The results of x-ray diffraction, the size of lattice parameter, and the values of oxygen diffusion coefficient in YO 1.5 -CeO 2 , GdO 1.5 -CeO 2 , and NdO 1.5 -CeO 2 systems were reviewed.In YO 1.5 -CeO 2 system, the lattice parameter decreases as the concentration of YO 1.5 increases. In GdO 1.5 -CeO 2 system, the lattice parameter does not change very much. And in NdO 1.5 -CeO 2 system, it increases as the concentration of NdO 1.5 increases.When the oxygen diffusion coefficient was plotted as a function of lattice parameter, there was no correlation between them. However, when the oxygen diffusion coefficient was plotted as a function of the concentration of trivalent cation additives, there was very good correlation between them. Consequently, the diffusion coefficient does not depend on the size of crystal lattice in ceria solid solutions, but it depends on the concentration of trivalent cation additives.

No abstract

Professor Roy authored more than seven hundreds of scientific papers in the field of geochemistry, ceramics, and materials science, which include crystal chemistry of oxides, equilibrium phase diagram, hydrothermal processing, microwave technology, sol-gel processing, diamond films, etc. In order to solve many complicated problems he realized the importance of bringing many researchers from many different fields together. He was appointed as the first director of an independent interdisciplinary Materials Research Laboratory at Pennsylvania State University in 1962, and served the position for 23 years. He then worked very hard to have Committee on the preparation for Materials Research Society. In 1973 he co-founded the pioneering interdisciplinary scientific society the Materials Research Society (MRS) and continued to advance the boundaries of science and technology up to the present. The idea of MRS expanded into other countries. Materials Research Society of Japan established in 1989 is one of these MRSs. In 1991 International Union of Materials Research Society (IUMRS) was established. It is currently very active union in the field of materials.