A complex perovskite oxide, YbBa₂NbO₆, as a non-reacting substrate for YBa₂Cu₃O_7–𝛿 superconducting film has been developed. The dielectric constant and loss factor values of the material are in the range suitable for its use as substrate for microwave application. A YBa₂Cu₃O_7–𝛿 superconducting thick film dip coated on YbBa₂NbO₆ substrate gave a 𝑇_c (0) of 92 K and current density of ∼ 1.3 × 10⁴ A cm^-2.

Barium erbium niobate (Ba₂ErNbO₆) has been developed as a new substrate for (Bi,Pb)₂Sr₂Ca₂Cu₃O_𝑥 [Bi(2223)] superconductor film. Ba₂ErNbO₆ (BENO) has a cubic perovskite structure with lattice constant, 𝑎 = 8.318 Å. The Bi(2223) superconductor does not show any detectable chemical reaction with BENO even under extreme processing conditions. Dip coated Bi (2223) thick film, Ba₂ErNbO₆ substrate, gave a 𝑇_c (0) of 110 K and current density of ∼ 4 × 10³ A cm^-2 at 77 K and zero magnetic field.

Nanoparticles of barium gadolinium antimonate (Ba₂GdSbO₆), a complex perovskite-type oxide, has been synthesized using an auto ignition combustion process for the first time. The nanoparticles thus obtained have been characterized by powder X-ray diffraction, thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy and transmission electron microscopy. The XRD studies have shown that the as-prepared powder is phase pure Ba₂GdSbO₆ and has a complex cubic perovskite (A₂BB′O₆) crystalline structure with lattice constant, 𝑎 = 8.449 Å. The TEM image reveals that the particle size of the as-prepared nano powder was in the range 30–60 nm. The nanocrystals of Ba₂GdSbO₆ synthesized by the combustion technique could be sintered to 96% of the theoretical density by heating at a temperature of 1560°C for a short duration of 3 h. The surface morphology of the sintered pellet has been studied by scanning electron microscope (SEM). The dielectric constant ($\varepsilon_{r}$) was 20 and the loss factor (tan𝛿) was 0.03 at 3 MHz. By the present combustion technique a phase pure nanopowder of Ba₂GdSbO₆ could be obtained by a single step process without the need of any calcination step.