Electrical resistivity and lattice parameters of sputtered iridium alloys

Abstract Films of iridium and Ir-Cr, Ir-Mo, Ir-W, Ir-Re and Ir-Pt alloys were prepared by r.f. sputtering on Al 2 O 3 substrates. Because an asymmetric target arrangement was used for the iridium and alloying elements the sputtered films had a defined compositional gradient. Resistance probes, 1 × 5 mm in area, with well-defined alloy composition were cut out of the film using a computer-controlled laser. The electrical resistivity of the alloys was measured between 4 and 684 K. The temperature coefficient of the resistivity at 283 K varies with the composition from 400 to 1500 ppm K -1 . The increase in resistivity with impurities is 2.04, 3.65, 3.02, 2.70 and 1.33 μΩ cm at.% -1 for chromium, molybdenum, tungsten, rhenium and platinum respectively. The linear size factor (1/ a 0 ) (d a /d c ) c = 0 is -7.0%, +3.0%, +3.0%, +0.1% and +2.0% for chromium, molybdenum, tungsten, rhenium and platinum respectively.