A New Phosphor Li2B4O7

Abstract

The phosphor Li2B4O7: Cu (0.03% by weight) has an effective atomic number of 7.3, which is very similar to that of tissue (7.4). This suggests that the phosphor should have excellent properties for thermoluminescent dosimetry. The phosphor prepared by a sintering method shows two glow peaks composed of a dosimetric peak at 205 degrees C and a shoulder at 120 degrees C, and a broad emission band peaking at 368 nm. The material based on the stoichiometric compound of Li2O . 2B2O3 has a good moisture resistant property. The dosimetric characteristics are as follows: (1) The sensitivity of gamma rays is about 20 times higher than that of Li2B4O2: Mn prepared by the conventional melting method. (2) The dosimetry peak of 205 degrees C fades less than 9% in intensity at 25 degrees C after 60 days in dark. (3) The TL output is linear with exposure to about 10(5) R, becoming sublinear above it. (4) The sensitivity loss caused by humidity is about 10-25% after 2-6 months of storage in air of 90% relative humidity at 25 degrees C. (5) The energy dependence of TL output for photons is flat within the limit of 10% from 40 keV to 7 MeV. (6) The light induced fading is 10% after 3 h room lighting at 1000 lux.

Thermoluminescence of SrB4O7:Dy

“…Further, the hygroscopicity can be an obstacle to prepare borates [3,4]. For instance, the procedure employed to prepare samples of copper doped lithium tetraborate [5] does not work to obtain samples of copper doped sodium tetraborate because of the higher hygroscopicity of the latter [6].…”

The optically stimulated luminescence (OSL) properties of LiF:Mg,TI, Li2B4O7:CU, CaSO4:Tm, and CaF2:MN thermoluminescent (TL) materials

“…This suggests that with more careful instrument design or with a POSL apparatus, which permits greater OSL detection efficiency, a fourfold increase in sensitivity may be possible from this factor alone. However, this material's optically-induced fading has been shown to be less than 10% after 3000 lx h of exposure to room light (Takenaga et al, 1983) or to have 85% loss of signal following a week of storage under fluorescent or tungsten lamp lighting (Driscoll et al, 1983), which is far less than has been seen in α-Al 2 O 3 :C (Moscovitch et al, 1993), indicating that the material likely has a relatively low photoionization cross section and thus OSL potential. Therefore, this experiment and associated literature review shows that the potential for this material as a low-dose OSL dosimetry substance appears to be limited, but that it may warrant further study to determine to what extent it could be useful for high-dose dosimetry applications, particularly those involving neutron fields.…”

“…In the case of Li 2 B 4 O 7 :Cu and CaSO 4 :Tm, in spite of their use in commercially-available dosemeters, and the presence of substantial published TL data (Takenaga et al, 1983;Driscoll et al, 1983;Samei et al, 1994;Sunta et al, 1994;Kearfott et al, 1995Kearfott et al, , 2000Simpkins and Kearfott, 1997;Lee et al, 2008;Nambi et al, 1974;Lewandowski et al, 1996;Lakshmanan et al, 2005;Yamashita et al, 1971;Harvey et al, 2010Harvey et al, , 2011Harvey and Kearfott, 2011a, 2011b, 2012, little published research exists documenting their OSL properties. However, CaSO 4 :Tm has been shown to produce a signal using photo-transferred thermoluminescence techniques (PTTL) techniques (Lakshmanan et al, 2005).…”

Effects of synthesis, doping methods and metal content on thermoluminescence glow curves of lithium tetraborate

“…4: The intensities of high temperature glow peak about 473-523 K are different between different synthesis and doping methods. In the literature there are reports on thermoluminescent performances of Cu, Ag, Mn and Cu with In (as co-dopant) doped LTB [19][20][21][22][23][24][25]. All of these materials gave a glow curve consisting of two glow peaks; the first one is at 383-393 K, and the second one in the range between 458 and 503 K, depending on the activator.…”