Room-temperature mechanochemical synthesis of RE molybdates: Impact of structural similarity and basicity of oxides

Igor V. Kolbanev, Anna V. Shlyakhtina, Evgeniy N. Degtyarev, Elena Yu Konysheva, Nikolay V. Lyskov, Dmitriy N. Stolbov, Andrey N. Streletskii

Research output: Journal PublicationArticlepeer-review

3 Citations (Scopus)

Abstract

The feasibility of room-temperature synthesis of R10Mo2O21 (R = La, Y, Er) molybdates via mechanochemical processing of the 5R2O3+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 R2O3 despite the difference in the crystal structure of initial oxides: La2O3 ((Formula presented.), no. 164), Er2O3 and Y2O3 ((Formula presented.), no. 206). Only for the 5Er2O3 + 2MoO3 system containing magnetic cations, ESR detects A-type Mo5+ 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 R10Mo2O21 (R = Y, Er) molybdates have the same bixbyite structure and mechanochemical MoO3 dissolution in these oxides leads to R10Mo2O21 synthesis at room temperature within 80 min. In the La-based system, MoO3 dissolution leads mainly to mechanochemical synthesis of La10Mo2O21 with the same structure as the starting La2O3 ((Formula presented.), no. 164), but the amorphization of La2O3 and formation of basic lanthanum hydroxide during milling also took place. The use of nanosized MoO3 facilitates the slightly formation of La10Mo2O21 ((Formula presented.), no. 164), but makes no impact on the synthesis of La10Mo2O21 ((Formula presented.) (RI), no. 166).

Original languageEnglish
Pages (from-to)5698-5710
Number of pages13
JournalJournal of the American Ceramic Society
Volume104
Issue number11
DOIs
Publication statusPublished - Nov 2021

Keywords

  • bixbyite
  • complex rhombohedral phase
  • electron spin resonance spectroscopy
  • fluorite
  • mechanochemical synthesis
  • phase and structural evolution
  • proton conductor

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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