(Ba0.6,Sr0.4)TiO3 (BST) films were deposited on copper foils by radio frequency magnetron sputtering. By the use of controlled pO2 high-temperature anneals, the films were completely crystallized in the absence of substrate oxidation. X-ray diffraction and transmission electron microscopy (TEM) revealed an abrupt Cu/BST interface. The deposited BST films exhibit a zero bias permittivity and loss tangent values of 600 and 0.018, respectively. An electrical tunability ratio of 3.5:1 is observed on these metal–insulator–metal devices. Devices show leakage currents of 10−8 A/cm2 at ±10 V/m, and loss tangents as low as 0.003 in fields approaching 40 V/m.