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Transition-metal oxide (TMO) glasses have long been studied for their electrical conductivity. 1,2 Both fundamental understanding of the conduction mechanism and electrical property measurements have been the subjects of numerous investigations. 3 The highest conductivities have been measured on phosphate glasses containing transition-metal ions such as vanadium, molybdenum, tungsten, and iron with mixed oxidation states. The glasses are typically semiconducting and exhibit DC conductivities ranging from 10 −9 to 1 S/m.Glass-ceramics in the WO 3 -TiO 2 -P 2 O 5 (WTP) system with unusually high electrical conductivity, up to ~6000 S/m, were first reported by Aitken. 4 In a recent article, one of the primary phases in these glass-ceramics was identified as a tungsten monophosphate from the series (PO 4 ) 2 (WO 3 ) 2m . 5 As the ceramming temperature increased, the phase assemblage changed from a mixture of WO 3 , TiP 2 O 7 , and tungsten phosphate to tungsten phosphate and titanium phosphate only. The microstructure was described as an interconnecting network of prismatic tungsten phosphate crystals in a TiP 2 O 7 matrix.The thermoelectric behavior of a material is defined by its electrical conductivity (σ), Seebeck coefficient (α), and thermal conductivity (κ). From these data, the dimensionless figure-of-merit (ZT) is calculated as: 6The conversion efficiency of a thermoelectric power generator is related to the ZTs of the p-type and n-type elements, with ZT >1 generally considered a requirement. [6][7][8] Efficiency is also directly related to the temperature gradient across the elements, and, therefore, materials that can operate at high temperatures are desired.Electrically conductive, oxide ceramics have been widely investigated for their potential use as high-temperature thermoelectrics. 7,9 At least two challenges face these materials. The first is identifying oxides that meet the ZT >1

The performance of electrochemical devices like fuel cells is strongly affected by the transport of electrons between interconnects and active regions of an electrode. We examine the use of an auxiliary, precious metal current distributor placed over the cathode of a solid oxide fuel cell to supplement the transport process. Cell resistance was minimized by computer modeling as a function of the shape of the structure under the constraint that its total volume is fixed. The optimal shapes are shown to be fractals that resemble structures found in nature. A thin fractal current distribution structure made from platinum was demonstrated to facilitate the transport process in oxygen pump cells constructed from porous lanthanum strontium manganite (LSM) - yttria-stabilized zirconia (YSZ) composite electrodes on a 15 µm thick tape of 3 mol percent YSZ.