First electron spectroscopic imaging experiments on the new JEOL 2010 FEF

The new JEOL 2010 FEF is a field emission gun TEM equipped with an Omega energy filter which is integrated in the projector lens system of the instrument. In the present study, the performance of the instrument in the analysis of elemental distributions by means of electron spectroscopic imaging was evaluated. Two systems were chosen: (i) Ca-doped Si₃N₄ ceramics, in which the Ca segregation in the grain boundary films and triple junctions was investigated, and (ii) the 27R polytypoid in Al₉O₃N₇, in which an attempt to image the chemical modulation of the oxygen content within the structural unit cell was made. The results on the Si₃N₄ ceramics prove that Ca shows a strong tendency to segregate to the interface between the amorphous oxide phase and the Si₃N₄ grains. Our findings support the model of an electrical double layer giving rise to the dissipative force which widens the grain boundary film thickness with increasing Ca-content. In the Al₉O₃N₇ material the expected modulation of the oxygen content with a periodicity of 2.4 nm could be verified by electron spectroscopic imaging. It can be concluded that oxygen partly segregates to the planar inversion domain boundaries, whereas the remainder of the oxygen content is homogeneously distributed on the anion sites.