Crystal pulling from a highly impure growth melt

A molten oxide electrolysis (MOE) system comprising:

• a first vessel that includes i) an anode and ii) a cathodic electrode in a bottom region of the first vessel, wherein
• the cathodic electrode is configured to be in electrical communication with a melted oxide material in the first vessel,
• the anode and the cathodic electrode are configured to provide an electrical current therebetween for a process of electrolysis of the melted oxide material, and
• the process of electrolysis of the melted oxide material produces a liquid cathode in contact with the cathodic electrode;
• a second vessel that is separated from the first vessel by a conduit for carrying, from the first vessel to the second vessel, a portion of the melted oxide material that is iron- and oxygen-depleted, wherein the portion of the melted oxide material that is iron- and oxygen-depleted is a growth melt;
• a rod-mounted seed crystal of an element in or above the second vessel and configured to be immersed in the growth melt;
• and
• temperature-control electronics configured to control the temperature of the growth melt based, at least in part, on a melt profile that represents a melt temperature of the growth melt as a function of the concentration of the element.