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Room‐temperature mechanochemical synthesis of RE molybdates: Impact of structural similarity and basicity of oxides
Author(s) -
Kolbanev Igor V.,
Shlyakhtina Anna V.,
Degtyarev Evgeniy N.,
Konysheva Elena Yu.,
Lyskov Nikolay V.,
Stolbov Dmitriy N.,
Streletskii Andrey N.
Publication year - 2021
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17939
Subject(s) - dissolution , electron paramagnetic resonance , crystal structure , crystallography , lanthanum , bixbyite , oxide , rietveld refinement , chemistry , materials science , inorganic chemistry , metallurgy , nuclear magnetic resonance , physics
The feasibility of room‐temperature synthesis of R 10 Mo 2 O 21 (R = La, Y, Er) molybdates via mechanochemical processing of the 5R 2 O 3 +2MoO 3 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 MoO 3 dissolution in R 2 O 3 despite the difference in the crystal structure of initial oxides: La 2 O 3 ( P 3 ¯ m 1 , no. 164), Er 2 O 3 and Y 2 O 3 ( I a 3 ¯ , no. 206). Only for the 5Er 2 O 3 + 2MoO 3 system containing magnetic cations, ESR detects A‐type Mo 5+ centers, thus enabling to follow the decrease in MoO 3 content during room‐temperature mechanochemical synthesis. In the Er‐ and Y‐based systems, the starting oxides and synthesized R 10 Mo 2 O 21 (R = Y, Er) molybdates have the same bixbyite structure and mechanochemical MoO 3 dissolution in these oxides leads to R 10 Mo 2 O 21 synthesis at room temperature within 80 min. In the La‐based system, MoO 3 dissolution leads mainly to mechanochemical synthesis of La 10 Mo 2 O 21 with the same structure as the starting La 2 O 3 ( P 3 ¯ m 1 , no. 164), but the amorphization of La 2 O 3 and formation of basic lanthanum hydroxide during milling also took place. The use of nanosized MoO 3 facilitates the slightly formation of La 10 Mo 2 O 21 ( P 3 ¯ m 1 , no. 164), but makes no impact on the synthesis of La 10 Mo 2 O 21 ( R 3 ¯ m (RI), no. 166).