Fe–Cr–Mo–(Y,Ln)–C–B bulk metallic glasses (Ln are lanthanides) with maximum diameter thicknesses reaching 12 mm have been obtained by casting. The high glass formability is attained despite a low reduced glass transition temperature of 0.58. The inclusion of Y/Ln is motivated by the idea that elements with large atomic sizes can destabilize the competing crystalline phase, enabling the amorphous phase to be formed. It is found that the role of Y/Ln as a fluxing agent is relatively small in terms of glass formability enhancement. The obtained bulk metallic glasses are non-ferromagnetic and exhibit high elastic moduli of approximately 180–200 GPa and microhardness of approximately 13 GPa.

Effects of yttrium doping on the thermoelectric properties of Hf 0.6 Zr 0.4 NiSn 0.98 Sb 0.02 half-Heusler alloys By substituting Sn for Sb, the potential of stable ͑Zr,Hf͒Co͑Sb,Sn͒ half-Heusler phases, as p-type thermoelectric materials, for high-temperature power generation has been examined. Sn concentration as much as ϳ20% -30% is required to realize high power factor values. Substitution of heavier Hf, which reduces the thermal conductivity ͑͒ via mass fluctuation scattering, nonetheless maintains high mobility. As a result, the thermoelectric figure of merit ZT, for these not-yet-optimized materials, which we found to be ZT = 0.5 at 1000 K ͑measured͒ and ZT = 0.6 at 1100 K ͑extrapolated͒, surpasses the industry benchmark for a p-type material set by SiGe alloys.

Unlike semiconducting TiCoSb, ZrCoSb and HfCoSb half-Heusler phases are semimetallic below room temperature and exhibit small Seebeck coefficients of ∼−10 μV/K at 300 K. However, upon substituting (doping) the Co and Sb sites with Pt and Sn, respectively, much larger thermopowers (S) are obtained. For ZrCoSb, S reaches −110 and +130 μV/K while resistivity ρ decreases from ∼5×104 μΩ cm in the undoped phase to 1–2×103 μΩ cm in the substituted phases at 300 K. The lowest thermal conductivity obtained in the substituted alloys is ∼3.0 W/m K at 300 K, which is among the lowest reported for this class of structural phases. There are indications that the thermoelectric properties have not been optimized in these multinary alloys.

Half-Heusler alloys ͑MgAgAs type͒ with the general formula MNiSn where M is a group IV transition metal ͑Hf, Zr, or Ti͒ are currently under investigation for potential thermoelectric materials. These materials exhibit a high negative thermopower (Ϫ40 to Ϫ250 V/K) and low electrical resistivity values ͑0.1-8 m⍀ cm͒ both of which are necessary for a potential thermoelectric material. Results are presented in this letter regarding the effect of Sb doping on the Sn site (TiNiSn 1Ϫx Sb x). The Sb doping leads to a relatively large power factor of ͑0.2-1.0͒ W/m K at room temperature for small concentrations of Sb. These values are comparable to that of Bi 2 Te 3 alloys, which are the current state-of-the-art thermoelectric materials. The power factor is much larger at TϷ650 K where it is over 4 W/m K making these materials very attractive for potential power generation considerations.

MnO 3 show insulator-metal transitions on the passage of small electrical currents. That such an electric-field-induced transition occurs even in Y 0.5 Ca 0.5 MnO 3 where the charge-ordered state is not affected by magnetic fields is noteworthy. The transition is attributed to the depinning of the randomly pinned charge solid. These materials also exhibit an interesting memory effect probably due to the randomness of the strength as well as the position of the pinning centers.