Resistor for the treatment of materials

A resistor for the treatment of materials especially for the production of monocrystalline material and for purifying material by zone melting, said resistor comprising an electrically conductive thin heating plate having a heating surface for exposure to the material to be treated, a second surface opposite the heating surface and a crystallization zone encompassing a selected area of said plate and extending between said surfaces, means defining a plurality of through-holes extending from said heating surface to said second surface in said zone for passage through said plate in said zone of material melted by contact with said heating surface when said plate is heated electrically, said holes being positioned in said zone so that the plate, with respect to an electrical current flowing in said plate parallel to said surfaces, has an electrical resistance which is lower in a peripheral area of said zone than in the central portion thereof.