Grain Boundary Mobility in Y₂O₃: Defect Mechanism and Dopant Effects

Abstract

The effects of the dopants, Mg2+, Sr2+, Sc3+, Yb3+, Gd3+, La3+, Ti4+, Zr4+, Ce4+, and Nb5+, on the grain boundary mobility of dense Y2O3 have been investigated from 1500° to 1650°C. Parabolic grain growth has been observed in all cases over a grain size from 0.31 to 12.5 μm. Together with atmospheric effects, the results suggest that interstitial transport is the rate‐limiting step for diffusive processes in Y2O3, which is also the case in CeO2. The effect of solute drag cannot be ascertained but the anomalous effect of undersized dopants (Ti and Nb) on diffusion enhancement, previously reported in CeO2, is again confirmed. Indications of very large binding energies between aliovalent dopants and oxygen defects are also observed. Overall, the most effective grain growth inhibitor is Zr4+, while the most potent grain growth promoter is Sr2+, both at 1.0% concentration.

Structural and optical properties of Tm:Y2O3 transparent ceramic with La2O3, ZrO2 as composite sintering aid

“…The Y 3+ interstitial concentration and the O 2− vacancy concentration demonstrate a positive relationship between each other in Y 2 O 3 which is presented in formula (1). 23 Therefore, the doping of Zr 4+ led to a lower concentration of Y 3+ interstitial, and hence a lower mobility of grain boundary in Y 2 O 3 ceramic.…”

“…This indicated that the La 3+ ions enhanced the mobility of grain boundary while the Zr 4+ ions strongly suppressed the migration of grain boundary, coinciding with the published literatures. 14,17,19,[20][21][22][23] Considering the Y 2 O 3 structure with one fourth of anion sites vacant, 24 the O 2− ions diffuse much faster than Y 3+ ions. Moreover, as profoundly investigated, 23,25 the diffusion of Y 3+ interstitial is ascertained to be the controlling step of sintering process in Y 2 O 3 ceramic rather than Y 3+ vacancy.…”

“…14,17,19,[20][21][22][23] Considering the Y 2 O 3 structure with one fourth of anion sites vacant, 24 the O 2− ions diffuse much faster than Y 3+ ions. Moreover, as profoundly investigated, 23,25 the diffusion of Y 3+ interstitial is ascertained to be the controlling step of sintering process in Y 2 O 3 ceramic rather than Y 3+ vacancy. In our experiment, the doping of La 3+ could induce a distortion of the lattice or a modulation of phonon vibration spectra because of a larger radius (1.061Å) than Y 3+ ion (0.9Å), which led to a faster diffusion of the Y 3+ interstitial.…”

“…In our experiment, the doping of La 3+ could induce a distortion of the lattice or a modulation of phonon vibration spectra because of a larger radius (1.061Å) than Y 3+ ion (0.9Å), which led to a faster diffusion of the Y 3+ interstitial. 23 Thus the doping of La 3+ inevitably led to a higher mobility of grain boundary. On the contrast, the doping of Zr 4+ induced a decrease of O 2− vacancy concentration because of charge compensation.…”

Investigation of emission properties of Tm3+:Y2O3 transparent ceramic

“…The average grain size was determined to be 22 µm by multiplying the average interpreting grain size with a correlation factor of 1.56 [11] . The mass transfer mechanism in the sintering process of Y 2 O 3 ceramic has been investigated by Chen et al [12] . The diffusion of Y 3+ interstitials is considered as the controlling step of the grain boundary migration.…”