title: Effect of the chemical impurities on the luminescence emission of natural apatites.
abstract: This paper reports on both cathodoluminescence (CL) and blue thermoluminescence (TL) emission of well-characterized natural Spanish and Brazilian apatites [Ca5(PO4)3(OH, F, Cl)]. Chemical analyses performed by means of Electron Microprobe Analysis (EMPA) have shown the presence of trace elements that can induce CL bands. In this sense, the apatites shown emission bands peaked at 3.26, 2.86, 2.62, 2.14, 2.02 and 1.94eV are respectively linked to substitutional Ce(3+), Tb(3+), Dy(3+), Pr(3+), Sm(3+) and Mn(2+) in structural Ca(2+) positions. The 3.18eV emission band can be associated with intrinsic electron defects on oxygen of the phosphate group (PO4)(3-). The presence of (UO2)(2+) gives rise to an emission at 2.14eV. All the studied aliquots exhibit one single UV-blue TL peak that modifies the position from one sample to another (370, 256 and 268°C) probably due to (i) the variation in the crystallinity index (from 0.88 to 1.34) and (ii) successive chemical processes such as oxidation, dehydration, dehydroxylation, and fluorine ions losses due to the thermal readout.
authors.affiliation: CICATA-IPN, Legaria 694, 11500 México D.F., Mexico; CIEMAT, Av. Complutense 22, 28040 Madrid, Spain. Electronic address: holand_jeos@hotmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Roman-Lopez
authors.affiliation: CIEMAT, Av. Complutense 22, 28040 Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Correcher
authors.affiliation: Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, Madrid 28006, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Garcia-Guinea
authors.affiliation: CIEMAT, Av. Complutense 22, 28040 Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Prado-Herrero
authors.affiliation: CICATA-IPN, Legaria 694, 11500 México D.F., Mexico.
authors.forename: T
authors.initials: T
authors.lastname: Rivera
authors.affiliation: CICATA-IPN, Legaria 694, 11500 México D.F., Mexico.
authors.forename: I B
authors.initials: IB
authors.lastname: Lozano
mesh_terms: D001031:Apatites / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D028581:Lanthanoid Series Elements / Q000032:analysis; D049449:Luminescence; D008163:Luminescent Measurements; D008345:Manganese / Q000032:analysis; D013059:Spectrum Analysis, Raman; D014501:Uranium / Q000032:analysis; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D028581:Lanthanoid Series Elements; D008345:Manganese; D014501:Uranium; D002118:Calcium
keywords: Blue-thermoluminescence; Cathodoluminescence; Crystallinity index; Natural apatite