X-ray scintillator Gd2O2S:Tb3+ materials obtained by a rapid and cost-effective microwave-assisted solid-state synthesis

• Published in: Journal of alloys and compounds 2019-03, Vol.777, p.638-645
• Main Authors: Machado, Ian Pompermayer, Teixeira, Verônica Carvalho, Pedroso, Cássio Cardoso Santos, Brito, Hermi Felinto, Rodrigues, Lucas Carvalho Veloso
• Format: Article
• Language: English
• Subjects: Gd2O2S:Tb3; Microwave-assisted solid-state synthesis; Synchrotron radiation; X-ray scintillation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.10.348

In this work, the microwave-assisted solid-state (MASS) synthesis is reported as a rapid, cost-effective and environmental-friendly way to prepare Gd2O2S:Tb3+ X-ray scintillation standards. The preparation procedure employs active charcoal as the microwave susceptor, using a domestic microwave oven without a setup for special gases. The MASS method drastically reduced the synthesis time and energy consumption (up to 97% in nominal power) over previous reports using conventional solid-state methods. A single-step synthesis of 10 min is enough to yield highly crystalline powders starting from Gd2O3 and Tb4O7 precursors and elemental sulfur. In order to obtain 100% pure materials with superior scintillation efficiency, two microwave treatments of 25 min each are required. Due to the reducing CO atmosphere generated in situ by the active charcoal during the microwave synthesis, no Tb4+ impurity was found according to Synchrotron Radiation X-ray Absorption (SR-XAS) experiments. Spectroscopic studies were carried out using SR Vacuum-Ultraviolet (VUV) photoluminescence and SR X-ray Excited Optical Luminescence (XEOL). The material prepared by two-step synthesis exhibited a better scintillation performance owing to higher crystal purity and emission intensity, presenting versatility for technological applications such as X-ray imaging and scintillation bio-probing. [Display omitted] •Gd2O2S:Tb3+ scintillators prepared by a cost-effective, environmental-friendly method.•Rapid microwave conversion: 96% Gd2O2S phase formation in just 10 min of synthesis.•Eu3+ impurity emission only relevant when Gd2O3 spurious phase is present.•Synchrotron Radiation XEOL/VUV spectroscopy related to structural characterization.•Efficient green scintillator fabricated with 97% reduction of power consuming.