Dy3+ phosphor can be adjusted by adding different alkaline earth metal fluorides, which offers a feasible way to improve the afterglow properties of silicate phosphors.

A cosolvent spray pyrolysis process was used for the generation of micrometer-sized pure copper particles. Ethylene glycol (EG) and ethanol (ET) were selected as cosolvents, and their effects on particle morphology and composition were systematically investigated. Experimental results showed that oxide-free copper particles could be generated at temperatures greater than 400 °C with either cosolvent. Hollow particles with cracks were generated with ET at temperatures from 400 to 1000 °C, whereas EG promoted the formation of porous particles at temperatures up to 600 °C and hollow shell particles with smooth surfaces at 875 and 1000 °C. Results from short residence time experiments indicated that, during the generation process, lamellar and fragment-like copper hydroxy nitrate [Cu2(OH)3NO3] precipitated when EG and ET were used respectively. Cu2(OH)3NO3 then decomposed to cupric oxide (CuO) and cuprous oxide (Cu2O). Finally the oxides were reduced to copper (Cu) in the reducing atmosphere created by EG and ET.

A new technique based on the detection of the amplitude of the second harmonic was described in a previous paper. To compute the elastic modulus and the hardness of materials, the technique uses only the derivative of the contact radius with respect to the indentation depth. For this reason, this method is applicable only to homogeneous materials. In this paper, the method is extended to any materials with constant Young modulus. The indentation depth value is not needed at all, thus eliminating uncertainties related to the displacement measurement, which are very influent at small penetration depths. Furthermore, we also explain how to compute the indentation depth from the detection of the amplitude of the second harmonic. This new measurement technique was tested on three samples: fused silica, Poly(methyl methacrylate) (PMMA), and calcite, which is expected to exhibit indentation size effect. The obtained results show that mechanical properties and the indentation depth can be determined with good accuracy for penetration depths between 25 and 100 nm using this method.

Positron annihilation lifetime measurements are performed for sol–gel-derived 70 mol% SiO2–30 mol% CaO bioactive glass. Strong positronium formation processes are shown to be an inherent feature for these kinds of materials. Observed orthopositronium (o-Ps) lifetimes show a three-modal distribution with lifetime values weighed at ∼2, ∼18, and ∼70 ns. The exposure of the investigated sol–gel-derived bioactive glasses to water vapor significantly modifies o-Ps lifetime distribution due to the penetration of water molecules into the nanopores, indicating high ratio of their interconnectivity. Classic Tao–Eldrup equation is used to relate the o-Ps lifetimes with the size of nanopores, whose distribution is verified by nitrogen adsorption porosimetry.

Backscattered electron microscopy provides gray-level contrast resulting from variations in atomic composition. Through the use of reference materials, quantitative backscattered electron (qBSE) imaging can be used to measure the mineral content of mineralized tissues at submicron resolution. We have developed novel tunable reference materials that can be adjusted for analysis of an individual tissue or a wide range of tissues with variable atomic density. As an alternative to conventional metallic reference materials, these amorphous materials maintain long-term stability and possess no long-range order that may induce channeling contrast. Using these reference materials, we characterized the mineral content of a broad range of mineralized tissues from immature mouse femur to whale bulla. Mineral volume fraction correlated to more traditional measurements of mineral content with microcomputed tomography and ashing techniques. Further, we demonstrate the advantage of location-matched measurements of nanomechanical properties and qBSE mineral content.