Nanocomposites and nanomaterials

Peculiarities of preparing and characterization of thick-film nanostructures based on ceramics for sensors applications
H. Klym1, I. Hadzaman2, Vasylchyshyn I.1

1 Lviv Polytechnic National University, Bandery str., 12, Lviv-79013, Ukraine 
E-mail: halyna..klym@lpnu.ua; klymha@yahoo.com 
2 Ivan Franko Drohobych State Pedagogical University,
I. Franko str., 24, Drohobych-82100, Ukraine
Thick-film performance of ceramics based on the mixed NiMn2O4-CuMn2O4-MnCo2O4 system has a number of advantages over other types of functional electroceramics, especially in combination with layers of humidity-sensitive nanostructured MgО-Al2O3 ceramics. The aim of this work is fabrication and characterization of structural properties of temperature- and humidity-sensitive thick-film nanostructures.
Thick-film temperature-sensitive elements and multilayered structures based on Cu0,1Ni0,8Co0,2Mn1,9O4 with p-type electrical conductivity, Cu0,1Ni0,1Co1,6Mn1,2O4 with р+- type of electrical conductivity and dielectric MgО-Al2O3 (i-type) were investigated. The humidity-sensitive thick-film layer was applied to pre-formed temperature-sensitive layer. It should be noted that formation of p-р+, p-р+р, thick-film structures and integrated temperature-humidity-sensitive p-і-р+ structures was carried out within one technological cycle.
It is shown structure of humidity-sensitive thick films is especially expressly selected on a background of Al2O3 substrate with conductive Ag layer. Evidently, that material contains the far of shallow pores, which serve as ducting for the receipt of water to nanopores, where processes of capillary condensation takes place, and also macropores which provide the effective receipt of water in the inner structure of material from an environment.
In contrast to microstructure of humidity-sensitive MgО-Al2O3 thick films, Cu0,1Ni0,8Co0,2Mn1,9O4 thick films contain a greater amount of macropores formed in clusters. A similar structure is also characteristic for bulk material of the same composition. Thus, the structural features of ceramics can be transformed into thick films of similar compositions.The use of ceramic with a spinel structure as the main output component for preparation of thick films provided the density of the multi-layer structure and the component for the production of thick films, provided the density of the multi-level structure and contact of their layers.