Nanocomposites and nanomaterials

Combined study of spinel-based thick-film nanostructures
H. Klym1, I. Hadzaman2, A. Ingram3, I. Vasylchyshyn1

1Lviv Polytechnic National University, Bandery str., 12, Lviv-79013, Ukraine 
E-mail: halyna.i.klym@lpnu.ua; klymha@yahoo.com 
2Drohobych Ivan Franko State Pedagogical University, Ivan Franko str., 24, Drohobych-82100, Ukraine
3Opole University of Technology, Ozimska str., 75, Opole- 45370, Poland
In this work temperature-sensitive thick-film elements based on spinel-type NiMn2O4-CuMn2O4-MnCo2O4 manganites with p+/p-type of electrical conductivity and their p+-p structures were prepared (using ecological glass constituents without Pb additives) and investigated. These elements possess good electrophysical characteristics before and after long-term ageing test at 170 оС [1]. The degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p- and p+- conductive thick films. The p+-p structures were of high stability, the relative electrical drift being no more than 1 %. 
In respect to scanning electron microscopy data thick films show higher density and microstructure homogeneity with uniform distribution of grains, glass additives and pores. During sintering process of thick-film structures the diffusion of elements occurs from one layer into near-surface region of the next layer with other conductivity. 
Experimental positron annihilation lifetime spectra, measured for the Cu0.1Ni0.1Co1.6Mn1.2O4 (Co-enriched) bulk ceramics and multilayered thick films, are decomposed into two discrete components (1, I1) and (2, I2), showing no positronium formation. The observed components can be fully defined within the two-state positron trapping model. The positrons are trapped more strongly in thick films due to glass additives near grain boundaries in these materials and void agglomeration during technological process.
Thus, p+/p-conductive thick films and their p+-p structures based on spinel-type NiMn2O4-CuMn2O4-MnCo2O4 manganites are stable and after technological optimization with PAL method can be used as active elements for miniature temperature sensors. 

1.	Klym H., Hadzaman I., Ingram A., Shpotyuk O. Multilayer thick-film structures based on spinel ceramics // Canadian Journal of Physics, 2014, 92(7/8), 822-826.