Effect of Fe-substitution on the structure and magnetism of single crystals Mn2-xFexBO4

Abstract

Single crystalline Mn 2-x Fe x BO 4 with x = 0.3, 0.5, 0.7 grown by the flux method have been studied by means of X-ray diffraction and X-ray absorption spectroscopy at both Mn and Fe K edges. The compounds were found to crystallize in an orthorhombic warwickite structure (sp. gr. P nam ). The lattice parameters change linearly with x thus obeying the Vegard's law. The Fe 3+ substitution for Mn 3+ has been deduced from the X-ray absorption near-edge structure (XANES) spectra. Two energy positions of the absorption edges have been observed in Mn Kedge XANES spectra indicating the presence of manganese in two different oxidation states. Extended X-ray absorption fine structure (EXAFS) analysis has shown the reduction of local structural distortions upon Fe substitution. The magnetization data have revealed a spin-glass transition at T SG = 11, 14 and 18 K for x= 0.3, 0.5 and 0.7, respectively.

Crystal formation of Cu-Mn-containing oxides and oxyborates in bismuth-boron fluxes diluted by MoO3 and Na2CO3

“…After the research stage, the single crystals of Cu-Mn oxyborates with warwickite and ludwigite structures have been grown. In the framework of the assumption of the Na 2 O influence to the crystallization of the trivalent manganese containing compounds and of the MoO 3 influence to the crystallization of the divalent manganese containing compounds the works [26] and [18] have been performed. First of them is devoted to Mn 2-x Fe x BO 4 warwickites, the second oneto Cu 2 Mn 1-x Fe x BO 5 ludwigites.…”

Transformation of structure and magnetic properties of Cu2MnBO5 under partial Mn3+ → Fe3+ substitution

“…x Fe x BO 4 with warwickite structure (it was used the same solvent) [23]. The suggestion based on the solubility of the oxides is proved by the real cation concentration in the synthesized single crystals.…”

“…The large negative paramagnetic temperatures of the samples S2 and S3 (Table 8) indicate the predominance of antiferromagnetic couplings. The Fe-induced cation disorder superimposed on the triangle network of the magnetic moments gives rise to enhance of the magnetic frustration role that is reflected in the large ratio |θ CW |/T c >10 [23] for the samples S2 and S3. The Curie-Weiss temperatures for different directions of the magnetic field are different, and it is a consequence of the anisotropy of the magnetic susceptibility in paramagnetic phase.…”

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

“…Moreover, the correct choice of solvent allows the creation of intermediate chemical bonds (between the components of the solvent and soluble) in the flux system, which contributes to the control of the crystal composition in terms of both the chemical content and the valence state of the cations of one type atom. 18 In addressing these problems, multicomponent fluxes based on Bi 2 O 3 -MoO 3 -B 2 O 3 -Na 2 O proved to be efficient upon the crystallization of heterovalent oxyborates of warwickite 18,[20][21][22] and ludwigite. 18,[23][24][25][26] The change in the valence composition of the manganese cations in the crystallizing phases was shown in the case of using the solvent components MoO 3 (or WO 3 ) and Na 2 O (or Li 2 O).…”