Molybdenum oxides MoO_x in the composition range 2 ≤ x ≤ 3 were synthesized and compacted by solid state reaction of powdered α-MoO₃ with Mo in the Spark-Plasma Synthesis (SPS) process at temperatures up to 973 K. From six known compounds in the Mo-O system, Mo₁₈O₅₂ (x = 2.889), Mo₁₇O₄₇ (x = 2.760) and γ-Mo₄O₁₁ (x = 2.750) were synthesized as single-phase products despite their narrow composition ranges (≈0.1 at %) with a yield (0.5-1g per synthesis) sufficient for thermoelectric property measurements on polycrystalline bulk material from room temperature to 763 K. For Mo₁₈O₅₂, which appears to be an intrinsic narrow-gap semiconductor (activation energy ≈0.6 eV), exceptionally low thermal conductivity over the full temperature range (0.5 to 0.9 W m^-1K^-1), high p-type Seebeck coefficient at room temperature (+140 µV K^-1) and a p-n-transition at 440 K was found. The phases MoO₂, γ-Mo₄O₁₁ and Mo₁₇O₄₇ show poor metallic conductivity. Highest power factor is achieved by Mo₁₇O₄₇ (30 Wm^-1K^-2 for 440 K ≤ T ≤ 610 K). In γ-Mo₄O₁₁, a hitherto unknown reversible transition is found at 450 K from specific heat measurements.

By applying the melt-centrifugation, porosity and dislocations are introduced in the microstructure of the n-type Zintl phase Mg_3+xSb_1.5Bi_0.49Te_0.01leading to significantly low κ_l (∼ 0.33 W m⁻¹ K⁻¹ at 723 K) and enhanced zT (∼ 1.64 at 723 K).

The solid-state reaction of WO₃ with W was studied in order to clarify the phase formation in the binary system W-O around the composition WO_x (2.50 ≤ x ≤ 3) during spark plasma sintering (SPS). A new phase “WO_2.82” is observed in the range 2.72 ≤ x ≤ 2.90 which might have the composition W₁₂O₃₄. The influence of the composition on the thermoelectric properties was investigated for 2.72 ≤ x ≤ 3. The Seebeck coefficient, electrical conductivity and electronic thermal conductivity are continuously tunable with the oxygen-to-tungsten ratio. The phase formation mainly affects the lattice thermal conductivity κ_lat which is significantly reduced until 700 K for the sample with the composition x = 2.84, which contains the phases W₁₈O₄₉ and “WO_2.82”. In single-phase WO_2.90 and multi-phase WO_x materials (2.90 ≤ x ≤ 3), which contain crystallographic shear plane phases, a similar reduced κ_lat is observed only below 560 K and 550 K, respectively. Therefore, the composition range x < 2.90 in which the pentagonal column structural motif is formed might be more suitable for decreasing the lattice thermal conductivity at high temperatures.

The OER activity of isostructural M₂Pt (M = Al, Ga, In, Sn) compounds is governed by the nature of counterpart element (M), its leaching rate and corresponding change of the Pt electronic state.

New Heusler compounds NiRh ₂ Sb and CuRh ₂ Sb are synthesized in nano-scale and in bulk. The nanoparticles prove to be excellent catalysts for electrochemical water splitting.