Stretched-to-compressed-exponential crossover observed in the electrical degradation kinetics of some spinel-metallic screen-printed structures

• Published in: Chemical physics Vol. 501; pp. 121 - 127
• Main Authors: Balitska, V., Shpotyuk, O., Brunner, M., Hadzaman, I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 14.02.2018
• Subjects: Ceramics; Compressed-exponential; Electrical relaxation; Kinetics; Spinel; Stretched-exponential; Electrical relaxation; Stretched-exponential; Ceramics; Kinetics; Spinel; Compressed-exponential
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2017.12.020

Thermally-induced (170 °C) degradation-relaxation kinetics is examined in screen-printed structures composed of spinel Cu0.1Ni0.1Co1.6Mn1.2O4ceramics with conductive Ag or Ag-Pd layered electrodes. Structural inhomogeneities due to Ag and Ag-Pd diffusants in spinel phase environment play a decisive role in non-exponential kinetics of negative relative resistance drift. If Ag migration in spinel is inhibited by Pd addition due to Ag-Pd alloy, the kinetics attains stretched exponential behavior with ∼0.58 exponent, typical for one-stage diffusion in structurally-dispersive media. Under deep Ag penetration into spinel ceramics, as for thick films with Ag-layered electrodes, the degradation kinetics drastically changes, attaining features of two-step diffusing process governed by compressed-exponential dependence with power index of ∼1.68. Crossover from stretched- to compressed-exponential kinetics in spinel-metallic structures is mapped on free energy landscape of non-barrier multi-well system under strong perturbation from equilibrium, showing transition with a character downhill scenario resulting in faster than exponential decaying.