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

抄録

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 La₂SiO₅–La₂Si₂O₇, (ii) homologous layered carbides in the system Zr–Y–Si–Al–C, (iii) layered oxycarbonitrides in the system Al–Si–O–C–N, (iv) crystal structures and ordered atom arrangements in SiAlON polytypoids, and (v) disordered crystal structure of Al₃O_3.5C_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 Al₃O_3.5C_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.