TY - JOUR
T1 - The influence of temperature on the solubility limit of Ca in alumina
AU - Ghosh, Priyadarshini
AU - Marder, Rachel
AU - Berner, Alex
AU - Kaplan, Wayne D.
N1 - Funding Information: This research was partially supported by the Israel Science Foundation (grant No. 1779/18 ). The authors acknowledge Paul Wynblatt for a critical review of the manuscript, Maytal Caspary Toroker, Li-or Cohen, and Michael Kalina for valuable discussions, and L. Rudnik for assistance with the quenching experiments. Publisher Copyright: © 2020 Elsevier Ltd
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Dopants and impurities can adsorb to surfaces and grain boundaries in ceramics, influencing the sintering kinetics and grain boundary mobility during processing. Ca is a common impurity in alumina that promotes grain growth at concentrations below the solubility limit, in contrast to the commonly observed solute-drag effect. Knowledge of the Ca solubility limit at temperatures relevant to processing is important to control microstructural evolution. Here we report on the experimentally measured solubility limit of Ca in α-alumina at 1400 °C and 1500 °C from equilibrated and quenched samples using standardized wavelength dispersive spectroscopy to be 32 ± 3 ppm and 45 ± 3 ppm, respectively. Together with the previously measured Ca solubility limit at 1600 °C, the enthalpy (0.95 eV per Ca) and vibrational entropy (-7.35 × 10−4 eV K-1 per Ca) of solution were determined. A negative vibrational entropy of solution indicates coulombic interactions between the Ca cations and charge compensating defects in α-alumina.
AB - Dopants and impurities can adsorb to surfaces and grain boundaries in ceramics, influencing the sintering kinetics and grain boundary mobility during processing. Ca is a common impurity in alumina that promotes grain growth at concentrations below the solubility limit, in contrast to the commonly observed solute-drag effect. Knowledge of the Ca solubility limit at temperatures relevant to processing is important to control microstructural evolution. Here we report on the experimentally measured solubility limit of Ca in α-alumina at 1400 °C and 1500 °C from equilibrated and quenched samples using standardized wavelength dispersive spectroscopy to be 32 ± 3 ppm and 45 ± 3 ppm, respectively. Together with the previously measured Ca solubility limit at 1600 °C, the enthalpy (0.95 eV per Ca) and vibrational entropy (-7.35 × 10−4 eV K-1 per Ca) of solution were determined. A negative vibrational entropy of solution indicates coulombic interactions between the Ca cations and charge compensating defects in α-alumina.
KW - Alumina
KW - Defect compensation
KW - Solid solution
KW - Solubility limit
KW - Wavelength dispersive spectroscopy
UR - https://www.mendeley.com/catalogue/72769472-31cb-35dc-8856-e8488ec4e6a6/
UR - http://www.scopus.com/inward/record.url?scp=85088639795&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.jeurceramsoc.2020.07.057
DO - https://doi.org/10.1016/j.jeurceramsoc.2020.07.057
M3 - Article
SN - 0955-2219
VL - 40
SP - 5767
EP - 5772
JO - Journal of the European Ceramic Society
JF - Journal of the European Ceramic Society
IS - 15
ER -