Thermoluminescence of CaF₂(Eu): influence of the presence of other lanthanide impurities

CaF 2 (EU) is known to be a poor thermoluminescent (TL) phosphor. This is attributed to the high stability of Eu 2+ against oxidation/reduction upon irradiation/heating. This Letter demonstrates a new possibility of achieving considerable reduction of Eu 2+ ions in CaF 2 (Eu) upon irradiation, in the presence of other lanthanide ions such as Ce 3+ , Dy 3+ and Ho 3+ , this also leads to a greater than tenfold increase in the TL sensitivity of otherwise pure CaF 2 (Eu) with the TL emission still coming mainly from Eu 2+ ions. The possible role played by the other trivalent lanthanide ions in the reduction of Eu 2+ upon irradiation is discussed.