Basic Introduction

Erbium oxide, also known as Er?O?, is a rare earth oxide that has garnered significant attention due to its unique properties and diverse applications. This pinkish powder is slightly soluble in inorganic acids, and completely insoluble in water. When heated to 1300°C, erbium oxide transforms into hexagonal crystals and does not melt.[1]

Synthesis and Production

General procedure: For the synthesis of the ErxZn1-xO NPs, zinc nitrate hexahydrate(Zn(NO3)2·6H2O), erbium nitrate pentahydrate (Er(NO3)3·5H2O),ethylene glycol (C2H4(OH)2) and citric acid (C6H8O7) were used. All reagents were of analytical grade (purchased from Sigma-Aldrich) and were used without further purification. For this synthesis, the precursor (resin) was produced according to the following steps. Firstly, citric acid (47.7 % w/w) and zinc nitrate hexahydrate (31.7 %w/w) were dissolved in ethylene glycol (20.6 % w/w) at ～70 °C under magnetic stirring. Second, to promote polymerization betweenC6H8O7 and C2H4(OH)2, the temperature was raised to ～120 °C. Next, for the formation of the x = 0.000 NP sample (ZnO), the produced resin was annealed for 12 h at 500 °C in a resistive furnace. Then, for the production of the doped samples (x > 0.000), stoichiometric amounts of erbium nitrate pentahydrate were diluted in deionized water and added to the as-produced resin, under magnetic stirring; the resulting solution was then annealed at 500 °C for 12 h, leading to the ErxZn1-xO NPs with different Er-content (x). In this synthetic route, the amount of resin and ZnO NPs produced were weighted to obtain the precursor yield: mass of ZnO produced/mass of resin. For production of the erbium oxide reference sample (Er2O3-RS), the same process described above was carried out to produce a precursor containing erbium, using ethylene glycol, citric acid, and erbium nitrate pentahydrate instead zinc nitrate hexahydrate. The resulting resin was also annealed at 500 °C for 12 h to produce theEr2O3-RS nanopowder.

Application

Optical Materials and Devices

The application of erbium in optical materials is mainly based on its absorption and emission properties of light.[2] The optical materials have experienced significant enhancements owing to the incorporation of rare earth elements. The incorporation of rare earth elements into glasses and ceramics has garnered significant attention in recent years since it enhances optical, electrical, and structural capabilities, notably in third-order non-linear optics, crucial for modern applications like optical switching and signal processing. Their diverse properties, deriving from the unique electronic configurations of the rare earth ions, offer many possibilities for both existing and emerging photonic technologies. For instance, the absorption and emission properties of rare earth ions can be exploited to design laser and amplifier optical materials among others. Er3+-doped fiber amplifiers (EDFAs), e.g., had played an important part in revolutionizing the telecommunications industry by allowing long-distance signal transmission without significant loss. They also enable signal amplification without the need for conversion of the optical signal into an electrical one.When erbium ions are tragically mixed into glass, crystals and other matrix materials, the optical properties of the materials will be changed. For example, in glass materials, the energy level transitions of erbium ions lead to absorption and emission of light at specific wavelengths, which results in the glass taking on a specific color (e.g. erbium oxide doped glass is rose-red). At the same time, erbium doping can also affect the refractive index, fluorescence lifetime and other optical parameters of the material, and these properties can be used to prepare a variety of optical devices. In the manufacturing process of optical glass, erbium-doped glass can be used to manufacture filters, optical lenses and so on. Filters can selectively transmit or block specific wavelengths of light, and are used in optical instruments, photographic equipment, optical communications and other fields. Filters can selectively transmit or block specific wavelengths of light, and are widely used in optical instruments, photographic equipment, optical communications and other fields. In display technology, erbium-doped fluorescent materials can be used to manufacture phosphors for color displays. By doping with other rare earth elements, a richer and more vivid color display effect can be achieved. In the field of optical sensors, erbium ions are sensitive to certain substances or physical quantities (such as temperature, pressure, magnetic field, etc.), corresponding optical sensors can be prepared to achieve the measurement of these parameters by detecting the change of optical signals, which has potential application prospects in environmental monitoring, industrial automation control and other aspects. It has potential application prospects in environmental monitoring, industrial automation control.

Catalyst

Noble metal nanoparticles (NPs) have become one of the hottest topics in the past decades due to their ultra-small size and unique optical and electrical properties. [3]Although some base metals such as Fe, Co, and Ni possess catalytic activity for hydrogenation reactions, they face the problem of irreversible deactivation under liquid-phase conditions and tend to lack the predictability, efficiency, and generality necessary for wide spread use. Many reports have manifested that noble metal nanoparticles anchored on oxide supports can exhibit effective catalyst activity in nanoscience and catalysis fields. Palladium is one of the most extensively used noble metals due to its outstanding properties and potential application in many catalytic reactions. However, palladium NPs tend to agglomerate on the oxide supports to reduce their high surface energy, which results in the decrease of catalytic efficiency and properties. Therefore, some approaches have been attempted and reported to deal with the problem. Choosing a suitable support is an effective consideration to obtain ideal catalysts, for example, finding the appropriate supports with monolithic macropores and hierarchical structure. Furthermore, previous studies have revealed that the strong metal–support interaction (SMSI) between the noble metal and the support could contribute to the enhanced catalytic performance of the supported metal NPs in various chemical reactions, such as hydrogenation, oxygenation, and reduction reactions. This suggests that the strong metal–support interaction (SMSI) effect paves new ways to prepare novel catalysts with high efficiency. Among the various supports, rare-earth oxide based materials can have fourteen electrons in their 4f orbital at most, leading to flexible energy levels and changeful electronic properties. Previous investigations also indicate that compared to the bulk materials, some specific morphologies such as nanorods, nanowires and nanocores show great promise in many applications. Herein, we report the first use of Er2O3 nanorods as the support for Pd loading. Erbium oxide (Er2O3), which has superior features, such as high mechanical strength, a wide band gap, substantial hardness and high thermal stability, has become one of the promising rare earth materials for several technological applications including photonics, protective coatings, optoelectronic devices and other fields. The controllable morphologies such as the shape, size and phase which show distinct electronic, optical and magnetic properties may impact catalytic properties. Nguyen et al. prepared several kinds of Er2O3 in a variety of shapes including wires, rods, bundles and flowers with different sizes (ranging from 3 nm to 3 μm) via hydro-solvothermal reactions. It is found that the optical properties of these Er2O3 samples depend not only on the crystalline phase but also on the particle size. Mohammadi et al. found that Er2O3 nanoparticles can affect the electropolymerization process by creating a porous structure of the nanocomposite, thus increasing the surface area as compared with the pure polymer. Fumiya Sato et al. prepared Er2O3 nanorods which mainly exposed the (400) and (440) facets on the surface showing excellent catalytic activity compared to commercial Er2O3 nanoparticles. M. Chavez Portillo et al. successfully developed an Er2O3–ErOOH mixture powder by chemical bath (CB) deposition. After annealing at 1000 °C, the powder showed a predominant sharp peak (222), indicating a (111) preferential orientation for Er2O3.

References

1. Structural, optical and magnetic properties of ErxZn1-xO nanoparticles: The impact of the Er-content. J. Alloys Compd. 2023; 938: 167507.

2. Exploring the optical properties of the 1.53 μm emission in Er3+-doped glass, anti-glass and ceramic in TeO2 - Ta2O5 – Bi2O3 system. Opt. Mater. 2024; 162: 112328.

3. Erbium oxide as a novel support for palladium nanocatalysts with strong metal–support interactions: remarkable catalytic performance in hydrogenation reactions.