Glass and ceramic sample

Given the wide diversity of solid sample forms and the particular difficulty of machining oxide (e.g., glass and ceramic) samples to a fixed form, rf GD ion... 

Laser sampling is more a physical phenomenon than a chemical one. The energy of the laser is used to nonselectively ablate the sample. This insures homogeneous sampling of a physically defined area regardless of the nature of the components Solubilities are not a factor. This technique shows much promise for ceramics, glasses, and geologic samples. 

Essentially all types of samples can be analyzed by this technique. Ideally, samples should be good electrical conductors to avoid charge buildup however, a very thin conducting film, for example gold or carbon, can be deposited on nonconductors such as ceramics, glasses, and biological samples. 

X-ray photoelectron spectrometry (XPS) is used to determine major and minor element compositions of metallic and ceramic surfaces. It can also be used to determine the oxidation states of ions on the surface of a sample. However, it has a limited depth penetration of 2-20 atomic layers and so the measurements taken will be greatly influenced by the method of sample preparation. The ability to characterize elements with atomic numbers less than 10, coupled with the ability to analyze samples smaller than 1.5 cm, make this technique particularly useful for the colorants and clarifying agents used in glasses and ceramics. For example, it has been used to... 

All of the systems described are now available with an incorporated differential thermal analyzer. DTA has been described in Section 16.2, so a few examples of the advantages of combining these systems will be presented. The incorporation of a DTA with one of the optical analyzers described requires the use of two thermocouples to measure the temperature difference between the sample and a reference standard (calcined kaolin or alumina). As noted, the optical noncontact instruments described are particularly useful in the glass and ceramics industries, so examples of evaluating raw materials from these industries will be described (from Paganelli and Venturelli). 

The most critical part in the van der Pauw measurement is the sample preparation, which usually is destructive to the sample and also time consuming compared to the four-point probe technique. Square-shaped samples are the most practical, especially for coatings on glass and ceramics, as they have to be cut from the normally larger samples to fulfill the requirement of a homogeneous thickness and defect free surface. Typical sample sizes are in the order of 10 x 10 mm for most commercial measurement systems. In the case of sol-gel wet coated samples, it is moreover important to take care that the circumference of the sample is not coated, but is non-conducting. 

One of the authors, PSD, expresses her sincere gratitude to Dr. H. S. Maiti, Director, Central Glass and Ceramic Research Institute, Kolkata for permission to contribute this chapter. The authors thank Dr. M. Chatterjee of CGCRI for providing the negatives of rrO samples. 

Thermal neutron activation analysis has been used for archeological samples, such as amber, coins, ceramics, and glass biological samples and forensic samples (see Forensic chemistry) as weU as human tissues, including bile, blood, bone, teeth, and urine laboratory animals geological samples, such as meteorites and ores and a variety of industrial products (166). 

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