Crystal growth of ReCa3Mn3O3(BO3)4 (Re = Gd, Y) gaudefroyite: Phase sequence and equilibrium study in multi-component fluxes

Flux growth and phase diversity of the triple oxides of transition metals (Mn,Fe,Ga)2O3in multicomponent fluxes based on Bi2O3–MoO3–B2O3–Na2O

“…For the first time, the oxides Li(Na)-Mn-O with the heterovalent manganese composition were obtained as HTCP for such systems, which proves the direct impact of alkali metal oxide (Li 2 O, Na 2 O) additives on the valence state of manganese cations. 27 The present work continues the study of the influence of the solvent of the multicomponent flux system based on Bi 2 O 3 -MoO 3 -B 2 O 3 -Na 2 O on the phase, chemical and valence composition of the crystallizing substance in an example of triple transition metal oxides (Mn,Fe,Ga) 2 O 3 . In these compounds, manganese is represented only by trivalent cations, as in gaudefroyites.…”

“…Both mechanisms have been experimentally proven. 18,27 With the minimum amount of molybdenum oxide in the flux, HTCP with a bixbyite structure is formed. According to the literature, this phase rather than the orthorhombic one can be formed with a significant manganese content in the crystal.…”

“…The difference appears because of a possible difference in the partition coefficients and the binding of some components with the creation of intermediate chemical bonds. To analyze the relative content of Mn, Ga, Cu, Cr, and Ni atoms in borates of the transition metals with ludwigite 27,30,31 and gaudefroyite 27 structures, the EDX method was used. In the present study, the composition of each sample was studied using EDX.…”

“…18 Recent work considers the crystallization of compounds with a gaudefroyite structure containing only trivalent manganese cations. 27 A direct relationship between the WO 3 /Li 2 O ratio and the valence composition of the manganese cations in HTCP was shown. For the first time, the oxides Li(Na)-Mn-O with the heterovalent manganese composition were obtained as HTCP for such systems, which proves the direct impact of alkali metal oxide (Li 2 O, Na 2 O) additives on the valence state of manganese cations.…”

“…In these compounds, manganese is represented only by trivalent cations, as in gaudefroyites. 27 Another problem of high importance is the study of the partition coefficients of Mn 2 O 3 , Fe 2 O 3 and Ga 2 O 3 oxides upon varying the solvent components in the given flux systems. The characterization of the grown samples was made using XRD, EDX, Mössbauer and Raman spectroscopy methods, allowing one to estimate with a hi accuracy the efficiency of the growth approach in terms of studying the composition control processes (including properties) using the solvent components.…”