Electronic transport in LTCC highly conductive RuO/sub 2/+ glass sinters

The resistors, made of inks with the high content of conductive oxide in a standard "on-alumina" process are subjected to easy rubbing off. The use of LTCC technology enables embedding the samples inside a ceramic substrate which make them insensitive to any mechanical exposure. Following this idea a resistive paste containing as much as 95 vol. % of RuO/sub 2/ powder and only 5 % of glass frit has been prepared. The sheet resistance we got was /spl sim/ 1.5 /spl Omega//square at room temperature. The resistance versus temperature dependence R(T) reveals metallic-like behavior. The intrinsic resistivity extracted from resistivity data is an order of magnitude larger than that of crystalline RuO/sub 2/. This resistivity increase is due to the formation of small contacts between RuO/sub 2/ grains - R(T) is well fitted with the equation in which both Maxwell and Sharvin components of contact resistance are taken into account. It is shown that scattering mechanisms proposed by Glassford and Chelikowsky [Phys. Rev. B 49 (1994) 7107] and by Ryden Lawson and Sartain [Phys. Rev. B 1 (1970) 1494] for RuO/sub 2/ crystal are applicable to the sinters of nanosized RuO/sub 2/ grains.