Investigations of optical and scintillation properties of Tm3+-doped YAlO3

Pure, 0.1, 0.5 and 1 mol% Tm-doped YAP single crystalline scintillators were grown by the μ-PD method. Lattice constants were gradually decreased with Tm concentration in XRD analysis. In transmittance measurement, absorption bands due to Tm
³⁺
4f-4f transitions were observed at 265, 360, 485, 690 and 800 nm and they were ascribed to the transition from the
³
H
₆
ground state to its excited states,
¹
I
₆
,
¹
D
₂
,
¹
G
₄
,
³
F
₃
and
³
H
₄
, respectively. Strong emission peak due to 1I6-3F4 transition of Tm
³⁺
was shown at 350 nm under X-ray irradiation. Photoluminescence decay time constants caused by this transition were evaluated to be from 15.3 to 17.3 μs and the scintillation decay time constants under gamma-ray excitation were estimated to be from 17.5 to 18.8 μs. Tm 1% doped one exhibited the highest light yield of 15100 ± 1500 photons/MeV when excited by
¹³⁷
Cs gamma-ray irradiation.