Aqueous Sol–Gel Route toward Selected Quaternary Metal Oxides with Single and Double Perovskite-Type Structure Containing Tellurium

Highly crystalline SrFe2/3Te1/3O3, Ba3Fe2TeO9, and Ba2NiTeO6 have been synthesized by using a specially developed sol–gel route methodology, reducing the time needed employing solid-state routes and resulting in high reaction yield up to 75%. These materials have been studied by X-ray powder diffraction (XRPD), scanning and transmission electron microscopy, Raman spectroscopy, and dielectric and magnetic measurements. At room temperature, the crystal structure of SrFe2/3Te1/3O3 is cubic, space group Pm3m, with a = 3.9373(2) A, whereas Ba3Fe2TeO9 crystallizes in the hexagonal crystal system, space group P63/mmc, a = 5.7691(4) A, and c = 14.208(1) A. The third studied perovskite Ba2NiTeO6 crystallizes in the trigonal R3m space group with a = 5.7974(4) A and c = 28.599(2) A. Based on structural characterization results, the obtained single and double perovskite crystallites are nearly in nanometer regime, ranging from 45 to 164 nm, building micrometer-sized particles with visible well-faceted hexagonal mor...