Beryllium X-ray optical properties: from highly porous to the single crystal material
- Mr. Ivan LYATUN
- Mr. Ivan LYATUN (Immanuel Kant Baltic Federal University, Kaliningrad, Russia)
- Dr. Petr ERSHOV (Immanuel Kant Baltic Federal University, Kaliningrad, Russia)
- Dr. Anatoly SNIGIREV (Immanuel Kant Baltic Federal University, Kaliningrad, Russia)
- Ms. Svetlana LYATUN (Immanuel Kant Baltic Federal University, Kaliningrad, Russia)
- Ms. Elena KOZLOVA (A. A. Bochvar High-Technology Scientific Research Institute for Inorganic Materials, Moscow, Russia)
- Mr. Maxim SHEVERDYAEV (A. A. Bochvar High-Technology Scientific Research Institute for Inorganic Materials, Moscow, Russia)
- Dr. Vladimir VOLKOV (Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow, Russia)
- Dr. Alexander SEMENOV (A. A. Bochvar High-Technology Scientific Research Institute for Inorganic Materials, Moscow, Russia)
- Dr. Vladimir GORLEVSKY (A. A. Bochvar High-Technology Scientific Research Institute for Inorganic Materials, Moscow, Russia)
- Prof. Valery SAVIN (Immanuel Kant Baltic Federal University, Kaliningrad, Russia)
- Dr. Irina SNIGIREVA (European Synchrotron Radiation Facility)
Beryllium is an important material for a wide range of scientific applications due to its unique properties. Because of its low atomic number and very low absorption for X-rays, beryllium is widely used for windows of X-ray tubes and synchrotron sources, detectors and as sample holders for special X-ray spectroscopy applications. It is the best material for X-ray refractive optics, which is extensively employed at synchrotrons and X-ray free electron lasers. Beryllium lenses are able to focus high-energy radiation up to micrometer scales, allowing to solve easily different experimental problems arising at synchrotron beamlines. They are used as condensers, micro-radian collimators, low-band pass filters, high harmonics rejecters, beam-shaping elements [1-5]. Two-dimensional Be lenses are the driving force in the development of Fourier optics, coherent diffraction, and imaging techniques [6-12].
However, almost all beryllium grades, used for X-ray optics manufacturing, are sintered materials, which have inevitably internal micro- and nanograined structure and relatively high beryllium oxide (BeO) concentration. BeO forms an inhomogeneous internal structure in beryllium – each beryllium grain covered by thin BeO film which leads to strong small- and ultra-small angular X-ray scattering and losses of intensity .
In this paper, we present experimental results of the structure and X-ray optical properties studies of a wide range of beryllium types: sintered beryllium with micro- and nano-grain structure (US and RF production), beryllium dihydride (BeH2) and extreme Be form – highly porous beryllium. The obtained results were carefully compared. The influence of the beryllium microstructure on the optical properties of the compound refractive lens was studied and successfully demonstrated for the first time in the coherent transmission X-ray microscopy mode. The direct dependence of the image quality on the average beryllium grain size was found. It allowed us to make recommendations for the use of the nano-grained beryllium as the main material for fabrication of X-ray optics for imaging applications.
In addition, a new promising material for X-ray optical applications was proposed - highly porous beryllium. Due to its low density and high porosity, this material allows manipulating the spatial coherence length, thereby changing the effective source size and removing the undesirable speckle structure in X-ray imaging and microscopy experiments with almost no attenuation of the beam .
We are confident that these new beryllium materials are very promising for imaging techniques and this will allow us to use the full potential of novel coherent X-ray sources.
Acknowledgments. This research was supported by Ministry of Education and Science of the Russian Federation (contract № 14.Y26.31.0002, 16.4119.2017/PCh).
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