Electric Tunable Structures Based on BaZr_xTi_1–x O₃ and BaSn_xTi_1–xO₃ Solid Solutions for Microwave Applications

Introduction. An experimental study of the structural and electrophysical properties of multicomponent films of solid solutions of barium titanate-zirconate and barium titanate-stannate on sapphire substrates has been carried out. These materials are an alternative to the more studied barium-strontium titanate for use in microwave technology, due to the relatively high controllability. In this paper, it is shown that when using post-post high-temperature annealing, films with a component composition close to the composition of the sprayed targets are formed on the substrate. Optimal deposition temperatures of thin films of barium titanate-zirconate and barium titanate-stannate have been determined to obtain the best electrophysical parameters.
Aim. Investigation of structural and microwave properties of BaZr_xTi_1-xO₃ (BZT) and BaSn_xTi_1–xO₃ (BSnT) films on dielectric substrates. These ferroelectric materials are promising in terms of losses and nonlinearity, and the formation of planar structures based on these materials on a dielectric substrate allows for a significantly higher level of operating power of the microwave device.
Materials and methods. The crystal structure and phase composition of the obtained films were studied by X-ray diffraction using a DRON-6 diffractometer on the emission spectral line CuKa1 (λ = 1.5406 Å). Capacitance C and Q-factor (Q = 1/tg δ) of capacitors were measured at frequencies of 1 and 3 GHz using a resonator and an HP 8719C vector analyzer.
Results. It is established that high-temperature annealing after film deposition has a significant effect on the crystal structure, phase composition of films and their electrical characteristics. For the first time, a low level of dielectric losses of planar capacitive elements based on titanate-stannate and barium titanate-zirconate films in the frequency range of 1…60 GHz with acceptable controllability has been demonstrated.
Conclusion. The results obtained indicate the prospects of using thin ferroelectric films of BaSn_0.5Ti_0.5O₃ and BaZr_0.5Ti_0.5O₃ solid solutions in microwave devices.

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