End closure members for discharge lamps

Claim 1

An electrically conducting cermet comprising a sintered compact of refractory oxide granules having diameters of from 50 to 800 microns, and a conductive network extending throughout the cermet wherein said network is provided by a layer of metal, said layer comprising niobium and, optionally, at least one other metal selected from titanium, zirconium, hafnium, vanadium, tantalum, molybdenum and tungsten, said layer constituting a volume fraction of 0.06 to 0.2 of the cermet and the minimum niobium content of said layer constituting a volume fraction of 0.06 of the total cermet, and wherein said granules comprise 0.01 to 0.25 percent by weight of the refractory oxide of finely divided magnesium oxide and either: (a) a refractory oxide selected from the group consisting of aluminium oxide, yttrium oxide or a spinel, or (b) a refractory oxide such as aluminium oxide, yttrium oxide or a spinel and at least one metal selected from titanium, zirconium, hafnium, vanadium, tantalum, chromium, molybdenum, tungsten, iron, cobalt and nickel in a volume fraction of from 0.01 to 0.15 of the total volume of the granules.