Crystal Structure Refinement and Stability of LaFexNi1−xO3Solid Solutions

✍ Scribed by H. Falcón; A.E. Goeta; G. Punte; R.E. Carbonio

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 294 KB
• Volume: 133
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7477

✦ Synopsis

The crystal structure refinement of LaFe x Ni 1 \ x O 3 (04 4x 4 41) solid solutions was determined and analyzed by means of Rietveld refinement from X-ray powder diffraction data. The solid solutions with 04 4x < 0.5 are isostructural with LaNiO 3 and crystallize in the rhombohedral system, space group R3 c, while those with composition 0.5 < x4 41 are isoestructural with LaFeO 3 and crystallize in the orthorhombic system, space group Pnma. All of the solutions are single phase except that with the intermediate composition (x ‫؍‬ 0.5), where both phases are observed. The cell volume increases with the iron content. This can be ascribed to the larger ionic radius of Fe 3؉ (HS) compared to Ni 3؉ (LS). LaFe 0.25 Ni 0.75 O 3 was found to be single phase when prepared at temperatures as high as 1000°C, indicating an increase in the stability of the perovskite phase at high temperatures when a relatively small amount of iron is substituted for Ni in LaNiO 3 .