Positron annihilation spectroscopic studies of multiferroic Bi1-xPrxFeO3 nanocrystalline compounds

[摘要] Positron lifetime (PL) and coincidence Doppler broadening spectroscopic (CDBS) experiments were carried out on BiFeO3samples doped with Pr(in place of Bi) in concentrations (x) = 0, 0.05, , 0.35. In the initial stages of doping, the existing Bi3+vacancies are occupied by Pr3+ions and positron trapping is reduced. From x = 0.15 to 0.35, more number of positrons diffused to the surfaces of the nanocrystallites. The CDBS ratio curves showed enhancement of the peak at pL= 10.2×10-3m0c due to positron annihilation with the 2p electrons of oxygen. It suggested increased trapping of positrons in newly created cationic vacancy-type defects due to the mismatch of ionic radii of Pr3+substituting Bi3+ions. The lattice parameters decreased (3.9661-3.9248Å) while the nanocrystallitesizes reduced and increased (28.6-34.2nm) during the doping.

[发布机构] School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala; 686560, India^1;Department of Physics, Devamatha College, Kuravilangad, Kottayam, Kerala; 686633, India^2;International and Inter University, Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala; 686560, India^3;Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata; 700064, India^4

[效力级别] 化学

[关键词] Cationic vacancy;Coincidence doppler broadening;Ionic radius;Multiferroics;Nanocrystalline compounds;Positron lifetime;Positron trapping;Spectroscopic studies