Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

This work describes a wet-processing route based on spray-freezing and subsequent lyophilization designed to obtain nanostructured ceramic/metal powders. Starting from the ceramic powder and the corresponding metal salt, a water-based suspension is sprayed on liquid nitrogen. The frozen powders are subsequently freeze-dried, calcined and reduced. The material was analyzed using X-ray diffraction analysis at all stages. High resolution transmission electron microscopy studies showed a uniform distribution of metal nanoparticles on the ceramic grain surfaces, good interfaces and high crystallinity, with an average metal particle size in the nanometric range.

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► A cryogenic route has been used to obtain ceramic/metal nanostructured powders.
► The powders present good homogeneity and dispersion of metal.
► The metal nanoparticle size distributions are centred in 17–35 nm.
► Both phases, ceramic and metal, present a high degree of crystallinity.
► Good metal/ceramic interfaces due to epitaxial growth, studied by HRTEM.