Large-scale synthesis of Ce x La 1x F 3 nanocomposite scintillator materials† Russell K. Feller, a Geraldine M. Purdy, a Denisse Ortiz-Acosta, a Sy Stange, b Andy Li, b Edward A. McKigney, b Ernst I. Esch, b Ross E. Muenchausen, c Robert Gilbertson, d Minesh Bacrania, b Bryan L. Bennett, c Kevin C. Ott, a Leif Brown, e Clay S. Macomber, a Brian L. Scott a and Rico E. Del Sesto * a Received 30th November 2010, Accepted 5th February 2011 DOI: 10.1039/c0jm04162a Transparent nanocomposites have been developed which consist of nanocrystals embedded in an organic matrix. The materials are comprised of up to 60% by volume of 7–13 nm crystals of the phosphor Ce x La 1x F 3 , and are greater than 70% transparent in the visible region at a thickness of 1 cm. Consistencies of the nanocomposites range from a solid polymer to a wax to a liquid, depending on the workup conditions of the nanoparticle synthesis. These transparent nanophosphor composite materials have potential applications in radiation detection as scintillators, as well as in other areas such as imaging and lighting, and can be produced on large scales up to near-kilogram quantities at near ambient conditions, much lower in temperature than typical nanoparticle syntheses. Introduction The applications of phosphor materials currently encompass displays, sensors and lighting, among many others. These applications rely heavily on the optical properties of the mate- rials, and thus single-crystalline or monolithic glassy materials are often required to ensure optical transparency. For scintillator applications, large single crystals are typically used because they provide the densities sufficient to ensure high stopping power towards the incident radiation, along with the requisite optical purity. However, the sizes attainable by current crystal-growth techniques are limited to several cubic centimetres, and the costs required to grow and handle a large crystal increase significantly with size. Recent advances have led to much larger crystal sizes of scintillator materials such as NaI:Tl, but the handling of these hygroscopic materials, as well as the risk of cracking and thus introducing defects, will remain challenges for some time. In contrast, polycrystalline and amorphous powders of luminescent materials are somewhat limited in applications because they naturally scatter the light that is emitted from the luminescent sites contained within. Transparent organic polymers alone have been used as plastic scintillators, but they do not exhibit the density or stopping power necessary for efficient detection of incident radiation. 1 An attractive alternative strategy for producing transparent phosphor materials on large scales is through the development of nanocomposites, which consist of nanoparticles embedded in a transparent matrix. Calculations predict that Rayleigh scat- tering decreases, and therefore optical attenuation lengths increase, exponentially as the particle size is decreased into the nanometre regime. 2 Optical attenuation lengths are predicted to be greater than 1 cm for composite materials having nanoparticle diameters below about 10 nm, suggesting that blocks of highly loaded, transparent nanocomposites several cm to hundreds of cm thick may be practical. Ideal nanophosphor composite materials would incorporate high loadings of an optically active component, but maintain transparency by limiting particle size and thus attenuation, and as a result improve light output. In addition, the synthesis of nanocomposites circumvents the limited scale and difficult, costly process of growing large, defect- free single crystals of comparable optical quality. Nanoparticles embedded in an organic matrix are also more resilient to air and moisture, and will resist the ‘‘fogging’’ often observed in many moisture-sensitive single crystalline scintillator materials. As composites, these materials can also be readily molded and shaped, which allows for flexibility in detector geometry and thus optimization of light collection. Another advantage is the prep- aration of thin films for imaging techniques, which cannot be attained with large single crystals. All of these factors make nanocomposites of this type very promising materials for use in large-scale, high-resolution radiation detectors. 2–4 a Materials Chemistry, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM, 87544, USA. E-mail: ricod@lanl.gov; Fax: +1 505-667-9905; Tel: +1 505-665-9087 b Safeguards Science and Technology, Nonproliferation Division, Los Alamos National Laboratory, Los Alamos, NM, 87544, USA c Structure Property Relations, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87544, USA d Polymers and Coatings, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87544, USA e Chemical Diagnostics and Engineering, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM, 87544, USA † Electronic supplementary information (ESI) available: Sample composition and doping levels, thermogravimetric analysis, and powder X-ray diffraction of calcined and uncalcined samples. See DOI: 10.1039/c0jm04162a 5716 | J. Mater. Chem., 2011, 21, 5716–5722 This journal is ª The Royal Society of Chemistry 2011 Dynamic Article Links C < Journal of Materials Chemistry Cite this: J. Mater. 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