Rare Earth Metal Ions Research Articles

Spray-Deposited Rare Earth Metal Ion (Sm3+, Ce3+, Pr3+, La3+)-Doped CdO Thin Films for Enhanced Formaldehyde Gas Sensing Characteristics.

This study shows the electrical conductivity-dependent gas sensing characteristics of spray-deposited rare earth (RE) metal ion (Sm3+, Ce3+, Pr3+, La3+)-doped cadmium oxide (CdO) thin films on soda-lime microscope glass substrates at 300 °C. We examined the deposited films’ structural, surface microstructural, DC electrical, and gas sensing features. The X-ray diffraction study indicates that all samples were polycrystalline, with the favored growth direction shifting from the (111) plane to the (200) plane. The highest root-mean-square values were obtained for the Pr-doped CdO thin film (5.86 nm). The surface microstructure of CdO thin films was significantly influenced by the RE metal ion dopant, with typical grain size values ranging from 64 nm to 134 nm depending on the dopant. The carrier concentration and resistivity of CdO films vary based on the RE metal ions used as dopants. Low resistivity (3.01 × 10–4 Ω.cm) was achieved for the CdO thin film doped with La. High gas sensitivity (71.42%) was achieved for CdO thin films doped with La. The donor dopant regulated the electrical conductivity and gas sensing capabilities of CdO thin films.

Water-Recyclable Chitosan-Based Ion-Imprinted Thermoresponsive Hydrogel for Rare Earth Metal Ions Accumulation.

The demand for rare earth metal increases rapidly in the modern high-tech industry and therefore the accumulation of rare earth metal ions from an aqueous environment becomes a significant concern worldwide. In this paper, a water-recyclable chitosan-based La3+-imprinted thermoresponsive hydrogel (CLIT) was prepared to accumulate La3+ from solution. The CLIT was characterized by DSC, FITR, Raman spectroscopy, XPS, and SEM, which revealed obvious reversible thermosensitivity and imprinted sites of La3+ ions. An adsorption capacity of 112.21 mg/g to La3+ ions was achieved on CLIT under its optimum adsorption conditions (pH 5, 50 °C, 60 min). The adsorption could be well illustrated by second-order kinetics and Freundlich isotherm models. The La3+-adsorbed CLIT could be recycled only by rinsing with 10 °C cold water, with a desorption rate of 96.72%. After ten cycles of adsorption-desorption, CLIT retained good adsorption capability. In the solution containing six ions, the adsorption coefficients kLa3+/Mn+ of CLIT were 2.04–3.51 times that of non-imprinted hydrogel, with kLa3+/Y3+, kLa3+/Gd3+, kLa3+/Al3+, kLa3+/Fe3+ and kLa3+/Cu2+ being 1.67, 2.04, 3.15, 2.72 and 4.84, respectively.

Substituted diamides of dipicolinic acid as extractants and ionophores for rare earth metals

The variety of newly synthesized diamides of dipicolinic acid (DPA) bearing methyl- and oxymethyl substituents in various positions of phenyl ring was investigated as potential ligands for liquid–liquid extraction of rare earth metal ions and as membrane active compounds in plasticized polymeric membranes of potentiometric sensors. It is found that scandium is extracted with 2,6-pyridinedicarboxylic acid diamides similarly to heavy lanthanides, while yttrium is extracted together with light group lanthanides. DPA shows high selectivity for the separation of cadmium/zinc, lead/nickel or copper/nickel pairs. The four out of six studied ligands demonstrate significant potentiometric sensitivity towards scandium, yttrium and lanthanides in 10−7–10−3 mol/L concentration range in nitric acid solutions. The trends in sensitivity values vary depending on a ligand structure and the highest values are observed for Sc3+ and heavy lanthanides. According to the evaluated selectivity Sm3+ is the most preferred ion, while La3+ is the most discriminated. The differences in sensor behavior in rare earth metal solutions assume that such devices can be applied in sensor arrays for potentiometric analysis of lanthanide mixtures.

Selective Accumulation of Rare-Earth and Heavy Metal Ions by a Fucoidan-Inorganic Composite Material

The accumulation of rare-earth and heavy metal ions from wastewater is important for industrial technology. However, practical accumulators of metal ions are expensive with respect procurement of raw materials, synthesis, and preparation. Therefore, it is preferable to accumulate metal ions using sustainable resources, such as natural polymers. Fucoidan, a water-soluble natural polymer, is a sulfated polysaccharide from the cell-wall of brown algae. Therefore, fucoidan behaves as an acidic polysaccharide in an aqueous solution. We prepared a fucoidan-inorganic composite material by mixing fucoidan and a silane coupling reagent, bis(3-(trimethoxysilyl)propyl)amine (SiNSi). This fucoidan-SiNSi (F-SiNSi) composite material showed a water-insoluble property. This is due to the encapsulation of fucoidan into a three-dimensional network of SiNSi with siloxane bonding. When the F-SiNSi composite material is immersed in a metal ion-containing aqueous solution, the composite material accumulated the metal ions. The binding affinity of each metal ion was Ca(II), Mg(II) << Nd(III) < Cu(II), Zn(II), Ni(II), La(III) < In(III) < Y(III). Additionally, the maximum-accumulated amounts of the Nd(III), Cu(II), Zn(II), Ni(II), La(III), In(III), and Y(III) ions were 140, 200, 190, 200, 200, 230, and 270 nmol per mg of fucoidan, respectively. Furthermore, the molar ratios of the acidic groups (the sulfate and carboxyl groups) in the fucoidan and accumulated metal ions, were 0.081–0.156. Therefore, the F-SiNSi composite material showed a selectivity for rare-earth and heavy metal ions. The accumulation mechanism of the rare-earth and heavy metal ions was related to the carboxyl groups in the fucoidan.

Doping effect of rare earth metal ions Sm3+, Nd3+ and Ce4+ on denitration performance of MnOx catalyst in low temperature NH3-SCR reaction

The MnXOx catalysts (i.e., MnSmOx, MnNdOx, MnCeOx) were prepared by reverse co-precipitation method and used for NH3-SCR reaction. It is found that MnCeOx catalyst presents the best low temperature catalytic activity (higher than 90% NOx conversion in the temperature range from 125 to 225 °C) and excellent H2O + SO2 resistance. In order to explore the reason for this result, the characterization of X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflaxions infrared Fourier transformations spectroscopy (DRIFTS) were conducted. The obtained results suggest that MnCeOx catalyst shows the largest amount of acid sites and the best reducibility among these MnXOx catalysts. Besides, Ce4+ doping inhibits the crystallization of MnOx catalyst and shows the largest specific surface area. Finally, in situ DRIFTS experiments reveal that NH3-SCR reaction over MnCeOx catalyst follows both Langmuir–Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms, which is through “fast SCR” reaction.

Development of the geopolymer-based zeolite from powdery silica fume and its application in methanol to dimethyl ether

A large number of non-biodegradable powdery silica fume waste produced in industry increase the severity of environmental problems due to their potential harmfulness. The synthesis of geopolymers or zeolitic materials using powdery silica fume as silicon source has become an attractive sustainable solution to remedy this crisis. In this paper, a cost-effective porous ferrierite was synthesized by a facile hydrothermal strategy using silica fume-based geopolymer as precursor and applied to methyl dimethyl ether reaction (MTD). The specific surface area of geopolymer increased from 30.5 to 258.4 m2/g of ferrierite, and the methanol conversion rate correspondingly improved from 16.04 % to 78.5 %. Moreover, rare earth (RE) metal ions were introduced to optimize the performance, and the maximum conversions of RE-modified ferrierite were higher than 90 %. The superior catalytic performance of RE-modified ferrierite was related to the synergy of abundant porosity, acidic active sites and metal functions, which could be realized by regulating the crystallization degrees and ion exchange concentrations. Moreover, the abundant active amorphous silica in silica fume is conducive to the preparation of eco-friendly geopolymers and the further development of zeolite materials, realizing the high value-added utilization of solid wastes.

Physicochemical properties and thermal-responsive phase separation of poly(ethylene glycol)-based ionic liquids

• A series of PEGylated ionic liquids were synthesized. • Physico-chemical properties of PEGylated ionic liquids were measured. • AOT-based PEGylated ILs exhibit good surface activity in aqueous solutions. • PEGylated ionic liquids exhibit typical low critical solution temperature phase behavior. • Thermal-regulated phase separation system has great promise to separate metal ions. How to design thermal-responsive functional ionic liquids that can respond in a reversible manner still remains a challenge for the construction of ionic liquid-based smart systems, and they easily find applications in various scientific fields, including phase transfer catalysis, smart soft materials, controlled drug delivery and green separation. In this work, a series of PEGylated ionic liquids were prepared, and their structures were confirmed by NMR and FTIR spectra. The thermal properties of these ionic liquids were characterized by DSC and TGA. In addition, their physicochemical properties were measured in detail, including density and viscosity. Different models were used to fit the density and viscosity data. The critical micelle concentrations of the Aerosol OT-based PEGylated ionic liquids were also determined by the surface tension method, and they exhibited good surface activity. Furthermore, these PEGylated ionic liquids exhibit typical low critical solution temperature phase behavior. To illuminate the underlying mechanism of thermal-induced phase separation, temperature-dependent FTIR spectra were used to analyze the interaction between ionic liquids and water molecules. Finally, the thermally regulated PEGylated IL phase separation system was proposed as an efficient strategy to separate heavy metal ions and rare earth metal ions from water media. The results presented here offer key information to design new thermoresponsive ionic liquids and their applications.

Electroanalytical measurements of lanthanum (III) chloride in molten calcium chloride and molten calcium chloride and lithium chloride

Cyclic voltammetry (CV), square wave voltammetry (SWV) and other electroanalytical methods have been applied to molten chloride salts to study metal ion behavior. These studies have been useful for understanding and optimizing the electrowinning of metals. Notable ions that have been studied are rare earth and actinide metal ions in LiCl-KCl salts. However, the behavior of lanthanum (La3+) ions in some molten chlorides or chloride mixtures (e.g., CaCl2) has not been studied. CV experiments were conducted to evaluate La3+ behavior in CaCl2-LiCl and CaCl2 and were compared to La3+ behavior in LiCl-KCl and CaCl2-NaCl eutectics from other studies. The electrochemical reaction was checked for reversible, quasi-reversible, and irreversible transitions in scan rate by examining the relationship between the scan rate applied and the peak current and potential for La3+ reduction. Properties such as diffusion coefficient (Do) and electrons exchanged (n) were calculated from data. The electrochemical setup was also checked for radial diffusion based on the calculated La3+ diffusion coefficient and electrode radius, which led to the observation that natural convection possibly affected the La3+ reduction peak at low scan rates. For more accurate electroanalytical measurements of La3+ reduction, CV curves with and without LaCl3 added to CaCl2 and CaCl2-LiCl were compared to establish baselines for the La3+ reduction peak. The impact of resistance (IR) compensation on the La3+ reduction peak was also explored. Techniques and practices that improved electroanalytical measurements include placing the electrolytic cell in a Faraday cage, distancing electrodes from the heating coils, and melting the chlorides twice prior to measurements.

Structural and electronic properties of double perovskite ruthenates; A2GdRuO6 (where A = Ba, Sr)

We report the findings of an experimental and theoretical analysis of the structural, electronic, and vibrational characteristics of Ba 2 GdRuO 6 and Sr 2 GdRuO 6 double perovskite ruthenates. The samples of Ba 2 GdRuO 6 and Sr 2 GdRuO 6 were synthesized using solid state reaction method. The samples have been characterized by X-ray diffraction (XRD) technique where phase purity and space group information have been obtained using FullProf Rietveld refinement method. The Rietveld-fitted XRD patterns show that Ba 2 GdRuO 6 has a single-phase cubic structure with space group F m 3 ¯ m and that Sr 2 GdRuO 6 has a monoclinic structure with space group P 2 1 ∕ n . The vibrational properties were measured, via. , Raman spectroscopy performed at room temperature. The structures predicted from XRD were studied theoretical using accurate plane wave pseudo-potential method based on density functional theory (DFT) with Hubbard parameter, U (DFT+U). The Ba 2 GdRuO 6 is found to be metallic with difference in density of states for spin up and spin down electrons; whereas Sr 2 GdRuO 6 is insulating with a band gap of 4.0 eV. The vibrational analysis of pervoskites shows A 1 g , E g and 2 F 2 g , Raman active modes for Ba 2 GdRuO 6 ; while for Sr 2 GdRuO 6 the observed active modes were A g and B g , respectively . It’s worth noting that the experimentally measured values match those predicted by our DFT calculations. • An integrated experimental and theoretical approach for Ru based double perovskites has been discussed. • Future perspective to explore the role of rare-earth metal ions to further tune the electronic properties of such perovskites has been discussed. • The interesting interplay between Ru and transition metal ions can be understood as a transition from metallic for Ba 2 GdRuO 6 to insulating behavior for Sr 2 GdRuO 6 .

Carboxyl functional poly(ionic liquid)s confined in metal–organic frameworks with enhanced adsorption of metal ions from water

Development of porous adsorption materials tethered with functional groups was favorable to establish a more efficient, stable and broad-spectrum metal ions removal strategy from water. In this work, carboxyl functional poly(ionic liquid)s@MOF composites were prepared through in situ polymerization of ILs monomers inside MOF pores. Their thermophysical property, structure and morphology were characterized by different techniques. These PILs@MOF composites were proposed as universal and efficient adsorbents to remove selected rare earth metal ions (La3+, Sm3+, Nd3+) and heavy metal ions (Pb2+, Cd2+) from water medium. Effect of pH value and composite dosage on the adsorption efficiency were studied in detail. The optimized adsorption efficiency as high as 99.8 % could be found for the selected metal ions by PIL@MIL-101. In addition, the isotherms, kinetics and thermodynamic parametersof the adsorption process were also determined, and these results imply that the Langmuir model and pseudo-second-order model fitted well with the experimental data. Thermodynamic parameters revealed spontaneous and exothermic nature of the adsorption process. A plausible mechanism for the adsorption process was suggested by the electrostatic interaction and coordination between the carboxyl group and metal ions with the aid of FTIR and XPS measurements. Finally, recycling experiments were performed to demonstrate the recyclability and stability of PIL@MOF composites undergoes at least five adsorption–desorption runs. The current research presented a series of poly(ionic liquid)s@MOF composites as a universal adsorption platform that demonstrated great potential for removing metal ions with remarkable efficiency.

Strain-induced magnetic anisotropy of REIG thin films grown on YAG(111) substrates by pulsed laser deposition

Several studies have revealed using rare earth (RE) elements instead of yttrium to regulate the strain-induced magnetic anisotropy of garnet films in recent years. In this study, we used pulsed laser deposition to fabricate RE iron garnet (REIG) thin films on (111)-oriented yttrium aluminum garnet (YAG) substrates. The REIG films are 100 nm in thickness and crystalline with (111)-orientation. The out-of-plane (444)-plane spacing decreases as the ionic radius of RE metal ions decreases, while the crystallite size increases. Samarium, holmium, and yttrium iron garnet (SmIG, HoIG, and YIG) have out-of-plane compressive strain, while erbium and thulium iron garnet (ErIG and TmIG) have weak out-of-plane tensile strain. The strain of the REIG films is resulted from lattice mismatch, off-stoichiometry, and the recrystallization process by thermal annealing. SmIG has a rather rough surface because of the crystalline distortion due to the largest ionic radius of Sm and the lattice mismatch between SmIG and YAG substrates. Due to negative magnetostriction constant and out-of-plane compressive strain, SmIG and HoIG films show strong perpendicular magnetic anisotropy (PMA) in vibrating sample magnetometry and magneto-optical Faraday effect (MOFE). MOFE also revealed that the REIG films have different sensitivities at different wavelengths of light. With further tuning PMA on SmIG and HoIG by decreasing the thickness and lateral size, our findings could pave the way for high-density nano-scale magnetic information storage based on REIG thin films.

Rare-Earth (RE = Y, Gd, Tb, Dy, Ho, and Er) Chains Bridged with a Triplet Biradical and Magnetic Hysteresis Recorded for RE = Tb.

Complex formation of 5-tert-butyl-1,3-phenylene bis(tert-butyl nitroxide) and rare-earth (RE) metal ions gave a linear chain where each nitroxide O atom is directly bonded to the RE ion. The bridge was proven to be a ground triplet molecule in the complexes. A hysteresis loop was recorded below 2.8 K as a single-chain magnet for the RE = Tb derivative.

The selective adsorption of rare earth elements by modified coal fly ash based SBA-15

The modification of fly ash based SBA-15 enables the selective adsorption of REE(III) with a high capacity. • The species distribution of rare earth elements ions was simulated. • DTPADA-SBA-15 owned high adsorption efficiency and selectivity for REE (III). • DTPADA-SBA-15 owned preferable reusability in acidic solution. Rare earth elements (REE) are strategic resources and the recycling of REE in alternative resources is urgent and gets increasingly attention. However, the separation of REE in these alternative resources is still a challenge due to the low concentration of REE and multi coexisted ions in acidic system. In this study, the species distribution of REE within the pH 0–8.0 was calculated. The SBA-15 originated from coal fly ash was modified by two steps with (3-aminopropyl) triethoxysilane (APTES) and diethylenetriaminepentaacetic dianhydride (DTPADA) to obtain DTPADA-SBA-15 adsorbent, which was applied to the selective adsorption of REE. The results showed that DTPADA-SBA-15 possessed excellent adsorption performance on the selective adsorption of REE, including Eu, Gd, Tb, Nd and Sm, in acidic solution (pH 2) with multi competing ions. The FT-IR and Zeta potential characterization verified that the chemical adsorption through the coordination of O in DTPADA-SBA-15 with REE was dominant at lower pH value. The study of adsorption kinetics indicated that the adsorption of rare earth metal ions followed pseudo-second-order kinetic, of which the adsorption process followed the Langmuir isotherm model.

Giant Crown-Shaped Dy34 Nanocluster with High Acid-Base Stability Assembled by an out-to-in Growth Mechanism.

Lanthanoid metal ions have large ionic radii, complex coordination modes, and easy distortion of coordination spheres, but the design and synthesis of high-nucleation lanthanoid clusters with high stability in solution (especially aqueous solution) are challenging. Herein, a diacylhydrazone ligand (H2L1) with multidentate chelating coordination sites was used to react with Dy(OAc)3·4H2O under solvothermal conditions to obtain an example of a 34-nucleus crown-shaped dysprosium cluster [Dy34(L)8(μ2-OH)(μ3-OH)21(μ3-O)14(OAc)31(OCH3)2(H2O)15](OAc)3 (1). Structural analysis showed that the bisacylhydrazone ligand H2L1 with polydentate chelate coordination sites could rapidly capture DyIII ions, thereby forming 34-nucleus crown-shaped dysprosium cluster 1 following the out-to-in growth mechanism. Cluster 1 remained stable after immersion in solutions with different pH values (3-14) for 24 h. To the best of the authors' knowledge, high-nucleation lanthanoid clusters with excellent strong acid and base stability and water stability are very rare. Meanwhile, high-resolution electrospray mass spectrometry molecular ion peaks produced by cluster 1 were captured, which proved to be stable also in organic solvents. Magnetic research showed that cluster 1 exhibited frequency-dependent behavior. This work provides a new idea for designing and synthesizing high-nucleation lanthanoid clusters with high stability.

In-situ infrared spectroscopic study of the mechanism of the low temperature selective catalytic reduction of NO surface by Mn/ bastnaesite concentrate

The Mn/bastnaesite concentrate and Mn/Al2O3 catalysts were prepared by impregnation method, and their NH3-SCR denitrification performance was tested. The results showed that the Mn/bastnaesite concentrate catalyst achieved up to 95% NO conversion rate at 150 °C, and the Mn/Al2O3 catalyst reached 76% at 300 °C. A series of characterisation results showed that the bastnaesite concentrate can better interact with MnOx species and promote mutual dispersion compared to Al2O3. The Mn/bastnaesite concentrate has a stronger redox capacity, and good NH3 and NO adsorption capacity at low temperatures. The multi-element coexistence system of bastnaesite concentrate itself is a significant advantage of its use as a carrier. In-situ Fourier transform infrared (FTIR) results showed that the Mn/bastnaesite concentrate catalyst follows an L-H mechanism throughout the reaction, with NH4+ species in the Brønsted acidic site on the catalyst surface being the main reactant species. Most of NO is converted to monodentate nitrite, which is formed by bonding with Mn3+ provided by the supported Mn species, rare earth elements and transition metal ions contained in the carrier itself to form O–N–O–Mn3+ intermediates, which participate in the reaction together, and then combined with the adsorbed NH4+/NH3 species to produce N2 and H2O. An E-R mechanism was also present on the catalyst surface, NO participates directly in the reaction in gaseous form, and the NO [NH2](ads) intermediate species produced by interaction with NH4+ species in the acidic position of Brønsted was further decomposed to N2 and H2O. By comparing the reaction mechanism with the commonly used catalyst carrier Al2O3 for NH3-SCR, it can be concluded that bastnaesite concentrate as a carrier not only has the performance of conventional carriers, but also has certain catalytic activity and can interact with the active components to give it excellent performance, which provides a theoretical basis for rare earth minerals as denitrification catalysts.

Two-dimensional rare-earth-metal coordination polymers based on biphenyl-3,3',5,5'-tetracarboxylic acid displaying luminescence.

Two coordination polymers were rationally designed and successfully constructed using the rigid multicarboxylic acid ligand biphenyl-3,3',5,5'-tetracarboxylic acid (H4BPTC) and rare earth metal ions (Eu3+ and Ho3+) under solvothermal conditions. The compounds are poly[[tetra-μ2-acetato-bis(μ6-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraeuropium(III)] dimethylacetamide disolvate dihydrate], {[Eu4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·2C4H9NO·2H2O}n, and poly[[tetra-μ2-acetato-bis(μ6-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraholmium(III)] pentahydrate], {[Ho4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·5H2O}n, Single-crystal X-ray diffraction analysis reveals that both polymers possess a two-dimensional structure and they also display good thermal stability up to ca 280 °C and photoluminescence with an orange-red light emission.

Study of cation distribution in La3+ and Eu3+ substituted cobalt ferrite and its effect on magnetic properties

The rare-earth metal ion substitution in the spinel ferrites significantly alters its cation distribution, leading to changes in their structural and magnetic properties. Herein, we have studied the structural and magnetic behaviour of rare-earth (RE = La3+ and Eu3+) substituted cobalt ferrites (CoFe2-xRExO4; x = 0.03 per f.u.) synthesized using the conventional solid-state route. Both the samples possess a cubic structure with Fd3¯m space group. Substituting La3+ and Eu3+ creates a structural distortion and compresses the lattice parameter and unit cell volume of CoFe2O4 due to their large ionic radii compared to Fe3+. Raman spectroscopy pattern confirms the cubic structure of the samples; however, the variation in the intensity of A1g modes suggests the occurrence of cation redistributions. The inversion parameter (i) value calculated using the Mössbauer spectroscopy is 0.78, suggesting that pristine CoFe2O4 has a mixed spinel state. Furthermore, the ‘i’ value decreased to 0.69 and 0.66, respectively, upon incorporating La3+ and Eu3+ cations, confirming the occurrence of cation redistributions in the samples. Besides, the decreased probability of super-exchange interaction and reduction in the magnetic behaviour are caused by the migration of Co2+ cation from the octahedral-[B] site to the tetrahedral-(A) site and partial replacement of Fe3+ ion by RE3+ elements.

Mitigating the Jahn-Teller distortion driven by the spin-orbit coupling of lithium manganate cathode

Spinel LiMn2O4 is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources. However, the wholesale application of LiMn2O4 is predominately plagued by its severe capacity degradation, mainly associated with the innate Jahn-Teller effect. Herein, single-crystalline LiMn2O4 with Eu3+ doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO6 octahedra and accommodating localized electron, based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions. Notably, the stretching of MnO6 octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn2O4 is effectively suppressed, confirmed by theoretical calculation. Meanwhile, the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition, proved by synchrotron radiation absorption spectrum and operando X-ray diffraction. The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011% capacity drop per cycle even at 5C. Given this, this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.

A mini-review on rare earth metal doped ZnO nanomaterials for photocatalytic remediation of waste water

The mineralization and degradation of organic compounds present in waste water by heterogeneous photocatalysis has gained wide attention due to its effectiveness and tenancy to utilize UV-Visible solar light spectrum. The chemical stability, non-toxic character, magnificent electrical and optical properties have been recognized the ZnO as useful material for waste water treatment in environmental remediation technology. However, photocatalytic activity of ZnO limited to ultraviolet region because of its wide band gap (3.37eV). ZnO wide band gap obstruct photo-excitation for actual photocatalytic applications under abundant, safe and clean solar energy source. Many methods have been evolved in last decades to overcome this barrier. ZnO surfaces have been tailored with rare-earth metals to enhance its optical, surface and photocatalytic properties by different research groups. The doping with rare-earth metal ions enhanced the efficiency of ZnO photocatalyst by reducing band gap and shifted the absorbed wavelength to the visible region. This review paper compiles the attempts on modification of ZnO and their effect on photocatalytic activities by using rare earth metals.

Transparent materials based on semiconducting ZnO: glass-ceramics and optical ceramics doped with rare-earth and transition-metal ions

The structure of ZnO based transparent glass-ceramics prepared from glasses by controlled crystallization and of optical ceramics prepared by uniaxial recrystallization hot pressing and doped with rare-earth (RE) and transition metal (TM) ions are compared.Regions of structural inhomogeneity are formed in glasses during their casting, cooling and annealing. Their composition depends on the type and concentration of TM and RE ions and determines the difference in phase assemblage of glass-ceramics. In optical ceramics, RE ions do not enter the structure of ZnO crystals, but are located on their surface and form the RE2O3 phase. The RE2O3 fraction increases proportionally to the RE ion doping level. ZnO glass-ceramics and optical ceramics doped with TM and RE ions are multiphase materials.