W. W. van den Hoogenhof

Note on the crystal structure of the ternary rare earth-3d transition metal compounds of the type RT4Al8

Abstract The occurrence and crystal structures of ternary compounds of the composition RT 4 Al 8 (T = V, Cr, Mn, Fe, Co, Ni or Cu, R = rare earth, Y or Th) have been investigated. The various effects of the atomic sizes are discussed.

Total reflection X-ray fluorescence of single and multiple thin-layer samples

Abstract In Total-reflection X-Ray Fluorescence (TXRF) the penetration depth of the exciting X-rays can be varied between a few nanometers and a few micrometers. In this paper the extension of the application of this technique to thin-film analysis is studied. First a theory is described with which the angular dependence of TXRF intensities can be calculated. Next calculated data are shown for various thin-film samples. The theoretical results compare favourably with preliminary experiments performed with a modified diffractrometer equipped with an energy-dispersive X-ray detector. The conclusion is that TXRF, especially when combined with X-ray reflectivity measurements, is a promising technique to obtain information about quantity and distribution of material over the various layers. The expected detection limits for this case are of the order of 10 13 atoms cm −2 .

Glancing-incidence X-ray analysis

Abstract The ever-increasing interest in ever-decreasing structural details of materials has led to specialized methods such as total-reflection X-ray fluorescence spectrometry (TXRF). Combining the angular dependence of TXRF with reflectivity experiments in the same instrument opens the field of glancing incidence X-ray analysis (GIXA), which offers the possibility for detailed analysis of flat (layered) samples. In this paper, the various types of measurement are described and their information content is discussed. Furthermore, the role of interface roughness is indicated. With some examples it is shown how the complementary data yield a detailed analysis of a sample.

The crystal structures of Eu3Ag2, EuAg and EuCu

Abstract The crystal structures of the compounds Eu3Ag2, EuAg and EuCu were determined by means of X-ray diffraction on powder samples. The compound Eu3Ag2 crystallizes in the tetragonal U3Si2 structure. The lattice constants are a = 8.461 A and c = 4.515 A . The compound EuAg crystallizes in the orthorhombic FeB structure. The lattice constants are a = 8.037 A , b = 4.764 A and c = 6.259 A . The crystal structure of the compound EuCu was found to be isotypic with that of EuAg. For EuCu the lattice constants are a = 7.980 A , b = 4.424 A and c = 6.049 A .

The profile of layered materials reflected by glancing-incidence X-ray analysis

Specular reflectivity, diffuse scattering at glancing incidence and angle-dependent total-reflection X-ray fluorescence are complementary techniques for the investigation of layered materials. The principles of these glancing-incidence X-ray methods are briefly discussed. Examples show the strength of the combination of these techniques.

Note on the formation and the magnetic properties of amorphous Eu-Ag alloys

Abstract Results are reported of an investigation of several amorphous alloys of Eu and Ag made by melt spinning. The crystallization temperatures were determined by differential scanning calorimetry. By means of magnetic measurements it was established that the Eu ions are divalent in all amorphous Eu-Ag alloys. In order to compare the magnetic coupling in the amorphous alloys with that in crystalline compounds, an investigation was also made of the magnetic properties of the compounds Eu 3 Si 2 (tetragonal, U 3 Si 2 -type) and EuAg (orthohombic, FeB-type). Their magnetic properties and lattice constants are given together with those of the compounds EuAg 2 and EuAg 5 .

Effect of interfacial-roughness replication on the diffuse X-ray reflection from periodical multilayers

The correlation of roughness profiles of different interfaces in a periodical multilayer affects the reciprocalspace distribution of the diffusely reflected X-ray intensity. This distribution has been calculated by means of the Distorted-Wave Born Approximation (DWBA) method and compared with the results of X-ray reflectometry on periodical metallic multilayers. It has been shown that the measurement of the reciprocal-space distribution of diffusely scattered intensity is a suitable non-destructive method to investigate the roughness replication in multilayers.

Glancing-Incidence X-Ray Analysis of Layered Materials

X rays at glancing incidence can set up an X-ray Standing Wave (XSW) in layered materials. In Glancing-Incidence X-ray Analysis (GIXA), the XSW is used as a nanometric yardstick to determine depth distributions of atoms by a combination of reflectivity and x-ray fluorescence. Examples are presented and features resulting from interface roughness are discussed.