Abstract
In this work, nanoparticles of cerium hydroxycarbonates were synthesized by a facile hydrothermal treatment at 120°C with ammonium carbonate as the precipitating/mineralizer agent in diluted solution. The as-formed amorphous coprecipitate undergoes several morphological and structural modifications as a function of the duration of the hydrothermal treatment, leading after 8 h to the formation of monosized nanoparticles of hexagonal CeCO3OH. A similar behavior has been found when neodymium-based precursors are used as well, whereas the same treatment produces very different results by using different lanthanides-based precursors in terms of formed phases and morphologies, thus leading to the formation of pure tengerite-type structure phases, biphasic systems (tengerite type and hexagonal), or even entirely amorphous systems. Furthermore, the hydrothermal transformation is influenced by the redox behavior of the rare-earth cation (i.e., cerium) too, eventually resulting in the formation of fluorite-like structures. Therefore, a specific pathway of Ce(III) precursor transformations during hydrothermal treatment is proposed in this paper. Definitely, our results show that ammonium carbonate can be used as the precipitating/mineralizer agent to obtain cerium, doped-cerium, and neodymium hydroxycarbonates, which show excellent morphologies (i.e., characterized by spherical, nanosized particles with monomodal size distribution). Therefore, they can be used as optimal precursors for oxide powders. Conversely, when tengerite-type carbonate precursors are formed, their morphology is characterized by large and acicular particles.
Highlights
Rare-earth-based materials have drawn attention in the past years due to their wide range of applications, in the lighting industry [1], in electrochemical energy devices [2], in catalysis [3], and in biological [4] and magnetic [5] applications. eir very interesting properties are largely due to the unique 4f electron orbitals having highly localized electronic states and very predictable electronic transitions [6], weakly influenced by either the coordination environment or the crystal field
Our results show that ammonium carbonate can be used as the precipitating/ mineralizer agent to obtain cerium, doped-cerium, and neodymium hydroxycarbonates, which show excellent morphologies. erefore, they can be used as optimal precursors for oxide powders
(c) e as-prepared suspensions were transferred in Teflon vessels (60 mL), which were sealed and held in outer stainless steel pressure vessels for the hydrothermal treatment. e treatment was carried out in an air-thermostated rotating oven at 120°C and 25 rpm to allow the complete homogenization of the system during the process
Summary
Rare-earth-based materials have drawn attention in the past years due to their wide range of applications, in the lighting industry [1], in electrochemical energy devices [2], in catalysis [3], and in biological [4] and magnetic [5] applications. eir very interesting properties are largely due to the unique 4f electron orbitals having highly localized electronic states and very predictable electronic transitions [6], weakly influenced by either the coordination environment or the crystal field. Various synthesis methods have been proposed to produce different rare-earth carbonates, and among them, the most common ones are precipitation [11] and homogeneous precipitation [12, 13], sonochemical synthesis [14], and hydrothermal treatment [15, 16]. The latter can be considered an effective and cheap route, thanks to low synthesis temperature, high powder reactivity, and shape control [17, 18], and it can be frequently used for large-scale production [8]. Some recipes for preparing rareearth carbonate-based powders via facile hydrothermal synthesis are proposed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
