Dielectric and microstructural properties of BaTiO₃ and Ba_0.9925Er_0.0075TiO₃ ceramics

Dielectric Properties in Transition Metal and Rare‐Earth‐Doped Multiferroic BaTiO3 Nanoparticles

“…Recently, Gong et al reported that the ferroelectric phase‐transition temperature T C of Fe‐doped (Ba,Ca)TiO 3 –Ba(Zr,Ti)O 3 ceramics decreases from 376 to 55 K corresponding to Fe concentration x from 0 to 0.30, and the sharp peaks of the DC shift to smaller broad peaks, which is characteristic of a relaxation behavior. A decrease in T C in BaTi 1− x Fe x O 3 with increasing dopant concentration x is also observed by Wei et al In rare‐earth ion (such as Ho, Er, Yb, and Lu) doped BTO, the peak of the DC and T C shift toward higher temperatures …”

“…[50] A similar increase in the dielectric function ϵ 0 with increase in the saturation magnetic field h is observed in Ni 2þ -doped BTO by Kumar et al [51] It must be noted that the phase-transition temperature T C in pure BTO also increases with increasing h. [52] In rare earth with smaller ionic radii (such as Ho, Er, Yb, Lu, and Y) doped BTO, the peak of the DC shifts toward higher temperatures because the tetragonal phase is more stable at high temperatures. [6,7] Among them, Er 3þ has been widely used due to its great technological interest. [53] It should be noted that because the size of the Er 3þ ion is almost intermediate between those of the Ba 3þ and Ti 4þ ions, it seems equally likely that Er ions occupy the site of either ions in the BTO lattice [54,55] (called amphoteric behavior) with higher preference for the Ba site.…”

“…Fe 3+ , Co 3+ , and Ni 2+ ions substitute on the Ti 4+ site and behave as acceptor dopants . Rare‐earth ions such as Ho, Er, Yb, and Lu are inserted in the Ba 2+ site . These ions act as donor dopants.…”

“…[3,4] Rareearth ions such as Ho, Er, Yb, and Lu are inserted in the Ba 2þ site. [5][6][7] These ions act as donor dopants. Magnetic properties are observed experimentally in Co-, Mn-, Cr-, and Fe-doped BTO thin films and NPs by many authors, [8][9][10][11] i.e., these materials show multiferroic properties.…”

“…A decrease in T C in BaTi 1Àx Fe x O 3 with increasing dopant concentration x is also observed by Wei et al [19] In rare-earth ion (such as Ho, Er, Yb, and Lu) doped BTO, the peak of the DC and T C shift toward higher temperatures. [6,7] There are not so many theoretical works about this problem. The effect of Fe doping in bulk BTO on structural, optical, and electronic properties is studied by density functional theory [20] and on the polarization using the defective dipole model in Monte-Carlo simulations.…”