title: Electrolytic coloration and spectral properties of natural fluorite crystals containing oxygen impurities.
abstract: Natural fluorite crystals containing oxygen impurities are colored electrolytically by using a pointed cathode and a flat anode at various temperatures and voltages. F and F(2) color centers are produced in colored fluorite crystals. O(2-)-V(a)(+), O(2-)-V(a)(+) aggregate, Yb(2+), Ce(3+) and Sm(2+) absorption bands are observed in absorption spectra of uncolored fluorite crystals. O(2-)-V(a)(+), O(2-)-V(a)(+) aggregate, Yb(2+), Ce(3+), Sm(2+), F, M (F(2)) absorption bands and group of four absorption bands are observed simultaneously in absorption spectra of colored fluorite crystals. Current-time curve for electrolytic coloration of natural fluorite crystal and its relationship with electrolytic coloration process are given. Production and conversion of color centers are explained.
authors.affiliation: Department of Physics, Tianjin University, Tianjin 300072, PR China. jthgu@163.com
authors.forename: Hongen
authors.initials: H
authors.lastname: Gu
authors.forename: Dongliang
authors.initials: D
authors.lastname: Ma
authors.forename: Weiwei
authors.initials: W
authors.lastname: Chen
authors.forename: Rui
authors.initials: R
authors.lastname: Zhu
authors.forename: Yutong
authors.initials: Y
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
mesh_terms: D002586:Cesium / Q000737:chemistry; D002621:Chemistry / Q000379:methods; D003116:Color; D003460:Crystallization; D004058:Diffusion; D004572:Electrolysis / Q000379:methods*; D004583:Electrons; D004867:Equipment Design; D005461:Fluorine / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D012493:Samarium / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D013696:Temperature; D014639:Vanadium / Q000737:chemistry
chemical_list: D014639:Vanadium; D002586:Cesium; D005461:Fluorine; D012493:Samarium; D010100:Oxygen