Single-phase, non-cubic and single-phase, cubic ferroelectric/paraelectric perovskite-structured materials having reasonably low and fairly temperature insensitive dielectric constants (stable dielectric constants over a wide range of operating temperatures of −80° C. to 100° C.), reasonable loss tangents (<˜10−1), high tunability, and significantly lowered Curie temperature below the temperature range of operation for previous undoped perovskite structures are provided. The FE/PE materials of the present invention have dilute charge-compensated substitutions in the Ti site of the perovskite structure. This single-phase structure or a variant of it with a Ti rich composition, provided herein, allows for pulsed-laser-deposition of a thin film with uniform transfer of the structure of the target into the deposited film, which enables production of very small, lightweight devices that are extremely efficient and consume little power. These ferroelectric/paraelectric materials may be used in phase shifter devices (such as used in cell phones, antennas and the like), variable true time delay devices, steerable beams, tunable filters, impedance transformers, variable control oscillators, antennas, radios, filters, microwave variable capacitors, radar systems, electronic warfare sensors, resonators, microwave transverse-electromagnetic-ferroelectric voltage-controlled oscillators, and other RF, microwave, or millimeter wave tunable devices for synthesizers and systems incorporating all of the above, as well as any application that enhances the performance of various types of electrical and electro-optic devices.