[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Using comparative methods a higher effort for the

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Using comparative methods, a higher effort for the “quantification” is neces- sary. A lot of reference materials of known composition and size need to be measured. Also some test analysis are necessary to define the best “princi- pal components” for the different specimen parameters. After that the whole procedure, the identification of the unknown material, is very fast and has sufficient reliability. Distribution Analysis If there is a possibility to analyse a small sample area then it is also possible to measure a sequence of small sample areas. These measuring points can be arranged in different patterns such as a line or a matrix (array). A distribution analysis can be performed as line scan or mapping. This offers a new dimension of information for material analysis but it does require appropriate automatic collection and data presentation procedures. Multiple Point Analysis It should be possible to arrange a pattern of measuring points on one or various samples that are placed in a sample holder. In this way, automatic measurements on large sample arrays are feasible and the sample holder may be used like a sample magazine. An interesting example is the use of micro- XRF for combinatorial chemistry [24]. This is a way to develop new materials such as catalysts, high temperature super conductors or magnetic materials,
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Methodological Developments and Applications 449 2.0 0 - 2.0 - 2.0 0 2.0 Regression factor score 1 Regression factor score 2 C3 D3 A3 E2 F2 B2 Regression factor score 1 Regression factor score 2 - 2 - 2 - 1 0 1 2 3 4 - 1 0 1 2 3 4 B2 D2 Infinit Infinit 1000 315 315 1000 100 50 0 Fig. 7.4. Plot of main components (a) for six reference glasses; (b) for two different particle composition of various sizes
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450 B. Kanngießer and M. Haschke that is, materials where the relation between material composition and sample treatment and the intended property is still not completely understood. Often a “trial and error” method for material development is necessary. Convention- ally, this will be done sequentially, that is, a new material will be generated, characterised and tested for a selected property. The procedure is iteratively repeated until the optimum performance is achieved. The procedure can be accelerated drastically if complete material banks with varying compositions are prepared instead of one composition alone. These materials may then be analysed and tested in parallel which minimises the time needed. The material bank is arranged in an array that can also be used as a sample magazine (as displayed in Fig. 7.5). However, the quantity for each specimen has to be reduced, that is, only a small volume of each sample is available but the number of samples is enhanced. These samples are analysed, either for their composition or homogeneity in order to assess the “correct” sample preparation. For the determination of the inorganic composition, micro-XRF is a very useful tool. The required amount of the sample for an analysis is small and the high sample number
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