Abstract: The present invention relates to rhomboidal phase bismuth oxide that maintains electric conductivity of at least about 1×10?2 S/cm at temperature of about 500° C. for at least about 100 hours. In particular, the bismuth oxides of the invention have stable conductivity at a temperature range from about 500° C. to about 550° C.

Abstract: A two-part, high-density card retention system includes a tapered channel in a chassis or housing and a mating wedge that runs the length of the housing, with the lead wedge being cammed towards a flat channel surface by drawing the wedge inwardly and locating the edge of the board to be mounted between the wedge and the opposing straight channel wall. The mounting provides continuous high-pressure contact between the board and the straight channel wall for maximal thermal transfer and robust anti-vibration and anti-shock mounting of the board to the chassis. Because no additional assemblies are mounted to the edge of the board, the boards may be spaced apart by a fine pitch, thus to minimize the size of the module into which the boards are mounted.