Grain boundary energy control in zinc aluminate nanoceramics

LS Martin and A Campos-Quiros and M Watanabe and JK Mason and PCM Fossati and BP Uberuaga and RHR Castro, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 108 (2025).

DOI: 10.1111/jace.20383

This study investigates the grain boundary energy dependence on segregated dopants in nanocrystalline zinc aluminate ceramics. Atomistic simulations of Sigma 3 and Sigma 9 grain boundaries showed that trivalent ions of varying ionic radii Sc3+ (74.5 pm), In3+ (80.0 pm), Y3+ (90.0 pm), and Nd3+ (98.3 pm) have a tendency to segregate to both interfaces, with Y3+ presenting the highest segregation potentials. The connection between segregation and the reduction of interfacial energies was explored by measuring the grain boundary energy on nanoceramics fabricated via high-pressure spark plasma sintering (HP-SPS) using differential scanning calorimetry (DSC). The results revealed that Y3+ doping at 0.5 mol% reduces the grain boundary energy in zinc aluminate nanoceramics from 1.1-1.3 J/m2 to 0.6-0.8 J/m2; the range correlates with the observed size dependence of the excess energy, with higher values observed for the smaller grain sizes (similar to 17 nm). The noted decrease in interfacial energies for doped samples suggests it is indeed possible to alter the stability of zinc aluminate grain boundaries via dopant segregation.

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