Liqiong An

Highly transparent Nd 3+ :Lu 2 O 3 produced by spark plasma sintering and its laser oscillation

Laser oscillation was demonstrated using a 1 at.% Nd3+-doped Lu2O3 (Nd3+:Lu2O3) transparent ceramic produced by spark plasma sintering. Nd2O3, Lu2O3, and LiF commercial powders were mixed by ball milling and were sintered at 1723 K using a two-step sintering profile. After the transparent Nd3+:Lu2O3 ceramic was annealed in air, its transmittance at 1076 nm reached 81.8%, which was close to the theoretical value for Lu2O3 (82.2%). The absorption cross-section at 806 nm was 1.29 × 10−20 cm2, and the fluorescence decay time at 1076 nm was 229 μs. The laser oscillation of Nd3+:Lu2O3 ceramic for the transition from 4F3/2 to 4I11/2—specifically, at 1076.7 and 1080.8 nm—was simultaneously obtained, with a laser output of 0.21 W and slope efficiency of 14%.

Effect of LiF addition on spark plasma sintering of transparent Nd-doped Lu2O3 bodies

Abstract Transparent Nd-doped Lu2O3 bodies were fabricated by spark plasma sintering, and the effect of LiF addition on sintering, microstructure and transparency of Nd-doped Lu2O3 bodies were investigated. LiF promoted the densification at an early stage of sintering, resulted in high transparency of the Nd-doped Lu2O3 body. The optimal content of LiF was 0.2 wt% and that Nd-doped Lu2O3 body showed a transmittance of 81.8% (99.5% of theoretical) at 1080 nm after annealing in air for 21.6 ks.

Scintillation Properties of

Nd³⁺-doped Lu₂O₃ (Nd: Lu₂O₃) is a candidate for an infrared scintillator because (i) Lu₂O₃ has a high density of 9.5 g/cm³ and a high atomic number of 67 and (ii) Nd³⁺-doped materials emit in the infrared range and the emission lines from Nd³⁺ can be used in medical applications since human body has a transparency window between 600 and 1,100 nm. However, it is extremely difficult to fabricate Lu₂O₃ single crystals using conventional crystal growth methods because of the high melting point (2,510 ^° C). Using solid-state reactions, it is much easier to fabricate Lu₂O₃ into a ceramic structure. Therefore, Nd: Lu₂O₃ transparent ceramics were fabricated using a spark plasma sintering method. This technique is comparatively simple and consumes less time than other methods such as vacuum hot pressing. The scintillation properties and transmittance spectra of the as-produced ceramics were studied in both the visible and infrared regions. Radioluminescence spectra were measured in the range 800-1,200 nm. Nd³⁺ emission lines were observed in the transparency window of human body. Thus, these ceramic materials could be a candidate for medical imaging applications.

{\rm Nd}^{3+}

Detailed scintillation properties of Sc₂O₃, especially γ-ray response, are not well studied because of low density and low effective atomic number of this compound. They are reported in this paper. Sc₂O₃ single crystals grown by the micro-pulling-down method and Sc₂O₃ translucent ceramics produced by the spark plasma sintering are analyzed. Optical, luminescence, and scintillation properties of these single- and poly-crystalline solids are discussed and compared based on examination of their optical transmittance, radio-luminescence spectra, light yields under γ-ray excitation, non-proportionality, energy resolution, and scintillation decay profiles. Spectrally corrected light yields of the Sc₂O₃ single crystals and Sc₂O₃ ceramics were approximately 7,700 and 19,200 photons/MeV, respectively.