Elastic constants of single-crystal TiNx(001) (0.67≤x≤1.0) determined as a function of x by picosecond ultrasonic measurements -: art. no. 144106

The elastic constants c(11) and c(44) of single-crystal NaCl-structure delta-TiNx(001) layers, with x ranging from 0.67 to 1.0, were determined using sound velocity measurements. Picosecond ultrasonic optical pump/probe techniques were employed to generate and detect longitudinal sound waves and surface acoustic waves (SAW) in order to obtain c(11)(x) and c(44)(x), respectively. SAW generation was achieved by depositing a periodic series of Al bars on the TiNx(001) layers to spatially modulate the surface reflectivity. c(11) and c(44) were found to decrease continuously from 626 and 156 GPa with x=1 to 439 and 92 GPa with x=0.67. The Voit-Reuss-Hill average aggregate elastic moduli E-VRH(x) obtained from our measured c(11)(x) and c(44)(x) values are in good agreement with previous TiNx(001) nanoindentation results.