Fully filled skutterudites RFe 4 Sb 12 (R ¼ Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb) have been prepared and the high-temperature electrical and thermal transport properties are investigated systematically. Lattice constants of RFe 4 Sb 12 increase almost linearly with increasing the ionic radii of the fillers, while the lattice expansion in filled structure is weakly influenced by the filler valence charge states. Using simple charge counting, the hole concentration in RFe 4 Sb 12 with divalent fillers (R ¼ Ca, Sr, Ba, Eu, and Yb) is much higher than that in RFe 4 Sb 12 with trivalent fillers (R ¼ La, Ce, Pr, and Nd), resulting in relatively high electrical conductivity and low Seebeck coefficient. It is also found that RFe 4 Sb 12 filled skutterudites having similar filler valence charge states exhibit comparable electrical conductivity and Seebeck coefficient, and the behavior of the temperature dependence, thereby leading to comparable power factor values in the temperature range from 300 to 800 K. All RFe 4 Sb 12 samples possess low lattice thermal conductivity. The correlation between the lattice thermal resistivity W L and ionic radii of the fillers is discussed and a good relationship of W L $ (r cage Àr ion ) 3 is observed in lanthanide metal filled skutterudites. CeFe 4 Sb 12 , PrFe 4 Sb 12, and NdFe 4 Sb 12 show the highest thermoelectric figure of merit around 0.87 at 750 K among all the filled skutterudites studied in this work.

Eu 2+ doped Sr 2 Al x Si 5−x N 8−x/3 red phosphors have been synthesized by a solid state reaction method, with the aim of improving their thermal quenching properties. The XRD patterns confirm that Al 3+ can efficiently substitute Si 4+ in the Eu 2+ doped Sr 2 Si 5 N 8 host. The crystal structure is studied by Rietveld refinement, selected-area electron diffraction (SAED) and solid-state NMR analysis. With an increase in x, the emission spectra show no obvious shift and the full width at half maximum (FWHM) increases from 86 to 94.2 nm.Remarkably, the thermal quenching properties are obviously improved as appropriate Al 3+ substituted Si 4+ .The corresponding mechanism is discussed in detail based on the influence of size mismatch and the configurational coordinate model.