Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

Abstract

Ca 3 Co 4 O 9 is a p-type semiconducting material that is well-known for its thermoelectric (TE), magnetic, electronic, and electro-optic properties. In this study, sol-gel autoignition was used to prepare Ca 3 Co 4 O 9 at different calcination temperatures (773, 873, 973, and 1073 K) and time (4, 6, 8, 10, 12, and 14 h) using starch as a fuel. The phase and microstructure of the prepared Ca 3 Co 4 O 9 powder were investigated. Thermogravimetry-differential thermal analysis (TGA) confirms that the final weight loss occurred at 1073 K to form Ca 3 Co 4 O 9 stable powder. The variable-pressure scanning electron microscopy (VP-SEM) images show that the size of powder particles increases from 1.15 to 1.47 μm as calcination time increases from 4 to 12 h, and the size remains almost constant thereafter. A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction (XRD) analysis. The highest crystallinity is found about 92.9% when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460 Å crystallite size, respectively. Energy dispersive X-ray spectroscopy (EDS) analysis demonstrates that the calcinated powder has a high intensity of Ca, Co, and O with uniform distribution. High-resolution transmission electron microscopy (HRTEM) images prove that there is no distinct lattice distortion defect on the crystal structure.

Niobium Tungsten Oxides for Electrochromic Devices with Long-Term Stability

“…The Nb 18 W 16 O 93 film was prepared by a conventional sol–gel method (Figure S1 in the Supporting Information), which is a simple process, with mild reaction conditions and low requirements for equipment. − To determine the crystal structure and phase information, the high-resolution X-ray diffractometer (XRD) patterns of the Nb 18 W 16 O 93 film and bare fluorine-doped tin oxide (FTO) substrate are used, as shown in Figure a. In the XRD patterns of the Nb 18 W 16 O 93 film, two main peaks of the calcined Nb 18 W 16 O 93 thin films are observed, which are about 22.49° and 45.90°, respectively, corresponding to the diffraction of the orthorhombic phase (JCPDS 75-0561).…”

WITHDRAWN: Fabrication of Nimo Nanostructured Catalyst via Ultrasonic-Assisted Combustion Method Used in High Efficiency Thiophene Hydrodesulfurization: Influence of Organic Compound Type

“…The combustion technique is a fast, simple and energy saving method which is based on the redox reaction between an organic compound (fuel) and oxidizer agent, including sulfates, nitrates and carbonates [31,32]. A wide variety of organic compounds such as urea [33], glycine [34,35], citric acid [36], ethylene glycol [37], starch [38] and a mixture of them [39] have been used through combustion method.…”

Designing Breathing Air‐electrode and Enhancing the Oxygen Electrocatalysis by Thermoelectric Effect for Efficient Zn‐air Batteries

“…[Ca2CoO3] and hexagonal [CoO2] layers as reported in related references. [23] Both the layers of [Ca2CoO3] and [CoO2] have the same a, c and β lattice parameters but different b parameters. The atomic level HAADF-STEM image and the fitted results, as well as the lattice atomic arrangement model (Supplementary Fig.…”