Exploration of novel inorganic compounds using diffractometry and microscopy toward innovative functions

Abstract

The author will briefly review the recent progress and future perspective on the research topics of (i) highly c-axis-oriented polycrystals of lanthanum silicate oxyapatite in the pseudo-binary system La 2 SiO 5 La 2 Si 2 O 7 , (ii) homologous layered carbides in the system ZrYSiAlC, (iii) layered oxycarbonitrides in the system AlSiOCN, (iv) crystal structures and ordered atom arrangements in SiAlON polytypoids, and (v) disordered crystal structure of Al 3 O 3.5 C 0.5 . The crystal structures were necessarily expressed by the split-atom models for the layered oxycarbonitrides and SiAlON polytypoids, indicating that each of these compounds was composed of domains related by merohedral twinning. With Al 3 O 3.5 C 0.5 the antiphase domains (APDs) were observed, which were formed by the high-low phase transition involving loss of translational symmetry elements. The formation mechanisms of merohedral and pseudo-merohedral twin domains as well as APDs will be discussed in detail.