Semiconductor x-ray detectors are widely used in experiments at synchrotron facilities. The performance of these detectors depends heavily on the semiconductor material properties. Improvements in crystal growth and device processing are key to developing “high-Z” (high atomic number) semiconductors for hard x-ray detection. Germanium is the most mature high-Z semiconductor and is widely used in x-ray detectors, but it has the drawback of needing to be cooled during operation, often to cryogenic temperatures. Compound semiconductors with wide bandgaps can be used at room temperature, but crystal defects can degrade their performance. Gallium arsenide currently shows poorer energy resolution, but its comparative robustness and stability over time make it a strong option for imaging detectors. Cadmium telluride and cadmium zinc telluride both provide higher detection efficiencies at extreme x-ray energies as well as good energy resolution; the main challenge with these materials is maintaining consistent behavior under a high x-ray flux.

Indirect detection is a versatile way to detect hard x-rays. It is based on an x-ray-to-light converter, optical coupling, and a visible light detector. The converter screen, known as a scintillator, is deployed in both imaging and point detection, using either signal integration or counting. Two applications are explored in this review—sample examination and x-ray beam diagnostics for synchrotron sources. A large variety of scintillators are available to fulfill the needs of synchrotron applications. High dynamic range, small pixel size, and radiation hardness are the major advantages of scintillators. This article provides a review of the technical and scientific aspects of scintillators used in synchrotron radiation (i.e., storage rings and x-ray free-electron lasers). The advantages and drawbacks of implementation of the most popular scintillators on synchrotron beamlines are described.

We demonstrate the tungsten disulfide (WS2) thin film catalysts prepared by the sulfurization of vacuum deposited WO3 thin films for efficient hydrogen production with over 90% Faradaic efficiency. The 23-nm-thick WS2 thin film catalyst heterojunction with p-type silicon photocathode could exhibit a photocurrent density of 8.3 mA/cm2 at 0 V versus a reversible hydrogen electrode (RHE), a low onset potential of 0.2 V versus RHE when photocurrent density reaches −1 mA/cm2 and long-term stability over 10 h. The enhanced catalytic activities of WS2/p-Si photocathodes compared with the bare p-Si photocathode originate from a number of edge sites in the synthesized polycrystalline thin films, which could act as hydrogen evolution catalyst.

The use of crystals other than silicon for x-ray optics is becoming more common for many challenging experiments such as resonant inelastic x-ray scattering and nuclear resonant scattering. As more—and more specialized—spectrometers become available at many synchrotron radiation facilities, interest in pushing the limits of experimental energy resolution has increased. The potentially large improvements in resolution and efficiency that nonsilicon optics offer are beginning to be realized. This article covers the background and state of the art for nonsilicon crystal optics with a focus on a resolution of 10 meV or better, concentrating on compounds that form trigonal crystals, including sapphire, quartz, and lithium niobate, rather than the more conventional cubic materials, including silicon, diamond, and germanium.

The development of new materials and improvements of existing ones are at the root of the spectacular recent developments of new technologies for synchrotron storage rings and free-electron laser sources. This holds true for all relevant application areas, from electron guns to undulators, x-ray optics, and detectors. As demand grows for more powerful and efficient light sources, efficient optics, and high-speed detectors, an overview of ongoing materials research for these applications is timely. In this article, we focus on the most exciting and demanding areas of materials research and development for synchrotron radiation optics and detectors. Materials issues of components for synchrotron and free-electron laser accelerators are briefly discussed. The articles in this issue expand on these topics.

Refraction through curved surfaces, reflection from curved mirrors in grazing incidence, and diffraction from Fresnel zone plates are key hard x-ray focusing mechanisms. In this article, we present materials used for refractive x-ray lenses. Important properties of such x-ray lenses include focusing strength, shape, and the material’s homogeneity and absorption coefficient. Both the properties of the initial material and the fabrication process result in a lens with imperfections, which can lead to unwanted wavefront distortions. Different fabrication methods for one-dimensional and two-dimensional focusing lenses are presented, together with the respective benefits and inconveniences that are mostly due to shape fidelity. Different materials and material grades have been investigated in terms of their homogeneity and the absence of inclusions. Single-crystalline materials show high homogeneity, but suffer from unwanted diffracted radiation, which can be avoided using amorphous materials. Finally, we show that shape imperfections can be corrected using a correction lens.

The Magnetoelectric (ME) effect has been observed in single phase hexaferrite bulk and thin films of SrCo2Ti2Fe8O19. In this paper we demonstrate that the ME linear coupling depends strongly on the Co ion concentration relative to the Ti ion concentration exhibiting extremum points at a concentration consistent with above formula. The Alternating Target Laser Ablation Deposition technique was utilized to deposit ME hexaferrite films for the first time. This allows for the deposition of transition metal ions at specific sites in the basic unit cell of the hexaferrite.

Pulsed electric current sintering offers rapid sintering of many materials compared with hot press sintering. Earlier studies had demonstrated that neither sparks nor plasma formation occur in a typical apparatus such as Dr. Sinter™. Hitchcock et al. showed that electromagnetic radio frequency (rf) emission occurred during the pulsing current and suggested this emission was a relevant augmentation to the hot press sintering in addition to the current flow in the specimen. In this report the importance of rf emission in the sintering process is demonstrated and opportunities to further exploit this approach to improve the sintering process are suggested.

SiNx films were grown by plasma-enhanced chemical vapor deposition on Si substrates with the composition controlled by the flow ratio R: ammonia to silane in the range R = 0.45–1.0. Then SiNx films were annealed at 1100 °C for 30 min to form Si-quantum dots (QDs). Fourier transform infrared spectroscopy study permits estimating SiNx compositions. Photoluminescence (PL) spectra of SiNx films included bands peaked at: 2.87–2.99, 2.42–2.54, 2.10–2.25, and 1.47–1.90 eV. Former three PL bands are attributed to emission via defects in SiNx films. Fourth PL band is assigned to exciton emission in Si QDs, detected by transmission electron microscopy study in films grown at R ≤ 0.67. The nature of non-radiative defects in SiNx films is discussed as well.