High oxygen conductivities can be achieved in cation ordered LnxZrl_=O2_l x (Ln=Gd, Nd) solid solutions with pyrochlore (P) structure. High values of the pre-exponentlal factor °o are correlated with the degree of anion disorder in the 8b oxygen sublattice (neutron diffraction). The activation energy AH is lowered by cation ordering (F-P transition; effect of x) due to the occurence of a prefer...

Alkali halides and alkaline earth halides are strongly ionic compounds that solidify as crystals. The name for the alkali elements (Li, Na, K, Rb and Cs) comes from the Arabic word alqili (ashes of the salt-wort plant that was once used as a source of sodium and potassium for making glass from sand). The name for the halogen elements (F, Cl, Br, I—and the rare radioactive element astatine) come...

Solid Oxide Fuel Cells (SOFC) offer electrochemically generated sources of electricity using oxygen ion transport at elevated temperatures. Analysis of materials used in SOFC using electron microscopy provides insights of foreseeable chemical reactions that govern the performance of the fuel cell. Materials used in SOFC can be divided into four categories; anode, cathode, electrolyte and interc...

The response of allanite-(Ce) in the Eocene Casto granite of Idaho to hydrothermal activity has been investigated. Unaltered, igneous allanite from the Casto pluton is characterized by a narrow range of compositional variation, with little or no zoning. A representative empirical formula, based on the composition of the least-altered grain, is: (REE0.83Ca1.07Th0.04Mn0.06) (Ti0.11 Mg0.04Fe0.99Fe...

Fluorite is a nonrenewable mineral used to produce anhydrous hydrofluoric acid (AHF) and aluminum fluoride. The demand for low-grade fluorite powder (CaF2 < 97%) has fallen sharply owing the current market conditions. Therefore, large number of concentrates have been improved by leaching. While this approach can efficiently remove CaCO3 from concentrate, SiO2 content, which significantly aff...

Hydrogen permeation membranes are a key element in improving the energy conversion efficiency and decreasing the greenhouse gas emissions from energy generation. The scientific community faces the challenge of identifying and optimizing stable and effective ceramic materials for H2 separation membranes at elevated temperature (400-800 °C) for industrial separations and intensified catalytic rea...