Synthesis and Structure of Bulky Single Crystals of High-Entropy Ferrites BaFe12–x(Ti, Mn, In, Ga)xO19.

Large single crystals of high-entropy oxides with the M-type hexaferrite structure, the chemical composition of which can be described by the formula BaFe12–x(Ti, Mn, In, Ga)xO19, are obtained for the first time by spontaneous crystallization from a solution. The actual compositions of the samples are determined: BaFe1.20Ti0.22Mn0.76In0.58Ga0.23O19, BaFe8.71Ti0.44Mn1.16In1.25Ga0.44O19, BaFe7.14Ti0.57Mn1.77In1.79 Ga0.73O19, BaFe5.6Ti0.64Mn2.48In2.52Ga0.76O19. These crystals have a special shape for hexaferrites and are characterized by a fairly uniform distribution of elements in their structure. A significant quantitative difference in the ability of various metal ions to transfer from a melt to a growing crystal is found. A change in the initial ion concentration in the solution has practically no effect on this ability. The influence of crystal compositions on their unit cell parameters is considered. Some increase in these parameters correlates with a decrease in the iron content in the samples. This is mainly due to an increase in the weighted average ionic radius of ions forming the crystals. The configuration mixing entropies within the sublattice formed by Fe, Ti, Mn, In, and Ga for the target compositions and the compositions of actually obtained crystals are calculated and compared. [ABSTRACT FROM AUTHOR]