Phase relations and high temperature-XRD studies of Gd2−xNdxTi2O7 solid solutions

✍ Scribed by B.P. Mandal; A.K. Tyagi

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 266 KB
• Volume: 136
• Category: Article
• ISSN: 0921-5107
• DOI: 10.1016/j.mseb.2006.08.053

✦ Synopsis

A series of compositions with the general formula Gd 2-x Nd x Ti 2 O 7 (0.0 ≤ x ≤ 2.0) was prepared by ceramic sintering and characterized by powder XRD. Nd 3+ has been used as a surrogate for Am 3+ , an actinide found in spent nuclear fuel. One end member, Gd 2 Ti 2 O 7 , had the pyrochlore structure and formed solid solutions with Nd 2 Ti 2 O 7 up to the nominal composition Gd 1.2 Nd 0.8 Ti 2 O 7 . An increase in lattice parameter was observed as a function of x in the series Gd 2-x Nd x Ti 2 O 7 in the composition range 0.0 ≤ x ≤ 0.8. Compositions Gd 2-x Nd x Ti 2 O 7 in the range 0.8 ≤ x ≤ 1.4 were biphasic. From x ≥ 1.6, the solid solutions are monoclinic, isotypic with Nd 2 Ti 2 O 7. These results were explained based on the radius (r A /r B ) ratio of the cations. High temperature-XRD studies on cubic pyrochlores showing thermal expansion are reported.