Abstract: Composite materials comprised of NiCu alloy and Nd tungstates are promising materials for hydrogen separation membranes due to their high mixed protonic-electronic conductivity [1]. This work aims at studying structural and transport features of Nd5.5WO11.25-δ-based oxides and their composites with Ni0.5Cu0.5O. Nd5.5WO11.25-δ, Nd5.5W0.5Mo0.5O11.25-δ and (Nd5/6La1/6)5.5WO11.25-δ and their composites with Ni0.5Cu0.5O (35 wt.%) were synthesized by the mechanical activation and sintered at 1100 °C. The materials were characterized by XRD and TEM. Their oxygen mobility and surface reactivity were studied by temperature programmed isotope exchange with C18O2 in a flow reactor. Nd5.5WO11.25-δ, Nd5.5W0.5Mo0.5O11.25-δ and (Nd5/6La1/6)5.5WO11.25-δ were single-phase distorted double fluorites or contain small amounts of Nd2O3 admixture, while their composites contained fluorite phase and Ni(II)-Cu(II) oxide phase. Extended defects such as grain boundaries, stacking faults and surface steps/terraces were detected for oxide materials. Very fast oxygen diffusion (D*~10-5 cm2/s at 700 °C) along grain boundaries and slower diffusion (D*~10-10 cm2/s at 700 °C) within grains’ bulk were demonstrated for oxide materials [2]. For composite materials, drastic decrease in oxygen diffusivity was shown probably due to blocking fast diffusion along grain boundaries by Ni0.5Cu0.5O nanoparticles. Reduction and subsequent reoxidation of composites resulted in slight increase in oxygen mobility probably due to partial unblocking of fast diffusion along grain boundaries

Cite: Sadykov V.A. , Bespalko Y.N. , Eremeev N.F. , Skriabin P.I. , Krasnov A. , Sadovskaya E.M. , Krieger T.A. , Ishchenko A.V.
Structural and Transport Properties of Neodymium Tungstates and Their Composites with Nickel (II) – Copper (II) Oxide
12th International Conference on Hydrogen Production 19-23 Sep 2021