1. Enhancement of fundamental analytical technology

Gold beads obtained by fire assay analysis method

We are continuously endeavoring to improve our wet analysis methods, including titration and precipitation, and dry assay analysis methods used for analysis of gold and silver. We utilize them for rigorous quality control and the development of leading-edge products and production processes.

Fire assay analysis method

Under high temperatures, reducing agents such as iron nails and wheat flour are used to separate precious metals (primarily gold and silver) contained in a sample, which are absorbed in lead. Using the cupellation method, the lead is permeated into bone ash, from which the precious metals are extracted and weighed.

2. Development of high-sensitivity analytical technology

We are conducting ordinary analysis with a sensitivity at the ppm level or lower, making full use of state-of-the-art analyzers, such asInductively Coupled Plasma - Optical Emission Spectrometer (ICP-OES), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Flame-Less Atomic Absorption Spectrometer (FL-AAS), Gas Chromatography-Mass Spectroscopy (GC-MS) and others. We have also developed an analytical method using the ICP-MS, which is resistant to interference by external conditions, as well as being super-sensitive.

IOur approach to ICP-MS－Response to microscale analysis

Figure 1

The ICP-MS is super-sensitive and can manage a simultaneous multi-element analysis. However, this analysis equipment is said to be able to accept up to 0.1% of total salt concentration, generally approximately 0.01%. Thus, isolation of a target element for quantitative analysis from major constituents, as well as making solution of a sample, is required. Since this isolation process is cumbersome and takes considerable time, the use of the ICP-MS constitutes a problem in that it prevents speedy analysis for research and development. Consequently, we studied a method which did not require isolation technology at the pretreatment stage for samples, while optimizing the sensitivity of the ICP-MS.

We have succeeded in reducing monocular ions (collisions and reactions) by means of the implantation of a helium gas or a hydrogen gas through an inlet established on sampled cons or skimmer cons of Collision Reaction Interface (CRI), shown in Figure 1.

Under a general analysis condition (a sensitivity condition), as shown on Figure 2, coexistence of salt (here sodium chloride) reduces the sensitivity of the analyzer. However, the method using the CRI, as indicated in Figure 3, enables us to inhibit the effect of sodium chloride. As a result, the calibration curve is almost identical to that without the presence of sodium chloride.

Figure 2

Figure 3

3. Surface analysis and crystal structure analysis

We do not only observe and analyze the surfaces of substances by Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) or Electron Probe Micro Analyzer (EPMA): we also analyze the crystal structure of the substance by X-ray diffraction (XRD) and the Transmission Electron Microscope (TEM). We also conduct analyses from any aspects in a comprehensive manner using Focused Ion Beams (FIB) and Cross-section polishers (CP), to strongly support new materials development. This equipment plays an extremely important role in certain practical applications, including analyses of the interfacing of plates or mechanism studies on peel of plates.

SEM

Researchers of Technology Development Center can use SEM as well as Energy-dispersive X-ray spectroscopy (EDX) for speedy analyses of sample materials(EDX is indispensable for judging the necessity of full-scale analyses). Recently, a new system was made available for digitalized data encoding.

XPS

XPS is the only equipment capable not only of identifying elements but also of obtaining their valence number information. Ordinarily, it acquires averaged information of several hundred μmφ, and itcan acquire information of the first surface layers, locating a few nm depth from the surface, and is frequently used for depth profile analysis through a sputtering process with Ar+. Our Technology Development Center is using this equipment in a broad range of research activities including surface analyses of semiconductor materials, observation of structure of plates and confirmation of anticorrosive effects.

AES

Field emission typed electron guns can realize SEM images of up to 300 thousand magnifications, and up to several tens of thousand-power elemental analyses and mappings. AES, having an equivalent or superior analytical capability on the first surface layers to XPS, is essential for analysis of advanced devices, which are becoming increasingly thinner.

EPMA

EPMA ( EBSP )

EPMA also uses resolution field emission typed electron guns, and has an equivalent level of resolution to AES to make elemental analyses and mappings. Since its detection signal is strong enough to reach a depth of 1μm within substances, with a thin coat of carbon or platinum, observation and analysis of insulating specimens can be made. Correlation analysis made by EPMA can identify differences in chemical combination ratios of the same chemical compounds to remap them. Also, by using the Electron Back-Scanning Diffraction Pattern (EBSP) method, we can analyze crystalline orientation and conditions of the crystalline boundaries through information imparted by electrons which hit the crystals and are reflected.

XRD

This equipment is now fully controlled by personal computer, and has been available to all researchers in the Technology Development Center. A database with an enormous data capacity, and which is wholly digitalized for peak analysis, can be easily searched by the appropriate software.

TEM

TEM

This equipment’s electron gun is LaB6 and its accelerating voltage is 300kV. Observation at more than 500 thousand-fold magnification and submicron analysis is available. Since FIB enables samples to be easily sliced into thin sections, demand for the use of the TEM to observe crystal grains and precipitates has dramatically increased. TEM

FIB, CP

FIB

While most of the abovementioned analyzers observe the surfaces of substances, focused ion beams (FIB) or cross-section polishers (CP) are used to process samples so as to enable the equipment to observe and analyze cross-sections of materials. In particular, FIB combined with a secondary electron detector can cast a three-dimensional shadow of samples by piling up SEM images of samples that are ground down little by little.