Nd—doped BaCeO3 is reported to be an excellent high—temperatureprotonic conductor, while the Gd—doped material is not. In order to better understand the role of different dopants, we have studied BaCeO3 doped with 5 mol% of each Nd3+, Eu3+, Gd3+, Yb3+ and Ca2+. In each case samples were treated in an appropriate gas atmosphere at 900ºC followed by measurement from 25 to 200ºC in a “frozen—in”state. Protonic conduction was deduced from the isotope effect, i.e. comparing conductivity after treatment in D2O—saturated gas with that for H20,as well as by the change between wet and dry treatments. In addition, we measured H2O uptake by observing the weight change between wet and dry treatments, and also carried out some galvanic cell measurements. It was concluded that, of the above dopants, only Nd and Ca give rise to appreciable protonic conduction. In the Nd case, the low activation energy of 0.54 eV is probably the proton hopping energy. On the other hand, Eu, Gd and Yb—doped materials appear to show the dominance of oxygenion conduction in the low temperature range and mixed oxygen—ion and electron—hole conductivity at elevated temperatures. The most likely reason for these differences seems to be centered on the ionic radii of the dopants.

The results of audio frequency complex impedance studies for vanadyl phosphate and its hydrates (VOPO4*nH2O;n=0,1,2) are reported. Measurements were made at seventeen frequencies between 10 and 105 Hz over the temperature range 5.5-380K. Two lowtemperature features were observed and are correlated with particular water species between the VOPO4 layers. In light of chemical evidence and compleximpedance measurements on related compounds, it is speculated that VOPCO4*nH2O (Pc = P, As) can be thought of as a mixed nonstoichiometric compound [VO(HPcO4)]x[VOPcO4O4]1-x*nH2O and the solid Brϕnsted acid nature of the compound is related to proton movement between layer pnictates and intralayer waters.

The lithium derivatives from anhydrous niobium (Y) phosphate were made through NbOPO4.H20 and LiCl by solid state reaction at 200 ºC and subsequentannealed at 500ºC. The solid with the highest lithium content, exhibits the maximum conductivity of all materials prepared. The electrical conductivity of this solid ranges from 10-10 Ω-1 cm-1 at 373K to 3.62.10-3Ω-1cm-1 at 683K.

The search for lithium ion conductors in crystalline or polycrystalline solid state ionic materials has resulted in finding a new class of compounds. Five new, stable, homogeneous compounds formed in the lithium alcohol systems, LiI—(ROH)x for R=CH3CH2OH, CH3CH2CH2OH, CH3CHOHCH3,, and CH3OH have been identified and characterized.

The transport properties of the pyrochlore solid solution Gd2(ZrxTil-x)2O7 are investigated to clarify the relationships between composition, structural disorder and ionic and electronic transport. The oxygen ion conductivity has been found to increase sharply with increasing Zr content, x, due to enhanced structural disorder, leading to intrinsic ionic conduction at large values ofx. In contrast, the n—type conductivity predominant at low x, decreases sharply above x=0.2. Defect chemical models are presented to account for the simultaneous contributions of both intrinsic and dopant induced disorder. These models are applied to the σ(T, PO2, dopant) data to extract key thermodynamic and transport parameters. The significance of these parameters and the potential application of these materials in electrochemical devices are discussed.