Micromachined negative thermal expansion thin films

Materials with low coefficients of thermal expansion (CTE) are critically important in thin film design to create efficient bimorph actuators and to thermally stabilize structures of low stiffness. We report the first negative thermal expansion (NTE) material (zirconium tungstate) evaporated as a thin film and probe its CTE using a tunable curvature micromirror. The measured CTE of different films are a function of stoichiometry and annealing conditions and CTEs as low as -10/spl times/10/sup -6/ K/sup -1/ were measured. The measurements show no hysteresis after several annealing cycles. Additionally, data on optical constants, elastic modulus, film stoichiometry, and micromirror deflection have been obtained.