Rare earth doped inorganic crystal has been widely used as an important scintillator in several technologies, such as high energy radiation detection and medical imaging. Recently, with the development of a next generation of time-of-flight PET (Positron Emission Tomography) scanners, it’s urgently demanded that an ultrafast scintillator with shorter decay time and more light output. For this consideration, lanthanide ions Ce³⁺ and Pr³⁺ possesing fast f-d emission doped inorganic hosts with suitable crystal field strength are thought as a kinds of promising candidates. Under this guideline, Professor Liang’s team from Sun Yat-sen University has studies the luminescence properties of Ce³⁺/Pr³⁺ doped LiCaBO₃ phosphor in detail. And their research has been published in Journal of Materials Chemistry C on August 4^th, 2015.

(a) Crystal structure of host LiCaBO₃ and Ca²⁺ ion coordinate environment; (b) Excitation spectra of Ce³⁺/Pr³⁺ singly and doubly doped samples; (c) Analysis on energy transfer from Pr³⁺ to Ce³⁺.

The VUV-UV excitation spectra in Fig. (b) was recorded with the help of synchrotron radiation at BSRF, which provides a powerful support for studying the crystal field splitting of lanthanide ion 5d states and proving the energy transfer from Pr³⁺ to Ce³⁺.

In this work, a series of LiCaBO₃: Ce³⁺/Pr³⁺ phosphors were prepared by a high-temperature solid state reaction method. The VUV-UV excitation spectra was collected with the help of synchrotron radiation at BSRF, which provides a powerful support for studying the crystal field splitting of lanthanide ion 5d states and proving the energy transfer from Pr³⁺ to Ce³⁺. Then applying I-H (Inokuti-Hirayama) and Built-Up model, the decay curves of Pr³⁺ and Ce³⁺ was analyzed and fitting to obtain the detailed energy transfer parameters, respectively. This will offer us a deep insight into the energy transfer process between Pr³⁺ and Ce³⁺ and guide the following work on ultrafast scintillator searching.