Synthesis and crystal structure of two new cerium rhodium oxides: Ce2/3−xRh3+2O4 (x∼0.12) with Ce mixed valency and Ce4+Rh3+2O5

The effect of the substrate on thermal stability of CeOx and Rh–Ce–O thin films

“…Recent research showed that a simultaneous radio‐frequency (RF) sputtering of CeO 2 and a noble metal can be used for deposition of thin films in a form of a solid solution . Our preliminary experiments showed that Rh–Ce–O thin films prepared by the same method contain rhodium in Rh 3+ and cerium mostly in Ce 4+ oxidation states, which is in good agreement with materials prepared by wet deposition techniques . The main interest of the present contribution is a thermal stability of the Rh–Ce–O thin films at elevated temperature.…”

“…Lately, cerium oxide doped by other oxides, such as ZrO 2 , or SiO 2 , or by a noble metal in an ionic state, drew much attention. Dopants increase the number of structural defects in cerium oxide that are directly responsible for higher oxygen storage capacity .…”

“…Furthermore, dopants prevent sintering of cerium oxide at elevated temperature because of repulsive interaction between dopant ions and thus prolong the lifetime of the catalyst . It was reported that rhodium doped cerium oxide forms a solid solution, where Rh 3+ ions substitute Ce 4+ ions of cerium oxide lattice . The material contains a substantial amount of oxygen vacancies that are necessary for maintaining a charge balance .…”

Structure and thermal stability of nanocrystalline Ce1−xRhxO2−y in reducing and oxidizing atmosphere

“…In appears that intensity of these features rather weakly depends on the temperature. The position of the reflections roughly corresponds to those of Ce 0.55 Rh 2 O 4 [23] or RhO 2 [24], but the fit is not very good (Fig. 8b).…”

“…Such effect does not appear for Rh/SiO 2 [25], but has been reported for Rh/Al 2 O 3 , where calcination at 700 8C caused formation of hardly reducible Rh(AlO 2 ) y [26]. Recently, successful synthesis of CeRh 2 O 5 and Ce 0.55 Rh 2 O 4 compounds containing Ce 4+ ions by the flux method (PbO, V 2 O 5 , NaCl) at 1000-1100 8C was reported [23]. The authors were unable however, to obtain the same products by simple reaction of the oxides, which may indicate that small amount of additives may be necessary to stabilize the structures.…”