Thermal decomposition of basic cobalt and copper carbonates

Abstract

Basic cobalt and copper carbonates were prepared by precipitation from solutions of their nitrates using KHCO3 at room temperature in CO2 atmosphere. The thermal decomposition of the prepared basic carbonates was studied by means of TG and DTA techniques and the phases produeed were identified by XRD measurements. The products obtained at 400~ were subjected to different doses of gamma-rays (40-160 M rad) and the thermal stabilities of these solids were investigated.The results obtained revealed that basic cobalt carbonate decomposed at 335~ to produce Co~O4 which remained stable up to 850 ~ and then decomposed above this temperature giving CoO which transformed into Co304 on cooling to room temperature. Basic copper carbonate dissociated at 290~ yielding CuO which yielded Cu20 and metaUie copper at 1060 and 1150~ respectively. However, the produced cuprous oxide and metallic copper solids were converted into CuO and Cu20, respectively by cooling in air to room temperature.Gamma-irradiation decreased the thermal stability of Co304 to an extent proportional to the dose employed. On the other hand, this treatment increased the thermal stability of both CuO and Cu20.

Synthesis, characterization and thermal behaviour on solid pyruvates of some bivalent metal ions

“…The mass loss observed between 900 and 930 °C, is ascribed to the reduction of Co 3 O 4 to CoO (Calcd. = 1.81%; TG = 1.74%) in agreement with the literature [17,18].…”

Synthesis and characterizations of (Mg, Co, Ni, Cu, Zn)O high-entropy oxides

“…The earlier works from the literature suggest that the mixing enthalpies (ΔH mix ) of the ZnO Wurtzite and CuO tenorite to their corresponding rock-salt crystal structure transformation are about 25 kJ/ mol and 22 kJ/mol, respectively [47]. The positive ΔH mix indicates incomplete miscibility which leads to phase segregation at lower temperatures and can be stabilized at higher temperatures [48,49] and this could be the main reason for detecting the tenorite and Wurtzite phases at lower temperatures.…”

Optical, electrical and microstructural studies of monoclinic CuO nanostructures synthesized by a sol–gel route

“…Hence, the decomposition of the carbonate to the oxide and CO 2 would have taken place at a higher temperature such as 290 1C during the initial heating process. 15 Thereafter the prepared CuO nanostructures are collected as a black color powder. An X-ray diffractometer system [X'PERT PRO PANalytical, Netherlands] with CuKa radiation (l = 0.1540) nm was used to identify the crystal structure of the particles.…”