Volume 31(1) - Winter 2015

CrystalStructure is a small molecule structure analysis software package which provides every procedure necessary in a single crystal X-ray structure analysis from determining the space group through creating CIF files.

In CrystalStructure, a “Menu bar” and a “Toolbar” are available on the main window. Necessary commands can be executed by pulling down a menu or clicking on an icon. The most distinctive feature is the “Flowbar”, which the necessary steps in a structure analysis are arranged in the sequence that you would perform them. The final result can be obtained by just running the steps in order starting at the top.

This document describes the new functions added to Crystal Structure 4.1 in its release on June 9, 2014.

Rapid data acquisition with the world’s smallest stress analyzer

X-ray stress measurement permits the non-destructive measurement of residual stress, primarily in the surfaces of metallic components or structures, and is a common measurement method for material strength, lifetime prediction and other estimations in the industrial field.

However, applications have been limited as measurement objects are often structures that cannot be brought into a laboratory, or large parts that cannot be measured due to work space limitations.

SmartSite RS can be brought to the measurement site and has made stress measurement possible even in cases as those described above. In addition, quantification of retained austenite can be performed with an optional attachment. The device is powered either by plugging into a 100–240 VAC socket or by battery, enabling measurements at various locations. Transport, even to remote sites, is easy as the entire system readily fits into the included carrying case.

A single crystal of target material is necessary to conduct single crystal X-ray structure analysis, but in an ideal single crystal, atoms and molecules have an ordered, three-dimensional repetitive structure. That is, the ideal single crystal is one in which all molecules comprising the single crystal have the same steric structure, and the geometrical arrangement of molecules within a unit cell is the same viewing from any direction. However, it is frequently the case that actual single crystals are not ideal, and there may be irregularities such as more than one molecules in an asymmetric unit, multiple crystal domains (twinning), or the disordered structure which is the topic here (disorder).

This paper starts by describing what disordered structure is, and then introduces how to determine disordered structure, and methods of refinement using the SHELX-97 structure refinement program. The author will be happy if, when the reader encounters a situation which must be analyzed as disordered structure, he or she can take their time and handle the problem, rather than giving up simply because it is a disordered structure.

There are two main sample preparation techniques for measurement of powders with XRF—pressed and loose powder methods—neither requiring any chemical processes. In either case the proper sample preparation and accessories need to be selected to prevent breakage of the pressed powder during measurement. When a thin film for analysis surface (hereafter “sample film”) or a binder is used, it is recommended to select the proper sample preparation method to minimize analysis errors of target elements. This note describes key points and considerations for sample preparation by pressed and loose powder methods. In addition, sample preparation technique for the analysis of small quantities of powder sample is introduced.

The nano3DX is an X-ray microscope with submicron spatial resolution, employing a quasi-parallel beam, near-detector system comprised of a unique high-intensity X-ray source and a high-resolution X-ray detector. By selecting the X-ray energy to that is most appropriate for the sample, the instrument is capable of observing the microstructure of various samples such as pharmaceuticals, biological tissues, organic composite materials, and electronic materials, in either 2D (X-ray photography) or 3D (computed tomography) modalities, even where the differences in the density of sample components are not significant.

The nano3DX can be used for a number of different applications, and provides various structural information. For example, the observation of a pharmaceutical tablet allows us to characterize its structural features including flacking, cracking and density distribution inside the tablet as well as the features of the coat layer including its thickness and cracking/flacking in it. With organic composite materials, one would observe the orientation of filler and fibers, peeling of the filler and/or fiber off the base material, and the distribution/orientation of voids. In observation of biological tissues, one might want to visualize the structure of small tissues or even measure their length.

While the nano3DX will provide good results using the default measurement condition, fine tuning the measurement parameters often improves the result for a specific application. This article is intended to provide the readers with a basic knowledge of X-ray absorption, X-ray projected images, and computed tomography that can be utilized to design the optimum measurement for their purposes. Actual measurement examples using the nano3DX will be given to elucidate basic principles of X-ray microscopes and how one can choose measurement parameters for obtaining high-quality data.

Various types of detectors have previously been used in X-ray diffractometers(1). Scintillation counters (SC) have been used as zero-dimensional (0D) detectors, position-sensitive proportional counters (PSPC) and semiconductor detectors as one-dimensional (1D) detectors, and devices such as imaging plates (IP) and CCD detectors as two-dimensional (2D) detectors. IP and CCD detectors are 2D detectors still in use today, but they have problems such as slow read-out speed and narrow dynamic range, and thus their applications are limited. The HyPix-3000(2) hybrid multi-dimensional pixel detector is a 2D detector with the following features not available with IP or CCD detectors.

• Wide dynamic range
• Measurement with low background
• High-speed measurement with zero dead time
• Maintenance-free

Due to the wide dynamic range, the HyPix-3000 works advantageously in cases, such as thin-film samples, where there is a need to simultaneously measure faint diffraction peaks from the film, and strong diffraction peaks from a single-crystal substrate. Since energy resolution is high, low-background measurement is possible even with samples in which the background rises due to production of fluorescent X-rays, and it is possible to acquire measurement data with an outstanding S/N ratio. In addition, the HyPix-3000 can achieve essentially zero dead time (time loss) for data read-out. By achieving this high-speed measurement with zero dead time, it is possible to carry out continuous time-slice measurement via shutterless mode operation. For example, even in in-situ measurement involving heating, it is possible to conduct measurement which follows the sample’s response such as transformation of crystal structure. Another feature of the HyPix-3000 is that it can be used without any need for troublesome maintenance such as the gas replacement required for gas detectors or the maintenance for the cooling equipment needed by CCD detectors.

In addition, by installing the HyPix-3000 in the SmartLab intelligent X-ray diffraction system, it can be used not only as a 2D detector, but also as a 0D and 1D detector. Therefore, there is no need to individually prepare each type of detector, as was done before, and go through the troublesome process of moving the sample to different detectors to suit the application. For this reason, a combined SmartLab-HyPix-3000 system (Fig. 1) can be used to measure a variety of samples, including powders, thin films and bulk samples. In addition, various measurement methods can be used to evaluate these samples, such as 2θ/θ measurement, and pole figure measurement employing a 2D detector. This paper introduces examples of measuring powder, single-crystal, bulk and thin-film samples by actually using this system.

Incandescent light bulbs lit the 20th century but the 21st century will be lit by LED lamps—thanks to discoveries recognized by the Swedish Academies of Science

On October 7th, 2014, the Royal Swedish Academy of Sciences announced that the 2014 Nobel Prize in Physics will be awarded to the three Japanese professors, Dr. Isamu Akasaki at Meijo University, Dr. Hiroshi Amano at Nagoya University, and Dr. Shuji Nakamura at University of California, Santa Barbara, for “the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources”.

The advent of the white light source according to the practical application of blue light emitting diodes (LED) brings great benefit to mankind, in the form of home lighting, display devices such as public signals, display backlighting, etc. Conventional white light bulbs create light by heating filaments, making them glow with a low conversion efficiency. Instead, an LED utilizes the recombination of electrons and holes, with good energy conversion efficiency for changing the electric power directly into light. The efficiency of this white light creation is promising for energy saving, as well as its longer-lasting nature. It is also favorable for human health and is environmentally friendly since it does not contain hazardous elements, such as mercury. The blue LED was the final technology necessary for practical white light LED-based illumination based on the triad of red, green and blue LEDs. Red and green LEDs have been available for almost half a century but creation of an effective blue LED has been an elusive challenge for many decades.