• journal_title：European Journal of Mineralogy
• Contributor：Guillaume MORIN ; Thierry ALLARD ; Etienne BALAN ; Philippe ILDEFONSE ; Georges CALAS
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2002-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2002/0014-1087
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：14
• issue：6
• firstpage：1087
• section：Articles

A native Cd⁺ centre (5s¹, S = 1/2) was detected in natural sedimentary fluorapatite using Electron Paramagnetic Resonance (EPR). The Cd⁺ centre generated by artificial X-ray irradiation of the same sample has an EPR spectrum similar to the native Cd⁺ centre but differs in its thermal stability. The artificial Cd⁺ centre exhibits fast thermal decay, i.e., t_1/2 = 380 ± 30 h at room temperature (RT), although the native centre is stable at RT. Comparison with Cd⁺ centres obtained by X-ray irradiation of synthetic Cd-doped fluorapatite samples indicates that both the native and artificial Cd⁺ centres correspond to Cd⁺ ions substituting for Ca₂₊ in the apatite structure. Comparison with other artificial Cd⁺ centres already reported in various minerals suggests that the Cd⁺ centre in the studied fluorapatite sample mainly occupies the Ca(1) site with coordination number [9]. The apparent stability of the native Cd⁺ centre is not yet explained but could be related to charge compensation.