Structure-property correlations for the surfactant-free faceted nanocrystals of Ce1−xZrxO2 and their bulk ceramics

Faceted nanocrystals involving Ce_1−xZr_xO₂ (CZ) system bound by (101) and (l10) facets were synthesized via co-precipitation route. The novelty of this process relies on the fact that the synthesis did not involve any surfactant/ligand for morphology control (for all the CZ compositions) and the nanocrystals retained their shapes at high temperatures (> 800 °C). Catalytic and photocatalytic degradation properties were suitably examined for the CZ nanocrystals; substantial (∼90%) degradation of the methylene blue dye was observed only in 60 min of visible light irradiation. Ce_1−xZr_xO₂ ceramics with near-theoretical density (>98%) obtained at 1580 °C (for 2 h) confirmed excellent sinterability for the synthesized CZ nanocrystalline powders. The ionic conductivities of the doped-ceria ceramics increased with temperature and frequency. A maximum conductivity of ∼2 × 10⁻³ S/cm was measured at 600 °C at 1 MHz for Ce_0.4Zr_0.6O₂ ceramic; previous works obtained similar data at 900 °C or beyond for the same composition.