Nanocomposites and nanomaterials

Transformation of free volumes in the Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics caused by interphase mass-transfer processes
H. Klym1, A. Ingram2, I. Hadzaman3, O. Shpotyuk4, Yu. Kostiv1

1 Lviv Polytechnic National University, Bandery str., 12, Lviv-79013, Ukraine 
E-mail: halyna..klym@lpnu.ua; klymha@yahoo.com  
2 Opole University of Technology, Ozimska str., 75, Opole- 45370, Poland
3Drohobych Ivan Franko State Pedagogical University, Ivan Franko str., 24, Drohobych-82100, Ukraine
4 Vlokh Institute of Physical Optics, Dragomanova str., 23, Lviv-79005, Ukraine

Technologically-modified Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics are widely used as one of the most perspective materials for application as negative temperature coefficient thermistors, precise temperature sensors, in-rush current limiters, etc. Typically, structural properties of such materials re studied using different traditional method of structural characterizations. Our previous investigations have shown that the quantity of the additional phase and its distribution in bulk and on the surface of ceramics are influenced by temperature-time sintering regimes [1]. 
Also we used positron annihilation lifetime spectroscopy to study of free volumes in temperature-sensitive spinel ceramics [1]. It is established that the amount of additional NiO phase in these ceramics extracted during sintering play a decisive role. The process of monolitization from the position of evolution of grain-pore structure was studied in these ceramics using positron annihilation lifetime spectroscopy within two-component fitting procedures. In addition, NiO phase results in transformation of free-volume places in the inner structure of ceramics. To study free volumes formed by NiO and nanopores in Cu0.1Ni0.8Co0.2Mn1.9O4 ceramics three-component fitting procedures and using positron-positronium trapping algorithm was used this work.
   
1.	Klym H., Ingram A., et. al. Structural studies of spinel manganite ceramics with positron annihilation lifetime spectroscopy // Journal of Physics: Conference Series, 2011, 289(1), pp.012010.
2.	Klym H., et al. Degradation transformation in spinel-type functional thick-film ceramic materials // Microelectronics Reliability, 2014, 54(12), pp. 2843-2848.