USE OF ACCURATE STRUCTURE DATA FROM X-RAY POWDER DIFFRACTION TO SIMULATE THE MAGNETIC PROPERTIES OF RARE EARTHS, J. Holsa, M. Lahtinen, M. Lastusaari, J. Nittykoski, R.S. Puche, J. Valkonen, pp. 98-103

The average paramagnetic susceptibilities of the RE ions in RE oxybromide powders, REOBr (RE = Ce Nd, Sm, Eu, Tb Yb), were simulated between 2 and 298 K by calculations based on the modified point charge (PCEM) model. The method used employs the detailed structure data determined from the Rietveld analyses of the X-ray powder patterns which were measured using an ordinary laboratory set-up. The results show that the Curie-Weiss behaviour of the temperature evolution of the paramagnetic susceptibility of most REOBr materials could be simulated with high reliability down to low temperatures. Even the anomalous low temperature behaviour was reproduced rather correctly for some REOBr samples. It is thus possible to obtain coherent structure data reliable enough with an ordinary laboratory X-ray diffraction set-up to be used for calculating the paramagnetic susceptibility of rare earths in solid state compounds. INTRODUCTION One of the ultimate goals in both chemistry and physics is the calculation of the chemical and physical properties of a compound both a new or an already known one by using only its structure. The success of this approach depends on several things the most important of which include the quality of the structural data as well as the quality of the model used, i.e. how realistic and complete this model is. In order to compare the results of the calculations to the actual properties of the compound, an accurate and reliable measurement of the property is essential, of course. The structural databases available to practically everybody contain nowadays a massive amount of Copyright (c)JCPDS-International Centre for Diffraction Data 2002, Advances in X-ray Analysis, Volume 45. 98