Surface Structure and Electronic Properties of Lu3Al5O12

Lu3Al5O12 (LuAG) is a famous scintillator that has the advantages of high efficiency, high light yield, and fast decay after being doped with active ions. F centers (oxygen vacancies with two electrons) and antisite defects are the most important defects and can greatly affect the scintillation performance in the bulk materials. However, the surface defects that strongly affect the spectrum of a single crystal (SC) and single crystal film (SCF) and the effect on the electronic properties have not been investigated. In this context, we investigate the surface structural and electronic properties of Lu3Al5O12 using first-principles calculations. The Lu atoms are six-fold and seven-fold coordinated with the O atoms on the S1 and S2 surfaces. The surface oxygen vacancies and antisites have considerably lower formation energies than for the bulk. The oxygen vacancies in the bulk introduce the occupied states in the band gap. The surface electronic states are mainly located on the oxygen atoms and can be eliminated via oxygen vacancies

LuAG ceramic scintillators for future HEP experiments

Because of its bright and fast scintillation cerium-doped Lu₃Al₅O₁₂ (LuAG:Ce) crystals have attracted an interest in the high energy physics community. Compared to inorganic crystals, fabrication of ceramic scintillators features with a lower temperature and a more effective use of raw materials, thus promising cost-effective inorganic scintillators. Our investigations revealed excellent radiation hardness of LuAG:Ce ceramics in both transmittance and light output against an ionization dose up to 200 Mrad and a proton fluence up to 3×10¹⁴ p/cm². We also investigated light output and decay kinetics for LuAG:Ce ceramics with different Ce doping levels and various co-dopings. The results show increased light output and slow scintillation component when the Ce doping level increases. Ca²⁺ co-doping is found effective in suppressing slow scintillation component in LuAG:Ce ceramics. We also discuss the status of LuAG ceramic scintillators and future development plan

LuAG ceramic scintillators for future HEP experiments

Because of its bright and fast scintillation cerium-doped Lu₃Al₅O₁₂ (LuAG:Ce) crystals have attracted an interest in the high energy physics community. Compared to inorganic crystals, fabrication of ceramic scintillators features with a lower temperature and a more effective use of raw materials, thus promising cost-effective inorganic scintillators. Our investigations revealed excellent radiation hardness of LuAG:Ce ceramics in both transmittance and light output against an ionization dose up to 200 Mrad and a proton fluence up to 3×10¹⁴ p/cm². We also investigated light output and decay kinetics for LuAG:Ce ceramics with different Ce doping levels and various co-dopings. The results show increased light output and slow scintillation component when the Ce doping level increases. Ca²⁺ co-doping is found effective in suppressing slow scintillation component in LuAG:Ce ceramics. We also discuss the status of LuAG ceramic scintillators and future development plan

Optical properties of Er, Yb co-doped YAG transparent ceramics

The transparent polycrystalline erbium and ytterbium co-doped yttrium aluminum garnet (Er, Yb:YAG) ceramics with various Yb contents from 5% to 25% were prepared by the solid-state reaction and the vacuum-sintering technique. The in-line transmittances of the mirror-polished ceramics exceed 80% from the visible band to the infrared band. The samples are very compact with few pores. The average grain size of the Er,Yb:YAG ceramic is about 15 mu m. The upconversion luminescence spectra, infrared luminescence spectra and luminescence decay curves of the ceramics were observed and discussed. For 1%Er doped YAG ceramic, the best ion ratio of Yb(3+) and Er(3+) is around 15:1. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Preparation and Optical Properties of Infrared Transparent 3Y-TZP Ceramics

In the present study, a tough tetragonal zirconia polycrystalline (Y-TZP) material was developed for use in high-speed infrared windows and domes. The influence of the preparation procedure and the microstructure on the material’s optical properties was evaluated by SEM and FT-IR spectroscopy. It was revealed that a high transmittance up to 77% in the three- to five-micrometer IR region could be obtained when the sample was pre-sintered at 1225 °C and subjected to hot isostatic pressing (HIP) at 1275 °C for two hours. The infrared transmittance and emittance at elevated temperature were also examined. The in-line transmittance remained stable as the temperature increased to 427 °C, with degradation being observed only near the infrared cutoff edge. Additionally, the emittance property of 3Y-TZP ceramic at high temperature was found to be superior to those of sapphire and spinel. Overall, the results indicate that Y-TZP ceramic is a potential candidate for high-speed infrared windows and domes

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders