公开(公告)号：US3282641A

公开(公告)日：1966-11-01

申请号：US31495363

申请日：1963-10-09

Applicant: HARSHAW CHEM CORP

Inventor： MARKO SFILIGOJ ,  SWINEHART CARL F

IPC: C01D3/20 ,  C01F5/28 ,  C01F11/22 ,  C01F17/00 ,  C01G1/06 ,  C30B11/00 ,  G02B1/02

CPC classification number: G02B1/02 ,  C01D3/20 ,  C01F5/28 ,  C01F11/22 ,  C01F17/0062 ,  C01G1/06 ,  C30B11/00 ,  C30B29/12

Abstract: A colour-free crystal of alkaline earth or rare earth fluorides is obtained by melting and solidifying the fluorides in the presence of the vapour of CoF3 and/or MnF3. Fluorides of Mg, Ca, Sr, Ba, and all the rare earths La-Lu are specified, and mixtures, e.g. BaF2 with 10-30% CaF2. They may be synthetic (obtained by reacting acetate, carbonate, or nitrate with HF) or natural, e.g. fluorspar, and may be solid bodies grown previously from a melt but having an optical defect, or may be comminuted. The CoF3 or MnF3 in amounts of 0.25-2% b.w. of the charge is placed in a vented cup above the fluoride charge in a crucible, and vaporizes as the charge melts. The crucible is then lowered into a cooler zone across a sharp temperature gradient to effect crystal growth. The melt may also include 1-4% b.w. lead fluoride with or without PbO or Pb3O4 and Pb metal, or 0.05-0.2% V metal; alternatively the additive metal may be placed in a vented cup.ALSO:A colour-free crystal of alkaline earth or rare earth fluorides is obtained by melting and solidifying the fluorides in the presence of the vapour of CoF3 and/or MnF3. Fluorides of Mg, Ca, Sr, Ba, and all the rare earth La-Lu are specified, and mixtures, e.g. BaF2 with 10-30% CaF2. They may be synthetic (obtained by reacting acetate, carbonate, or nitrate with HF) or natural, e.g. fluorspar, and may be solid bodies grown previously from a melt but having an optical defect, or may be comminuted. The CoF3 or MnF2 in amounts of 0.25-2% b.w. of the charge is placed in a vented cup above the fluoride charge in a crucible, and vaporises as the charge melts. The crucible is then lowered into a cooler zone across a sharp temperature gradient to effect crystal growth. The melt may also include 1-4% b.w. lead fluoride with or without PbO or Pb3O4 and Pb metal, or 0.05-0.2% V metal; alternatively the additive metal may be placed in a vented cup.