Bi₂(C₂O₄)₃·7H₂O and Bi(C₂O₄)OH Oxalates Thermal Decomposition Revisited. Formation of Nanoparticles with a Lower Melting Point than Bulk Bismuth

Abstract

Two bismuth oxalates, namely, Bi(CO)·7HO and Bi(CO)OH, were studied in terms of synthesis, structural characterization, particle morphology, and thermal behavior under several atmospheres. The oxalate powders were produced by chemical precipitation from bismuth nitrate and oxalic acid solutions under controlled pH, then characterized by X-ray diffraction (XRD), temperature-dependent XRD, IR spectroscopy, scanning electron microscopy, and thermogravimetric differential thermal analyses. New results on the thermal decomposition of bismuth oxalates under inert or reducing atmospheres are provided. On heating in nitrogen, both studied compounds decompose into small bismuth particles. Thermal properties of the metallic products were investigated. The Bi(CO)OH decomposition leads to a Bi-BiO metal-oxide composite product in which bismuth is confined in a nanometric size, due to surface oxidation. The melting point of such bismuth particles is strongly related to their crystallite size. The nanometric bismuth melting has thus been evidenced ∼40 °C lower than for bulk bismuth. These results should contribute to the development of the oxalate precursor route for low-temperature soldering applications.

The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide

“…Futhermore, both samples also showed the vibrational band at 1384 cm -1 indicating the vibration of Bi-O stretching [16]. Meanwhile, there was a vibrational band which was not very intense at the wavenumber about 2164 cm -1 indicating the absorption area for Bi-O-H stretching [17]. Furthermore, evidence indicating that H 2 C 2 O 3 and NaCO 3 have been completely removed can be seen in the disappearance of IR peaks at 1700 cm -1 and 1100 cm -1 wavenumbers atributed to C=O and C-O functional groups, respectively.…”

Two molybdenyl carbonates with different dimensional structures exhibiting huge differences in band gaps

“…The IR spectra of Cs The assignments are in agreement with the previous reports. [35][36][37][38] The UV-vis diffuse reflectance data were obtained for Cs 2 MoO 3 (CO 3 ) and Cs 3 MoO 4 (HCO 3 ) (Fig. 4), and the absorption data were obtained using the Kubelka-Munk function.…”

Crystal Structure and Thermal Behavior of SbC2O4OH and SbC2O4OD

“…Some examples are Cd 2 C 2 O 4 (OH) 2 [1], ZrC 2 O 4 (OH) 2 [2], BiC 2 O 4 OH [3] and the title compound. Due to their moderate thermal stability, they have been used as precursors in materials synthesis, for instance for the fabrication of metal/metal oxide composites [4]. Antimony oxalate hydroxide, SbC 2 O 4 OH, was reported to form by refluxing freshly prepared antimony(III) oxide in oxalic acid and was found as a colorless precipitate when oxalic acid was added to a solution of SbCl 3 in hydrochloric acid [5].…”