Earlier we reported the room-temperature phase equilibria in MF2-YF3 (M = Ba, Sr, and Ca) systems. In the present study, synthesis and characterization of the Y1-xMg2+1.5xF7 (-1.33 less than or equal to x less than or equal to 1.0) compounds were attempted, to establish a similar phase relation in the MgF2-YF3 system. Neither YF3 in MgF2 nor MgF2 in YF3 was found to have solubility under slow-cooled conditions.