Special Issue "Rare Earth Oxides and Their Applications"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Energy Materials".

Deadline for manuscript submissions: 31 August 2020.

Special Issue Editor

Prof. Ginesa Blanco
Website
Guest Editor
Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real (Cádiz), Spain
Interests: rare earth oxides; catalysts characterization; nanostructured catalysts; CO2 reduction; surface snalysis; XPS

Special Issue Information

Dear Colleagues,

Rare earth elements, according to the IUPAC recommendations, comprise a group of 17 elements, Sc, Y and the lanthanoids (from La to Lu). In principle, the term “rare” suggests that they are rather scarce elements, although they are actually more abundant in the Earth’s crust that some much better known elements. Thus, their abundance varies from 66 ppm in the case of Ce (an abundance similar to that of Cu or Zn) to less than 0.5 ppm in Tm (more abundant that Cd or Se). The term “rare” seems to be applied in the sense of “strange” or “extraordinary”, rather than “scarce”. For these reasons, it is not surprising the huge number of applications that all these elements have, both in bulk production industry or in minor volume applications. It has to be taken into account, as well, that most of the rare earth-containing materials with industrial applications are either oxides, or they are obtained from oxides. Regarding the bulk and mature industry applications of rare earth oxides, their use in catalysts formulations (such as in three way automotive catalysis), in glass-related industries (glass making, decolouring or colouring, glass polishing and other related applications), and permanent magnets manufacturing account for almost 70% of rare earth oxides usage. Other important industrial applications concern the metallurgy industry (used as additives in Fe or Al metal alloys), ceramics (specially in the case of Y), lighting-related applications (in the form of phosphors), as battery alloy components, or in solid oxide fuel cells, amongst others. Additionally, but not less important, there are lower scale applications, such as biomedical uses of nanoparticulated systems containing rare earth oxides for cancer treatment or as tumoral detection markers, or as sunscreens cosmetics for skin protection.

The aim of this Special Issue is to cover many of the above-mentioned applications, with a special focus on new developments for existing applications as well as the emergence of new and innovative ones. It is my pleasure to invite you to submit a manuscript to this Special Issue. Full papers, communications, and reviews will be welcome.

Prof. Ginesa Blanco
Guest Editor

Manuscript Submission Information

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Keywords

  • Rare earth oxides
  • Lanthanoids
  • Applications

Published Papers (3 papers)

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Research

Open AccessArticle
Photocatalytic Degradation of Diclofenac Using Al2O3-Nd2O3 Binary Oxides Prepared by the Sol-Gel Method
Materials 2020, 13(6), 1345; https://doi.org/10.3390/ma13061345 - 16 Mar 2020
Abstract
This paper reports the sol-gel synthesis of Al2O3-Nd2O3 (Al-Nd-x; x = 5%, 10%, 15% and 25% of Nd2O3) binary oxides and the photodegradation of diclofenac activated by UV light. Al-Nd-based [...] Read more.
This paper reports the sol-gel synthesis of Al2O3-Nd2O3 (Al-Nd-x; x = 5%, 10%, 15% and 25% of Nd2O3) binary oxides and the photodegradation of diclofenac activated by UV light. Al-Nd-based catalysts were analyzed by N2 physisorption, XRD, TEM, SEM, UV-Vis and PL spectroscopies. The inclusion of Nd2O3 in the aluminum oxide matrix in the 10–25% range reduced the band gap energies from 3.35 eV for the γ-Al2O3 to values as low as 3.13–3.20 eV, which are typical of semiconductor materials absorbing in the UV region. γ-Al2O3 and Al-Nd-x binary oxides reached more than 92.0% of photoconverted diclofenac after 40 min of reaction. However, the photocatalytic activity in the diclofenac degradation using Al-Nd-x with Nd2O3 contents in the range 10–25% was improved with respect to that of γ-Al2O3 at short reaction times. The diclofenac photoconversion using γ-Al2O3 was 63.0% at 10 min of UV light exposure, whereas Al-Nd-15 binary oxide reached 82.0% at this reaction time. The rate constants determined from the kinetic experiments revealed that the highest activities in the aqueous medium were reached with the catalysts with 15% and 25% of Nd2O3, and these compounds presented the lowest band gap energies. The experimental results also demonstrated that Nd2O3 acts as a separator of charges favoring the decrease in the recombination rate of electron-hole pairs. Full article
(This article belongs to the Special Issue Rare Earth Oxides and Their Applications)
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Open AccessArticle
Liquid Regions of Lanthanum-Bearing Aluminosilicates
Materials 2020, 13(2), 450; https://doi.org/10.3390/ma13020450 - 17 Jan 2020
Abstract
The Al2O3-SiO2, La2O3-Al2O3, and La2O3-SiO2 binary phase diagrams were estimated by Redlich–Kister expression. La4.67Si3O13 (=La4.67(SiO4) [...] Read more.
The Al2O3-SiO2, La2O3-Al2O3, and La2O3-SiO2 binary phase diagrams were estimated by Redlich–Kister expression. La4.67Si3O13 (=La4.67(SiO4)3O) was introduced to improve the existing phase diagrams. The Al2O3-SiO2-La2O3 ternary phase diagram extrapolated by Kohler method was optimized. Then, the liquidus of Al2O3-SiO2-La2O3 system at 1600 °C was compared with Al2O3-SiO2-RE2O3 (RE = Rare Earth Elements) systems and experimental results in other literature. The high temperature experiments were conducted in the tube furnace at 1500 °C. Then the field emission scanning electron microscope (FE-SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) were employed to verify the calculated liquid region and precipitates phase at 1500 °C. Moreover, the liquidus of binary systems were compared with FactSage results and experiments. The optimized ternary phase diagram shows the relatively reliable region of liquid phase, and it is significant to the seal glass of solid oxide fuel cells and other fields being related to RE containing silicates. Full article
(This article belongs to the Special Issue Rare Earth Oxides and Their Applications)
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Open AccessFeature PaperArticle
Improved NOx Storage/Release Properties of Ceria-Based Lean NOx Trap Compositions with MnOx Modification
Materials 2019, 12(13), 2127; https://doi.org/10.3390/ma12132127 - 02 Jul 2019
Cited by 1
Abstract
Ceria/spinel-based lean NOx trap compositions with and without barium were modified with MnOx via incipient wetness impregnation. The effect of the MnOx layer on the aged materials (850 °C) as to the NOx storage and release properties was investigated [...] Read more.
Ceria/spinel-based lean NOx trap compositions with and without barium were modified with MnOx via incipient wetness impregnation. The effect of the MnOx layer on the aged materials (850 °C) as to the NOx storage and release properties was investigated via NOx adsorption (500 ppm NO/5% O2/balance N2) carried out at 300 °C in a dual-bed with a 1% Pt/Al2O3 catalyst placed upstream of the samples to generate sufficient amounts of NO2 required for efficient NOx storage. Subsequent temperature programmed desorption (TPD) experiments were carried out under N2 from 300 °C to 700 °C. The addition of MnOx to the barium free composition led to a slightly reduced NOx storage capacity but all of the ad-NOx species were released from this material at significantly lower temperatures (ΔT ≈ 100 °C). The formation of a MnOx layer between ceria/spinel and barium had a remarkable effect on ageing stability as the formation of BaAl2O4 was suppressed in favour of BaMnO3. The presence of this phase resulted in an increased NOx storage capacity and lower desorption temperatures. Furthermore, NOx adsorption experiments carried out in absence of the Pt-catalyst also revealed an unexpected high NOx storage ability at low NO2/NO ratios, which could make this composition suitable for various lean NOx trap catalysts (LNT) related applications. Full article
(This article belongs to the Special Issue Rare Earth Oxides and Their Applications)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. NMxCe1-xO2 (NM = noble metal) nanoparticles deposited on a high surface supports – a hierarchical catalyst of exceptional stability

Karolina A. Ledwa and Leszek Kępiński*

Polish Academy of Sciences, Institute of Low Temperature and Structure Research, Okolna 2, 50-422 Wrocław, Poland

 

 2. Oxygen storage capacity and Oxygen mobility of Rh-low-loading RE oxides

Thomas Belin1, Nicolas Bion, Fabien Can, Daniel Duprez, Carlos V. M. Inocencio, Anthony Le Valant,  Alice Mouchet, Cédric Bara, Sébastien Jus, Diego Lopez Gonzalez

1) Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers, CNRS, 4 rue Michel Brunet TSA51106, 86073 Poitiers Cedex 9, France;

2) Solvay - Centre de Recherche et Innovation de Paris, 40 rue de la Haie Coq , 93308 Aubervilliers, France

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