The interaction of catechol with chromium(III) oxide (Cr(2)O(3)), manganese dioxide (MnO(2)), iron(III) oxide (Fe(2)O(3)), and titanium dioxide (TiO(2)) was evaluated as a function of pH conditions (pH 3-10) and ionic strength using a combined approach of bulk adsorption, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and dissolution analysis. Adsorption of catechol showed a strong pH-dependent behavior with the metal oxides, remaining constant under acidic-neutral pH (3-7) and increasing under more basic conditions. In situ ATR-FTIR measurements indicate that catechol binds predominately as an outer-sphere complex on MnO(2) and as an inner-sphere complex on Fe(2)O(3), TiO(2), and Cr(2)O(3) substrates. Catechol complexation on Fe(2)O(3), TiO(2), and Cr(2)O(3) promotes dissolution at pH >5, whereas MnO(2) dissolution occurs under acidic and basic conditions (pH 3-10).

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The new layered compound Li(3)Ni(2)BiO(6) has been prepared by a solid-state reaction. It crystallizes in the monoclinic C2/m space group; its lamellar structure is characterized by a honeycomb ordering between Ni(2+) and Bi(5+) within the slabs, while Li(+) ions occupy octahedral sites in the interslab space. Stacking defects weakly alter the XRD pattern. By substitution of half of the nickel ions, the new phases Li(3)NiM'BiO(6) (M' = Mg, Cu, Zn) isostructural with Li(3)Ni(2)BiO(6) have been synthesized under similar conditions. All these compounds demonstrate paramagnetic behavior at high temperature, and Li(3)Ni(2)BiO(6) exhibits an antiferromagnetic ordering at 5.5 K. By topotactic molten salt ionic exchange, the new delafossite compound Ag(3)Ni(2)BiO(6) has been also obtained and characterized.

The development of oxides with high figure of merit, ZT, at modest temperatures (∼300−500 °C) is desirable for ceramic-based thermoelectric generator technology. Although ZT is a compound metric with contributions from thermal conductivity (κ), Seebeck coefficient (S), and electrical conductivity (σ), it has been empirically demonstrated that the key to developing thermoelectric n-type oxides is to optimize σ of the ceramic to ∼1000 S/cm at the operating temperature. Titanate-based perovskites are a popular choice for the development of n-type oxide ceramics; however, the levels of σ required cannot be achieved without control of the ceramic quality, significant reduction of the ceramic in low P(O 2 ) atmosphere (e.g., N 2 /5%H 2 ), and the use of specific dopants and dopant mechanisms, which allow the egress of oxygen homogeneously from the lattice. Here, we discuss the processing protocols to fabricate reliable, reproducible ceramic oxides and schemes for inducing high levels of σ, thereby optimizing the power factor (PF = σS 2 ) and ZT. The problems associated with measuring κ, σ, and S to achieve reproducible and accurate values of ZT are discussed, as are future directions which should enable further optimization. Finally, we comment on how these protocols may be applied to other systems and structures.