[en] Ranges of crystallization of Y₃Fe₅O₁₂ and phases borderind on it in the P-Y₂O₃-Fe₂O₃ pseudoternary system (P being the sum of PbO, PbF₂ and B₂O₃ moles) are plotted during varying the solvent composition in the following ranges: PbF₂ from 0.5 to 2; B₂O₃ - from 0.2 to 0.65 mol. relatively to 1 mol. PbO. On the basis of this diagrams chemical interactions between solution components are analyzed; and alongside with formerly known YFeO₃, Fe₂O₃, PbFe₁₂O₁₉, the Y₄O₃F₆ phase is separated. It is shown that the highest solubility of Y₃Fe₅O₁₂ takes place in the compositions enriched by PbF₂. The values of Y₃Fe₅O₁₂ mass growth rate on seeds in solutions - melts with the concentration of 3-5 and 12-16 weight%, which are 0.01-0.04 and 0.2-0.3 g/hr, respectively, are presented