Irradiation-induced amorphization of Cd{sub 2}Nb{sub 2}O{sub 7} pyrochlore
Several investigations have recently been undertaken in order to achieve a more complete understanding of the radiation-damage mechanisms in A{sub 2}B{sub 2}O{sub 7} pyrochlore-structure compounds. The present work represents the first systematic study of the irradiation-induced amorphization of a pyrochlore with A- and B-site cation valences of +2 and +5, respectively. Relatively large single crystals of Cd{sub 2}Nb{sub 2}O{sub 7} were grown for these experiments. In situ ion-irradiation experiments were carried out in a transmission electron microscope in conjunction with ex situ Rutherford backscattering measurements of ion-irradiated Cd{sub 2}Nb{sub 2}O{sub 7} single crystals. Cd{sub 2}Nb{sub 2}O{sub 7} can be amorphized in situ by Ne or Xe ions at temperatures up to 480 and 620 K, respectively. At room temperature, the amorphization fluence was 36 times higher for 280 keV Ne{sup +} than for 1200 keV Xe{sup 2+}, corresponding to a displacement dose that was higher by a factor of 3. Disordering of Cd and Nb over the available cation sites occurs at intermediate ion doses prior to amorphization. The temperature dependence of the amorphization dose is modeled, and the results are compared to those of a previous model. The bulk-sample Rutherford backscattering spectroscopy (RBS) results were generally consistent with the in situ TEM measurements. Effects of crystallographic orientation and ion charge state had relatively little effect on the damage accumulation in bulk crystals. The RBS data are consistent with a defect-accumulation, cascade-overlap model of amorphization of Cd{sub 2}Nb{sub 2}O{sub 7}, as are the in situ TEM observations.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40205423
- Journal Information:
- Physical Review B, Vol. 63, Issue 10; Other Information: DOI: 10.1103/PhysRevB.63.104109; Othernumber: PRBMDO000063000010104109000001; 084106PRB; PBD: 1 Mar 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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