International Materials Reviews

The recognition that bulk nanoceramic materials, having grain sizes typically 100 nm or finer, possess appealing mechanical, physical and tribological properties has generated considerable recent research activity. A major challenge in the research on bulk nanoceramics and nanoceramic composites is concerned with the aspect of processing, in particular restriction of grain growth during sintering. In this regard novel processing techniques have been developed with the aim of fabricating bulk ceramic nanomaterials. The superior properties exhibited by these bulk nanoceramics and ceramic nanocomposites, compared with conventional ceramic materials, have opened up prospects for their use in applications demanding better mechanical properties. The present review highlights outstanding issues related with the processing of nanoceramics and ceramic nanocomposites, discusses the novel processing techniques currently used to develop these materials, critically analyses the property modifications resulting from microstructural refinement and provides an overview of the structure–property correlations of some recently developed bulk nanoceramic materials. Potential fields of application for ceramic nanomaterials are surveyed. In conclusion, the unresolved issues related to bulk nanoceramic processing are considered and a perspective is given of areas of future research.

In recent years, a significant interest has developed on metallic nanostructures based sensors for the detection of gas, volatile organic compounds (VOCs), and biomolecules in the wake of counter-terrorism threats and environmental pollution. Enhancement in selectivity and overall efficiency of the sensors is achieved by tailoring size, structure and shape of the nanoparticles. In the last decade, numerous studies revealed various sensing properties of these nanomaterials. However, improvements in overall sensor performance such as sensitivity, selectivity, response time, recovery time and robustness demand further improvement. This warrants a proper understanding of the basic principles behind the sensing properties of metallic nanostructures. In this review, principles of few important sensing systems, their sensing mechanisms, merits and demerits along with some of the applications on the detection of gas, VOC and biological molecules are discussed. This review also highlights the importance of using metal nanostructures in various sensor systems. Although the development of nanotechnology provides new avenue to sensor research, there exist several unexplored territories for the application of nanostructured materials onto the device. This review encompasses some significant efforts on the application of nanomaterials in the various sensing systems.