Intelligent Ceramic Materials for Chemical Sensors

Recently, the search for novel functions has received increasing attention in the field of materials. The development of materials with intelligent functions is a key point for the development of novel technologies. One class of materials which has outstanding possibilities for application as intelligent materials is electroceramics, and one of the most appealing uses of functional ceramics is in the chemical sensor field. The materials conventionally used in this field show many problems, such as insufficient gas selectivity, inability to detect very low gas concentrations, and changes in sensing properties caused by surface contamination. In order to overcome these problems, one possible solution is the design of materials with novel detection mechanisms. In this paper, examples of intelligent ceramic materials for humidity and gas sensors are reported, i.e., multifunctional La ₂ CuO ₄ /ZnO p-n heterocontacts, Au/ZnO Schottky barriers, and sol-gel processed thin films of TiO ₂ with 10 at% of K. The intelligent materials functions of these systems are based on the multiphase interaction of materials having different properties, such as p-type/n-type semiconductors, metal/ceramic and conductor/insulator.