Thermodynamics and kinetics of sintering of Y₂O₃

Abstract

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Thermodynamic and kinetic analyses of sintering in Al‐doped Y2O3 nanoparticles

“…Figure 5 plots the grain sizes of the undoped and Al‐doped samples calcined up to varying temperatures. The grain sizes were measured from the SEM images (Figure 6) showing similar morphology to the equivalent undoped samples as reported in our previous work 1 . Figure 5 shows that the grain sizes of the Al‐doped samples are consistently smaller than their undoped counterparts up to 1150℃, which is likely the result of increased nanostability as discussed earlier 9,36 .…”

“…The intensity of the peaks was equivalent to that for undoped Y 2 O 3 , suggesting that particles are similarly isotropic, as later confirmed with microscopy. The calculated crystallite size was 10.2 ± 0.2 nm (with BET surface area of 82.2 ± 0.1 m 2 /g), which was smaller than the undoped Y 2 O 3 nanoparticles (13.7 ± 0.1 nm, 58.2 ± 0.3 m 2 /g) synthesized using the same method and calcined at the same condition 1 . It is interesting to note that not only the crystallite size was reduced with doping but also the surface area was increased.…”

“…Peak 2 for the Al‐doped sample showed higher intensity than Peak 1, which is the opposite trend observed in the undoped Y 2 O 3 . It was previously proposed that Peak 1 from the deconvolution of DSC peak in Y 2 O 3 can be attributed to densification, followed by Peak 2 as a grain growth peak 1 …”

“…A, Differential scanning calorimeter sintering curve of undoped Y 2 O 3 obtained at 40 K/min heating rate (replotted from a figure in Ref. [1]) and (B) of Al‐doped Y 2 O 3 at 15 K/min heating rate for samples coarsened at 750℃ for 15 h after baseline subtraction and deconvolution…”

“…Even though surface and grain boundary energies of solid materials are small (~ a few J/m 2 ), the developments in synthesis of nanoparticles with large interfacial areas, as well as microcalorimetry and microstructure analysis techniques, have enabled this direct quantification of such small thermodynamic parameters. Apparent activation energy of sintering was also measured using a DSC following the Kissinger method as detailed in our previous work 1,28 …”