Room‐temperature mechanochemical synthesis of RE molybdates: Impact of structural similarity and basicity of oxides. Issue 11 (16th June 2021)

• Record Type: Journal Article
• Authors: Kolbanev, Igor V.; Shlyakhtina, Anna V.; Degtyarev, Evgeniy N.; Konysheva, Elena Yu.; Lyskov, Nikolay V.; Stolbov, Dmitriy N.; Streletskii, Andrey N.
• Is Part Of: Journal of the American Ceramic Society. Volume 104:Issue 11(2021)
• Page Start: 5698
• Page End: 5710
• Publication Date: 2021-06-16
• Subjects: bixbyite -- complex rhombohedral phase -- electron spin resonance spectroscopy -- fluorite -- mechanochemical synthesis -- phase and structural evolution -- proton conductor; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.17939
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: The feasibility of room‐temperature synthesis of R10 Mo2 O21 (R = La, Y, Er) molybdates via mechanochemical processing of the 5R2 O3 +2MoO3 oxide mixtures has been studied using X‐ray powder diffraction (XRD) with Rietveld refinement and electron spin resonance spectroscopy (ESR). In all systems, the initial stage of mechanochemical synthesis is associated with MoO3 dissolution in R2 O3 despite the difference in the crystal structure of initial oxides: La2 O3 ( P 3 ¯ m 1, no. 164), Er2 O3 and Y2 O3 ( I a 3 ¯, no. 206). Only for the 5Er2 O3 + 2MoO3 system containing magnetic cations, ESR detects A‐type Mo 5+ centers, thus enabling to follow the decrease in MoO3 content during room‐temperature mechanochemical synthesis. In the Er‐ and Y‐based systems, the starting oxides and synthesized R10 Mo2 O21 (R = Y, Er) molybdates have the same bixbyite structure and mechanochemical MoO3 dissolution in these oxides leads to R10 Mo2 O21 synthesis at room temperature within 80 min. In the La‐based system, MoO3 dissolution leads mainly to mechanochemical synthesis of La10 Mo2 O21 with the same structure as the starting La2 O3 ( P 3 ¯ m 1, no. 164), but the amorphization of La2 O3 and formation of basic lanthanum hydroxide during milling also took place. The use of nanosized MoO3 facilitates the slightly formation of La10 Mo2 O21 ( P 3 ¯ m 1, no. 164), but makes no impact on the synthesis of La10 Mo2 O21 ( R 3 ¯ m (RI), no. 166). Abstract : Room‐temperature R10 Mo2 O21 (R = Er, Y, La) mechanochemical synthesis.