Abstract
A method is described of preparing Cr foils as thick as 20 to 50mg/cmcm2, to be used as targets in the production of 52Fe.
The Cr was electroplated from an electrolyte solution (300g/l CrO3, 2.0g/l H2SO4 of s.g., 7.0g/l Na2SiF6) on a pure Cu sheet and then the Cu was removed by dissolution in (1:1) HNO3. Free Cr foil thus obtained was soaked in a 1:1 mixture of 20% NH4OH and 10% (NH4)2S2O8 for 30min. After the foil was washed with water, it was heated at 120° to 150°C.
For the electroplating, a cell with Pt anode and Cu sheet cathode was made of Lucite (cell (a)) and of glass (cell (b)), with deposition areas of 2.54cmcm2 and 7.07cmcm2, respectively. Direct current (6V) was supplied from a storage battery.
For the preparation of enriched 50Cr targets, the electrolysis conditions were studied in detail. Using cell (a), the electrolysis could be performed without rotating the anode, at 275mA/cmcm2 with an average current efficiency of-20%, after striking at 2A (787mA/cmcm2) for 40 to 60 sec. After 4 hr a foil of 60mg/cmcm2 thickness was obtained from 3-5ml of the electrolyte solution with a deposition yield of 32%.
For the preparation of natural Cr target with use of cell (b), the striking was at 3.0 to 2.5A for 40-60 sec, and the electroplating was continued for 90 to 120 min at 250-300mA/cmcm2 while rotating the anode, resulting in foils of 20-40mg/cmcm2 thickness and 30mm in diameter.
