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This study investigates rare earth RE3TaO7 ceramics and shows that these materials may be optimal for thermal barrier coatings. ZrO2-Sm3TaO7 ceramics were prepared through a solid-state reaction. X-ray diffusion and structural refinement revealed a phase structure with an ordered orthorhombic phase for the Ccmm space group. The degree of structural disorder increased with increasing ZrO2 content. Gaussian function fitting of the oxygen 1s X-ray photoelectron spectra showed that the Sm3+ and Ta5+ ions were replaced by Zr4+ ions. At high temperatures, 8 mol% ZrO2-Sm3TaO7 has a high thermal expansion coefficient (10.9 × 10−6 K−1). The thermal conductivities of ZrO2-Sm3TaO7 (1.17 − 1.75 W·m−1 K−1) are lower than those of 7–8 wt.% yttria-stabilized zirconia, while those of 2% ZrO2-Sm3TaO7 are the lowest. The oxygen vacancies maintain the charge in equilibrium and enhance phonon scattering while decreasing the thermal conductivity. These results indicate that Sm3TaO7 can be used as a TBC.

In this paper, Ag3Sn nanoparticles were prepared by chemical method and added into SAC305 solder in different proportions to explore the effects of the Ag3Sn on the wettability, melting performance, metallographic structure, and mechanical property of the solder. The results show that a small amount of Ag3Sn nanoparticles were able to reduce the wetting time, increase the maximum wetting force, and expand the spreading area. The melting performance was also improved. Ag3Sn nanoparticles were also found to significantly refine the solder structure in the metallographical. The best comprehensive performance was achieved with the addition of 0.5% Ag3Sn nanoparticles. These Ag3Sn nanoparticles effectively improved the morphology of the IMC at the interface and effectively reduced the thickness of the IMC layer. The addition of nano Ag3Sn increased the diffusion activation energy and stabilized the interface. Moreover, the growth of the IMC layer was inhibited by 0.5% Ag3Sn, as indicated by aging results. The addition of Ag3Sn nanoparticles increases the tensile strength and Vickers hardness of the solder joint. When the amount of Ag3Sn nanoparticles was 0.5 wt%, the tensile strength reached the maximum of 17.45 MPa. The microhardness value of the solder is greatly increased, which reaches 311 HV. Finite element simulation showed that the service life of the solder was prolonged by adding the appropriate amount of Ag3Sn nanoparticles. The paper demonstrates a method of “nano” solder paste preparation. Results show that the addition of Ag3Sn nanoparticles plays an important role in the interfacial reaction and mechanical properties between the SAC solder and Cu substrate.

HfO2–Sm3TaO7 ceramics are prepared through a solid-state reaction method. The X-ray diffraction and structural refinement show that the phase structures of HfO2–Sm3TaO7 ceramics are an ordered orthorhombic phase and the space groups are belonging to Ccmm. The degree of the structural disorder increases with increasing HfO2 content. The solid solution mechanism reveals that Hf4+ exists in the form of interstitial ions that cause crystal expansion when the doping content is less than 4 mol%. When the doping concentration of HfO2 ≥ 4 mol%, the Hf4+ ions can substitute an equal number of Sm3+ and Ta5+ ions. The phase transition of Sm3TaO7 ceramics is removed with increasing HfO2 content, and the 8 mol% HfO2–Sm3TaO7 ceramics have a high thermal expansion coefficient of 10.2 × 10−6 K−1 at 1200 °C. The 2 mol% HfO2–Sm3TaO7 ceramics have the lowest thermal conductivity (1.03 W/m K at 900 °C), which is lower than previous research of the 7–8 YSZ. The outstanding thermophysical properties of HfO2–Sm3TaO7 ceramics indicate that they are potential thermal-barrier coating materials.

SmTaO4 ceramics have excellent high-temperature phase stabilities and mechanical properties and show great potential for use as next-generation thermal barrier coating (TBC) materials. CeO2–SmTaO4 ceramics are prepared via high-temperature solid–state reaction. It retains a single monoclinic phase structure. Ce4+ was reduced to Ce3+ by high-temperature deoxidation, and the Ce3+ ions substitute for an equal number of Sm3+ ions. The CeO2–SmTaO4 ceramics had lower thermal conductivities [1.09–2.75 W/(m K)] than yttria-stabilized zirconia (YSZ) [2.1–2.7 W/(m K)] at 100–800 °C, which decreased dramatically with increasing temperature. SmTaO4 doped with 2% CeO2 had lower thermal conductivity [1.09 W/(m K), 800 °C] than SmTaO4 [1.42 W/(m K), 800 °C] and 2% ZrO2-doped SmTaO4 ceramics [1.22 W/(m K), 800 °C]. The low thermal conductivity is attributed to Ce3+ substitution for an equal number of Sm3+ ions, and because Ce3+ ions are the strongest phonon scattering centers, they can decrease the phonon mean free path effectively. The thermal expansion coefficient of 8% CeO2–SmTaO4 ceramics is approximately 10.3 × 10−6 K−1 at 1200 °C, which is slightly higher than that of both YSZ (10.0 × 10−6 K−1) and SmTaO4 (9.58 × 10−6 K−1). The outstanding thermophysical properties indicate that CeO2–SmTaO4 ceramics are potential TBC materials.

Heat dissipation is a critical issue in high-performance electronics, which needs to be solved, and an electronic paste is a good choice to solve this issue. In this paper, silver nanoparticles/multi-walled carbon nanotube (Ag-NPs/MWCNT) composites were prepared by the chemical process for the modification of electronic pastes. The micromorphology and spectral analysis of the as-prepared Ag-NPs/MWCNT composites indicated that Ag-NPs were uniformly distributed on the MWCNT surfaces with high distribution densities; the average size of Ag-NPs was estimated to be 8.29 nm. The as-obtained Ag-NPs/MWCNT composites were then added to a silver-epoxy paste. Field emission scanning electron microscopy (FESEM), thermogravimetry (TG) and thermal conductivity analyses suggested the incorporation of Ag-NPs/MWCNT composites in the silver-epoxy paste; Ag flakes were better connected by Ag-NPs/MWCNTs, which improved the thermal conductivity of the paste from 0.73 to 0.96 W m−1 K−1. However, more weight loss was observed when Ag-NPs/MWCNTs were incorporated in the silver-epoxy paste. Overall, the addition of Ag-NPs/MWCNTs into the silver-epoxy paste increased the thermal conductivity, which can be applied to high-performance electronics.

Direct current (DC) magnetron sputtering was employed to prepare Cu 2 ZnSnS 4 (CZTS) thin films on soda-lime glass substrates from a ceramic quaternary CZTS target. The influences of DC power, substrate temperature and sulfurization temperature on the composition, crystal structure, surface morphology as well as the optical properties of the films were investigated. Crystalline Cu-poor and Sn-rich kesterite CZTS films were obtained directly from sputtering at a median power, above and below which films were both amorphous. While the film composition remained relatively unchanged with the substrate temperature up to 200 °C, increase of Sn content and decrease of Cu content were observed when the temperature further increased. Sputtering yield, atomic loss due to sublimation as well as the effects of operation conditions were used to explain such compositional change. A secondary phase, less uniform morphology as well as an increased band gap were observed simultaneously for these sputtered films with high Sn content. Sulfurization was carried out to further improve the crystallinity and optical properties of the sputtered CZTS films. An optimal sulfurization temperature of 550 °C was observed, where the film presented a pure CZTS phase, a maximum absorption coefficient (>10 4 cm −1 ) and a theoretic bandgap (1.55 eV).

The HfO2-SmTaO4 ceramics were prepared by solid state reaction at 1700 ℃. The XRD shows that HfO2-SmTaO4 ceramics belong to the monoclinic phase (the space group: I12/ (5)). The HfO2-SmTaO4 ceramics doped with 2 % and 4 % mol have a second phase, which is inferred to as Sm0.33TaO7. The solid solution mechanism of HfO2-SmTaO4 ceramics appears to be the replacement of Sm3+ ions with Hf4+ ions. The HfO2-SmTaO4 ceramics have a lower thermal conductivity (1.50 W m−1 K−1 at 800 ℃) than 7–8-YSZ, with a minimum nearly 30 % lower than YSZ. The low thermal conductivity is attributed to the substitution of Sm3+ ions with an equal number of Hf4+ ions; the resulting oxygen vacancy and point defect enhances phonon scattering, reducing the thermal conductivity of HfO2-SmTaO4 ceramics. The thermal conductivity decreases as the doping of the HfO2 is increased, and the experimental and calculated values tend to be similar. The outstanding thermophysical properties indicate that HfO2-SmTaO4 ceramics are potential TBCs.

The influence of doping with Ge on the nonlinear coefficient α and the breakdown electric field E B of TiO 2 –Ta 2 O 5 –CaCO 3 varistor ceramics was investigated. In this study, TiO 2 –Ta 2 O 5 –CaCO 3 varistor ceramics added with Ge was successfully prepared using the traditional method of ball milling–molding–sintering. The electrical performance, including the nonlinear coefficient α , the breakdown electric field E B , and the leakage current J L , are tested using a varistor direct current parameter instrument. The average barrier height Φ B of each sample is calculated using the relevant formula. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and scanning transmission electronic microscopy analyses demonstrated that Ge doping notably changed the microstructure of TiO 2 –Ta 2 O 5 –CaCO 3 ceramics, thereby increasing α and decreasing E B . When the doping contents of Ta 2 O 5 and CaCO 3 were 0.2 and 0.4 mol%, respectively, the optimum doping content of 0.9 mol% Ge exhibited high α (10.2), low E B (14.1 V mm −1 ), and high Φ B (0.95 eV). These results are superior to previous findings. In addition, Ge as sintering aid reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1300 °C for the TiO 2 –Ta 2 O 5 –CaCO 3 ceramics doped with Ge.

Due to the high conductivity and stability of silver, silver ink has been widely used in the field of printed electronics. However, since mechanical strain would cause the contact between key particles to be broken. Recently, higher requirements have been put on the bending resistance of silver paste. In this experiment, by preparing Ag NPs: Ag Flakes composite materials of 20:80 and 30:70 respectively, a new method for preparing stable modified flake silver powder is proposed, and the attachment and growth methods of Ag NPs reduced on micron flake silver powder is discussed. Flake silver powder, dispersant and reducing agent are added to the silver-ammonia complex, and the nano-silver particles are reduced on the flake silver powder by controlling the reaction conditions. When Ag+: Ag Flakes in the solution is 30:70, there is a clear interface between the silver particles and the silver flakes, and the size distribution range is between 10 and 100 nm; when Ag+: Ag Flakes is 20:80, the distance between the nano-silver particles and the silver plate crystal plane is about 0.222 nm and 0.260 nm, these spacings represent the (1–12) and (004) planes of Ag, respectively. The reduced silver particles grow on the surface of the silver sheet, the size is about 5 ∼ 60 nm, and form a sheet-point combination of shaped silver powder, which can be used to make conductive silver paste with cost and performance competitiveness. The reaction can be completed at room temperature (5 ∼ 25 °C) and atmospheric pressure (80 ∼ 100 kPa), the operation is simple, the reaction time is short, and it has a positive effect on the commercial production of printable highly conductive silver paste.

The core philosophy of Materials Genome Initiative (MGI) is the transition of the way of new materials design from the traditional “trial-and-error” approach to the in-silico materials design approach which employs intensive computing and material informatics. In June 2011, President Barack Obama launched MGI alongside the Advanced Manufacturing Partnership to help businesses discover, develop and deploy new materials twice as fast. In this paper, the concept of rare and precious genome is presented first, followed by the progress of MGI. After that, we focus on the research status of the rare and precious metals’ MGI including the computational tools, the high-throughput experimental methodologies and the rare and precious metals database. We also introduce the application of MGI in the development of rare and precious metal materials, outline the remaining fundamental challenges and present an outlook on the future of the rare and precious metals’ MGI.

The present study investigated the effect of co-doping with elemental crystal Ge or/and GeO 2 on the TiO 2 –Ta 2 O 5 –BaCO 3 varistor ceramic. Results showed that with the doping content of Ta 2 O 5 and BaCO 3 of 0.3 mol% and 0.2 mol%, respectively, the optimum doping content of 0.4 mol% Ge and 1.2 mol% GeO 2 exhibited the highest α value ( α = 12.1), lower breakdown voltage E B ( E B = 20.8 V mm − 1 ), lesser leakage current J L ( J L = 11.5 μA cm − 2 ), and highest grain boundary barrier Φ B ( Φ B = 0.93 eV). The microstructural analyses indicated that Ge–GeO 2 co-doping notably changed the TiO 2 –Ta 2 O 5 –BaCO 3 ceramic microstructure, increased α , and decreased E B . In addition, Ge and GeO 2 , which function as sintering aids, reduced the sintering temperature caused by the low melting point; the best sintering temperature was 1280 °C for TiO 2 –Ta 2 O 5 –BaCO 3 –Ge–GeO 2 ceramic.

This study investigated the influence of codoping with Ge and GeO2 on the nonlinear coefficient α and the breakdown voltage EB of TiO2–Nb2O5–SrCO3 varistor ceramics. Ge–GeO2 codoping notably changed the microstructure of the TiO2–Nb2O5–SrCO3 ceramics, increased α, and decreased EB. When the doping contents of Nb2O5 and SrCO3 were 0.1 and 0.2 mol%, respectively, the optimum doping content of 0.25 mol% Ge and 0.75 mol% GeO2 exhibited high α (11.6), low EB (13.8 V/mm), and high grain-boundary barrier ΦB (0.96 eV). These results are superior to previous findings. In addition, Ge and GeO2, which function as sintering aids, reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1260°C for the TiO2–Nb2O5–SrCO3 ceramics doped with Ge and GeO2.

Digenite (Cu1.8S) has attracted extensive attention as a candidate for use in thermoelectric applications owing to its low cost and low toxicity, but its thermoelectric (TE) properties are still poor. In this study, Pb doping was used to improve the TE properties of Cu1.8S polycrystalline materials. Pb-doped Cu1.8S was fabricated using mechanical alloying (MA) and the spark plasma sintering (SPS) technique. The effects of Pb doping on the TE properties of Cu1.8S were investigated in detail. The power factor of Cu1.8S was maintained upon the introduction of Pb owing to an improved Seebeck coefficient and slightly reduced electrical conductivity. A maximum TE figure of merit (ZT) value of 0.77 was attained at 773 K for a Pb0.01Cu1.79S sample, which was 1.57 times higher than that of a pristine Cu1.8S sample.

The [Formula: see text] ceramics have excellent high-temperature phase stability and mechanical properties and show great potential for use as next-generation thermal barrier coating (TBC) materials. However, the thermophysical properties of [Formula: see text], especially [Formula: see text]-doped, were not clearly established. The [Formula: see text] ceramics doped with different contents of [Formula: see text] (0%, 2%, 4%, 6%, and 8%) by high-temperature solid-state reaction were studied in this paper. The phase structures and microstructures of the samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and EDS. The thermophysical properties of the samples including specific heat, thermal diffusivity, and thermal conductivity were measured systematically. The results show that [Formula: see text]-doped [Formula: see text] ceramics have a single monoclinic phase, and that [Formula: see text] ion doping does not change the crystal structure. The bandgap of 2% [Formula: see text]-doped [Formula: see text] ceramics was narrow (4.48 eV), indicating that heat is conducted by phonons in ceramics. The [Formula: see text] doped with 2% of [Formula: see text] had lower thermal conductivity [Formula: see text] at [Formula: see text] than [Formula: see text] [Formula: see text] at [Formula: see text]. This indicates that 2% [Formula: see text]-doped [Formula: see text] ceramics have the potential to be employed as TBCs in next-generation gas turbines.

Formation mechanism of secondary phase in (La,Nb) Codoped TiO2 ceramics varistor were investigated. The (La,Nb) Codoped TiO2 ceramics samples were prepared from anatase TiO2, Nb2O5 and La2O3 oxide powders by a traditional solid-state sintering method. Microstructure, chemistry composition, crystal structure, thermal etched groove and micrograph of in (La,Nb) Codoped TiO2 ceramics were by SEM, EDS, AFM and TEM. Formation mechanism of secondary phase were discussed by point defect thermodynamical analysis, grain boundary energy and materials structure measurement.The results show that secondary phase are originated from segregation of point defects NbTi andTiLa at grain boundaries in (La,Nb) Codoped TiO2 ceramics. The driving force of segregation is the elastic strain energy. The segregated ion nucleate at grain surface or grain boundaries interface with higher energy. The nucleation gradually grow to form secondary phase at during high-temperature sintering. The growth of secondary phase is mainly on crystal planes with higher energy to minimize the materials system energy.

Monolithic carbon has been synthesized via a sustainable biomimetic route utilizing intrafibrillar silicified collagen sponge as precursor and morphogenesis template. The mineralized silica in the biohybrid prevents collapse of the carbon during pyrolysis. Upon biosilica removal results show that the carbon monoliths inherit the porous fiber structure of the mother collagen. The carbon nanofiber framework facilitates the construction of a high electrical conductive pathway, while the internal spaces developed among the intertwined fibrillar network and pores within nanofiber walls offer room for sulfur storage. The as-obtained carbon-sulfur cathode exhibits an accessible discharge capacity approaching 800[Formula: see text]mAh g[Formula: see text] in Li–S battery.

An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2−V2O5−Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 mol%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value (α = 12.8), the lowest breakdown voltage V1mA (V1mA = 15.8 V/mm) and the highest grain boundary barrier ΦB (ΦB = 1.48 eV), which is remarkably superior to the TiO2−V2O5−Y2O3 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2−V2O5−Y2O3−Ge−GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties.

Crystal structure, chemical composition and phase transition of second phases in (La,Nb)-Codoped TiO2 varistor ceramics was investigated. SEM, XRD, XPS and EDS were carried out the analytic studies on the microstructure, chemical composition and crystal structure of TiO2 ceramics. The results showed that the second phases existed in (La,Nb) doped TiO2 varistors ceramics. With sintering temperature increasing, second phases will transit from LaNbO4 to LaNbTiO6. Ternary phase diagram of La2O3-Nb2O5-TiO2 was plotted based on binary phase diagram of La2O3-Nb2O5, Nb2O5-TiO2 and La2O3-TiO2. According to the ternary phase diagram, the relative content of second phases in TiO2 ceramics sintered at different temperature was estimated. It is suggested that increasing of both second phases and titanium vacancies V""Ti will result in a higher varistor voltage V1mA and nonlinear coefficient α.