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

Abstract

Highly crystalline SrFe 2/3 Te 1/3 O 3 , Ba 3 Fe 2 TeO 9 , and Ba 2 NiTeO 6 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 SrFe 2/3 Te 1/3 O 3 is cubic, space group Pm3̅ m, with a = 3.9373(2) Å, whereas Ba 3 Fe 2 TeO 9 crystallizes in the hexagonal crystal system, space group P6 3 /mmc, a = 5.7691(4) Å, and c = 14.208(1) Å. The third studied perovskite Ba 2 NiTeO 6 crystallizes in the trigonal R3̅ m space group with a = 5.7974(4) Å and c = 28.599(2) Å. 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 morphology. Magnetic measurements show the onset of ferrimagnetic ordering at relatively high temperature of 667 K for the SrFe 2/3 Te 1/3 O 3 , whereas Ba 3 Fe 2 TeO 9 and Ba 2 NiTeO 6 show antiferromagnetic ordering below 80 and 8.6 K, respectively. The measured room temperature dielectric constants are in the range between 15 and 77.

Synthesis and Study of the Effect of Ba2+ Cations Substitution with Sr2+ Cations on Structural and Optical Properties of Ba2−xSrxZnWO6 Double Perovskite Oxides (x = 0.00, 0.25, 0.50, 0.75, 1.00)

“…Many researchers are interested in double perovskite oxides that consist of transition metals [ 1 ]. These materials represent a large part of material science research because of the diversity in their physical and chemical characteristics, and their diverse applications [ 1 , 2 , 3 , 4 , 5 , 6 ], such as light harvesting (LaNiMnO 6 ) [ 2 ], ferroelectrics (Pb 2 Mn 0.6 Co 0.4 WO 6 ) [ 5 ], Multiferroic (Bi 2 NiMnO 6 , Bi 2 FeCrO 6 ) [ 6 ], superconductivity (Sr 2 YRu 0.95 Cu 0.05 O 6 ) [ 7 ], magneto resistance (Sr 2 FeMoO 6 ) [ 8 ], dielectric resonators (Ca 2 AlTaO 6 , SrAlTaO 6 ) [ 9 ], and photo-catalysis (Cs 2 BiAgCl 6 ) [ 10 ].…”

Rational Sol–Gel-Based Synthesis Design and Magnetic, Dielectric, and Optical Properties Study of Nanocrystalline Sr3Co2WO9 Triple Perovskite

“…The sharp peaks appearing in the range from 100−150 cm −1 are assigned to lattice translational modes (111 and 128 cm −1 ). 29 There are also some very low-intensity broad peaks appearing in the ranges from 400−500 cm −1 that can be assigned to the asymmetric stretch (ν 2 = 470 cm −1 ) and an oxygen bending motion of the octahedron (ν 5 = 440 cm −1 ).…”

“…Octahedrally coordinated Co 3+ (0.61 Å) and Fe 3+ (0.645 Å), W 6+ (0.60 Å), and Te 6+ (0.56 Å) have also similar ionic radii . This might indicate that Sr 3 Co 2 WO 9 could be structurally similar to Sr 3 Fe 2 WO 9 which was already repeatedly synthesized in bulk form using solid-state route − and recently also in the form of a nanomaterial, as well as Sr 3 Fe 2 TeO 9 …”

“…Since iron triad group compounds generally share similar physicochemical properties, these materials caught our attention. The focus of our previous work was an iron-containing triple perovskite, , which is why we decided to expand it to other iron triad group compounds. Bottom up approaches allow shape- and size-control over the design of the targeted compounds .…”

“…24 This might indicate that Sr 3 Co 2 WO 9 could be structurally similar to Sr 3 Fe 2 WO 9 which was already repeatedly synthesized in bulk form using solid-state route 25−27 and recently also in the form of a nanomaterial, 28 as well as Sr 3 Fe 2 TeO 9 . 29 Triple perovskites with Sr 3 B 2 WO 9 structure type, where B is an iron triad cation, 30 instead of iron, are poorly investigated. Since iron triad group compounds generally share similar physicochemical properties, these materials caught our attention.…”