The use of TL and OSL emissions of 3Al 2 O 3 –2SiO 2 :Er,Yb phosphors for dose rate estimation Katia Alessandra Gonc ¸alves 2 • Sonia Hatsue Tatumi 1 • Rene ´ Rojas Rocca 1 • Alexandre Ventieri 2 Received: 23 February 2015 / Published online: 20 June 2015 Ó Akade ´miai Kiado ´, Budapest, Hungary 2015 Abstract The 3Al 2 O 3 –2SiO 2 phosphors having different concentrations of erbium and ytterbium were synthetized by sol–gel technique, and thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of these samples were studied. X-ray diffraction (XRD) pat- terns of the samples confirmed the formation of the mullite crystal and revealed presence of nanocrystalline structure of erbium silicon and erbium oxide in 3Al 2 O 3 –2SiO 2 doped with Er, and ytterbium oxide nanocrystals for the Yb doped one. TL and OSL emissions parameters (trap depth, frequency factor, order of kinetics and decay constant) were evaluated by fitting the experimental curves with theoretical models. The suitability of 3Al 2 O 3 –2SiO 2 :Er; Yb for environmental radiation or in accident retrospective dosimetry has been discussed. Keywords Mullite phosphors Á 3Al 2 O 3 –2SiO 2 :Er,Yb Á Environmental dosimetry Á Accident retrospective dosimetry Á CW–OSL properties of mullite Á TL properties of mullite Introduction Silicates such as quartz and feldspar have been used in dating of sediment by the TL and OSL methods due to their luminescent response proportional to the radiation dose. Using summarized concepts, the age (A) of the sediment can be estimated by the ratio between the absorbed dose (D e = [Gy]) by the crystal over time and annual dose rate (AD = [Gy/year]) from the radioactive isotopes present in the sediment and cosmic rays contribution. Therefore, accurate dosimetry of the sediments will be always nec- essary to make an effective calculation of the AD and consequently the sediment age. This dosimetry has been done with several techniques, the most commonly used is gamma spectroscopy with a scintillation crystal, as NaI(Tl) detector or high pure Ge detector, an alternatively tech- niques are neutron activation analysis, alpha counters and Inductively coupled plasma mass spectrometry (ICP-MS). However these methods, except for NAI(Tl) portable detector, do not take into account the spatial geometry of the studied site and the contribution of cosmic radiation. Some researches in the dating area have solved these problems using TL or OSL solid state dosimeters, usually the dosimeters are placed in the sediment sampling site during several months, where they will accumulate dose from natural radioisotopes, found in the surrounding sedi- ments and from cosmic rays, then the dosimeters are col- lected and measured in the laboratory using TL or OSL emission, depend on the kind of dosimeter. Finally, the annual dose rate of this site can be evaluated dividing the accumulated dose in the dosimeters by the buried time. Nevertheless, the majority of the dosimeters provided in the current market usually have a Z eff tissue equivalent about 7.51 and therefore, it cannot be used directly in sediment sample, which is typically a mixture of clay, & Sonia Hatsue Tatumi sonia.tatumi@gmail.com Katia Alessandra Gonc ¸alves katiaale@ig.com.br 1 Departamento de Cie ˆncia do Mar, Universidade Federal de Sa ˜o Paulo, Av. Alm. Saldanha da Gama, 89, Santos, SP 11030-400, Brazil 2 Departamento de Engenharia Ele ´trica, Universidade de Sa ˜o Paulo, Av. Luciano Gualberto, 380, Sa ˜o Paulo, SP 05508-900, Brazil 123 J Radioanal Nucl Chem (2015) 306:775–780 DOI 10.1007/s10967-015-4264-5