Volume 25(1) - Winter 2009

Rigaku is pleased to announce the release of CSDA, a powerful new tool for determining average crystallite size and size distribution.

It is well known that the physical and chemical properties of nanoparticles change remarkably with variations in particle size. For this reason, methods for determining particle size are important for investigating the correlation between the particle sizes of a nanomaterial and its properties. It is frequently difficult to synthesize particles of uniform size, so it becomes necessary to evaluate not only the average size, but also the size distribution.

A “crystallite” is a small region of a solid which can be considered a single crystal, and in general, a “particle” is composed of one or more crystallites.  Therefore, “crystallite size” is normally smaller than “particle size”. The simplest method for calculating crystallite size is the Scherrer method, in which crystallite size is calculated from the width of an X-ray diffraction peak. However, the average size obtained using the Scherrer equation can be misleading, particularly when the crystallite size distribution of a sample is broad and asymmetric. CSDA overcomes this limitation by simultaneously analyzing both the width and the overall shape of a peak.
 

The Thermo plus EVO series is Rigaku’s new line of thermal analysis instrumentation, offering advanced safety features, easy operation and versatile performance.

The standard thermal analysis techniques are TGDTA, for the evaluation of heat resistance properties and component analysis of complex materials; DSC, for measuring melting, crystallization, crystalline transformation or glass transition; and TMA, for the assessment of the thermal expansions or thermal changes accompanied by change in dimension or form.  The Thermo plus EVO series provides an instrument for each of these techniques.

XtaLAB mini is a benchtop small molecule X-ray crystallography system. This chemical crystallography system is designed to produce publication quality structures automatically even though it is more compact and has lower power consumption (600 W) than its predecessor, the SCXmini. Automated processing enables less-experienced users to determine crystal structures easily. X-ray crystallographic analysis has traditionally been regarded as one of the more difficult analysis methods, but with the XtaLAB mini, X-ray crystallographic analysis becomes as accessible as NMR and IR.
 

How the effects of measurement condition influence the results

Since thermal analysis measurement is easy to be performed, anyone can obtain the same measurement result on a pre-determined measurement condition. For this reason, the use of thermal analysis is applied among analytical techniques not only in research and development but also in quality control. However, since the measurement result in thermal analysis largely depends on the measurement condition, selecting the most appropriate measurement condition with regards to the sample is important.
 

Examples for ppm to sub ppm level analysis of heavy elements

There has been a growing demand globally for the analysis of environmental hazardous substances. In Japan, The Japanese environmental regulation for a trace of zinc in wastewater has been recently revised from 5 mg/l (5 ppm) down to 2 mg/l (2 ppm).

This report introduces an X-ray fluorescence (XRF) analysis for the detection of ppb level of a trace of zinc in wastewater and also hazardous heavy elements in river water using a high sensitivity micro-droplet filter paper, “Ultracarry”, and the newly developed vacuum dryer, “Ultradry”.
 

A thin-film sample is two-dimensionally formed on the surface of a substrate, and the film thickness is usually very small, about 1 μm or less. It can be difficult to use a conventional powder diffractometer to acquire high-quality diffraction data from a thin film because thin-film diffraction peaks are usually weak, and the background intensities caused by diffraction and scattering from the substrate are very high. It is known that preferred orientation or anisotropic lattice distortion can have a strong effect on physical properties of thin films, so that it is indispensable to reveal structural or textural properties of thin films using X-ray diffraction techniques with proper X-ray optics.

A description of X-ray optics for various diffraction methods have been given in Section 2.3 of the first article in this series. Generally speaking, X-ray diffraction techniques can be divided into two groups in terms of sample geometry; “out-of-plane” diffraction or “in-plane” diffraction. Out-of-plane diffraction is the most commonly used experimental technique for studying powder, bulk and thin-film materials.

This article describes the out-of-plane diffraction measurement techniques and their applications to the determinations of crystal structures of thin films.
 

Recently, nanotechnology has made striking advances in the fabrications of nano-electronic and nano-magnetic devices. Some of the new nanostructures are nanoparticles, nanodots, nanowires, nanotubes, etc. Most of these nanostructures are often fabricated on the surface and/or at the interfaces of a thin film, and the nanostructures in many cases exhibit anisotropies along the normal and the parallel directions of the surface and interfaces.

Small-angle X-ray scattering (SAXS) technique has widely been used for the determination of structures of materials in the micrometer and nanometer ranges by measuring scattering intensities at scattered angles 2θ close to 0°. The types of structures can be determined including average particle sizes, shapes, distributions, surface to volume ratio, etc.

In order to determine anisotropic micro and nanostructures along both the normal and parallel directions in a thin film, the use of grazing incidence X-ray technique together with the small-angle scattering technique, namely grazing incidence small-angle X-ray scattering (GI-SAXS), is required.