In the present study the thermal decomposition of a freeze-dried copper(II) acetate monohydrate powder, (CH 3 COO) 2 Cu . H 2 O, (FDCuAcH 2 O), was analysed by a combination of high-temperature X-ray diffractometry; differential scanning calorimetry and thermogravimetry, up to 700 °C. The structure and morphology of the calcined freeze-dried powders were analysed by scanning electron microscopy and X-ray diffractometry. The results showed that FDAcCuH 2 O decomposes during heating in two stages: I) (25-225 °C) FDCuAcH 2 O dehydrates giving rise to copper(II) acetate, (CH 3 COO) 2 Cu, (AcCu), and II) (225-525 °C) AcCu decomposes to CuO through complex oxidation reactions of Cu and Cu 2 O, simultaneously. SEM showed that FDCuAcH 2 O powder has a scale-like morphology, which is created in the freezing stage and retained after freeze-drying. After calcination at 125 and 225 °C, clusters of elongated tubes (or filaments) compose the resulting powder (AcCu). Subsequent calcination at temperatures above 325 °C resulted in hard clusters of spheroid-like CuO particles.
Zinc oxide (ZnO)‐based varistors are metal oxide varistors whose nonlinear properties are characterized by electrical resistance that decreases as the applied field increases. The multiphasic nature of varistors leads to the formation of Schottky barriers, which are responsible for the materials' nonlinear behavior. The objective of this work was to image the potential barriers in ZnO doped with 0.5 mol% Cu and x wt% G (G is a frit and x=0, 1, and 5 wt%). The frit served to form a glassy insulating layer around the grain boundaries. Samples were sintered at 1050°C and the microstructures were analyzed using a Nanoscope IIIa atomic force microscope. The results of the electric force microscopy experiments map the electric field distribution on the surface of CuO–ZnO‐based ceramics.
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