Enhanced Thermoelectric Performance of SnTe-Based Materials via Interface Engineering.

Interface engineering has been regarded as an effective strategy to improve thermoelectric (TE) performance by modulating electrical transport and enhancing phonon scattering. Herein, we develop a new interface engineering strategy in SnTe-based TE materials. We first use a one-step solvothermal method to synthesize SnTe powders decorated by Sb2Te3 nanoplates. After subsequent spark plasma sintering, we found that an ion-exchange reaction between the Sb2Te3 and SnTe matrixes happens to result in Sb doping and the formation of SnSb nanoparticles and the recrystallization of the nanograined SnTe at the grain boundaries of the SnTe matrix. Benefitting from this unique engineering, a significantly reduced lattice thermal conductivity of ∼0.64 W m-1 K-1 and a high zT of ∼1.08 (∼100% enhanced) at 873 K are achieved in SnTe-Sb0.06. Such improved TE properties are attributed to the optimized carrier concentration and valence band convergence due to the Sb doping and enhanced phonon scattering by interface engineering at the grain boundaries. This work has demonstrated a facile and effective method to realize high-TE-performance SnTe via interface engineering.

[Effect of bivalent alkaline earth fluorides introduction on thermal stability and spectroscopic properties of Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses].

Transparent Er3+/Tm3+ /Yb3+ co-doped oxyfluorogermanate glasses alone containing MgF2, CaF2, SrF2 or BaF2 and nano-glass-ceramics only containing BaF2 were prepared. The thermal stabilities and the up-conversion emission properties of the samples were investigated. Analyses of absorbance spectra reveal that the UV cutoff band moves slightly to shortwave band with the doping bivalent cation mass increasing. The results show that the emission color can be adjusted by changing the alkaline earth cation species in the glass matrixes, especially as Mg2+ is concerned, and the emission intensity can increase notably by heating the glass containing alkaline-earth fluoride into glass ceramic containing alkaline-earth fluoride nanocrystals or increasing the content of bivalent alkaline earth fluorides.

Effect of Mn-Zn ferrite on apatite-wollastonite glass-ceramic (A-W GC).

Magnetic bioactive glass-ceramics (M GC) were prepared by doping apatite-wollastonite glass-ceramic (A-W GC) with Mn-Zn ferrite. The effect of different contents of Mn-Zn ferrite on the phase structure, magnetic property and bioactivity of A-W GC was investigated. X-ray powder diffraction results showed that A-W GC exhibited apatite, fluorapatite and wollastonite as the main phases. The doping of Mn-Zn ferrite caused the formation of a new phase Zn(0.75)Mn(0.75)Fe(1.5)O(4) in M GC. The amount of this new phase increased with increasing content of Mn-Zn ferrite. Under a magnetic field of 7.96 x 10(5) A m(-1), the saturation magnetization of M GC increased from 4.63 to 9.7 A m(2) kg(-1), but the coercive forces of M GC decreased from 2.39 x 10(4) to 7.56 x 10(3) A m(-1) as the Mn-Zn ferrite content increased from 5% to 20% in the material. The bioactivity of samples was evaluated by soaking in simulated body fluid (SBF). The results showed that the doping of Mn-Zn ferrite decreased the bioactivity of A-W GC dramatically. It took 7 days for an apatite layer to form on the surface of A-W GC, while at least 30 days was needed for an apatite layer forming on the surface of M GC.