Dysprosium Oxide Research Articles

Magneto-optical Faraday effect in dysprosium oxide (Dy2O3) based ceramics obtained by vacuum sintering.

The method of self-propagating high-temperature synthesis of submicron powders with subsequent vacuum sintering was used to produce a series of optical ceramics based on dysprosium oxide (DyxY0.95-xLa0.05)2O3, where x=0.7, 0.85, and 0.9. The influence of ceramics composition on optical transmission of the obtained samples was investigated. The studied materials had several transparency windows in the visible 500-730nm, near-IR 1900-2300nm, and mid-IR 3500-7500nm ranges. The dependence of the Verdet constant on wavelength in the 400-1940nm range was measured for each ceramics composition, and analytical approximations were obtained. When Y and La dopants were used, the Verdet constant depended linearly on the concentration of Dy3+ ions, and its value in the visible wavelength range was about twice that of the analogous value for a terbium gallium garnet crystal. The high transmission and relatively high Verdet constant make the produced materials highly promising for fabricating Faraday devices for Tm3+ and Ho3+ lasers and for lasers emitting in the visible spectrum.

Rare earth elements price forecasting by means of transgenic time series developed with ARIMA models

A time series can be thought of as a numerical organism with a continuous nature from a chronological point of view and something that is permanently updated. Up to this moment time series research related with their features, traits, and characteristics, is mainly focused on data mining, in order to discover hidden information or specific knowledge within the time series or their transformations. However, time series representation is crucial, as they are difficult to handle in their original structure due to their high dimensionality.In this paper, the “theory of transgenic time series” is developed, and applied to the forecasting of several rare earth oxide prices: dysprosium, europium, terbium, neodymium, and praseodymium oxides. This theory addresses, specifically, the existence of metal price cycles and the presence of anomalous phenomena that the theory allows to eliminate from the time series, improving the accuracy of the forecast.After representing the time series in a way that allows their genome to be sequenced, a restriction enzyme is defined in order to create a genetically modified time series. There was no need to develop DNA ligases as time series can be cut and pasted without further considerations.Results clearly state that transgenic time series lead to more accurate short term forecasts in cases where a consistent time series genome can be represented. Further research should address the feasibility of developing more accurate long term forecasts by adding new gene sequences based on the time series genome, in order to achieve greater confidence from investors and professional advisers in the feasibility studies developed for future mining investment projects.Finally, it has to be remarked that this theory has nothing to do with “genetic algorithms”, a metaheuristic that was inspired by the natural selection process and not by the sequencing and manipulation of the genome.

Blue-yellow emission adjustability with aluminium incorporation for cool to warm white light generation in dysprosium doped borate glasses

A series of white light emitting Dy3+ doped lead borate (DY) and lead alumino borate (DYA) glasses have been prepared by melt quench technique and are explored by XRD, FTIR, optical absorptions, fluorescence and density measurements. In this paper an effort has been made to compare the structural changes and luminescence efficiencies of prepared glasses by changing dysprosium oxide content and glass network environment by adding aluminium oxide. The XRD profile of all the glasses confirms their amorphous nature and FTIR study shows the presence of BO3 and BO4 groups. Incorporation of Al2O3 in the glass system is responsible for a strong effect on luminescence of the present glass system. There is a strong correlation between Dy3+ ions concentration and the host glass composition on the energy transfer mechanism. The decay curves deviate gradually from single exponential function at lower concentrations to non-exponential behavior at higher concentrations. The Inokutie Hirayama (IH) model for S= 6 fits well the non-exponential decay curves that indicate dipole-dipole type energy transfer between donor and acceptor ions. The calculated chromaticity coordinates lie in the white region of CIE 1931 chromaticity diagram and are in excellent proximity with the standard equal energy white illuminant (0.333, 0.333). Furthermore, the calculated correlated color temperature and the yellow to blue (Y/B) ratio of the synthesized photonic glasses may offer the possibility of tuning the white light by varying concentration and host environment which could be useful for various photonic based device applications.

Ball milling and sintering of neutron absorber Mo-based Tb2O3-Dy2O3 composite and its characterization

The key to gray control rods controlling and adjusting nuclear reactivity to safely operate a nuclear reactor was in their internal neutron absorbers. New types of Mo-based Tb2O3-Dy2O3 composites used as neutron absorbers were designed and then synthesized by ball milling, cold isostatic pressing and sintering. The microstructure of ball-milled powders and sintered bulks were analyzed. Ball milling induced terbium oxide and dysprosium oxide to be first fined, nano-crystallized, amorphized and finally dissolved into Mo crystal to form Mo (Tb, Dy, O) supersaturated nanocrystalline solid solution, which was driven by mechanical work, not by negative heat of mixing after thermodynamic analysis of a ternary Mo-Tb-Dy systems and the dynamic discussion of ball milling. Sintering caused Tb, Dy and O atoms precipitated from Mo crystal and then formed Tb2O3 and Dy2O3 precipitates that uniformly distributed in Mo matrix. The microhardness, compression strength, coefficient of thermal expansion of sintered bulks were measured, and the corresponding mechanism was also discussed.

Mechanochemical Synthesis of Dy2TiO5 Single-Phase Crystalline Nanopowders and Investigation of Their Properties

Crystalline nanopowders of dysprosium titanate were prepared by the mechanochemical synthesis method using anatase and dysprosium oxide as the initial reagents. The duration of the mechanochemical treatment was 180 min. The crystal structure of mechanochemically synthesized Dy2TiO5 corresponds to a high-temperature cubic modification. The particle sizes of mechanochemically synthesized dysprosium titanate were 20–30 nm. The properties of the obtained nanopowders and bulk samples consolidated from them were studied. Commercial Dy2TiO5 powders prepared by melting the oxides were used for comparison. It was found that the Dy2TiO5 phase decomposes and the metastable DyTiO3 phase is formed during the sintering of mechanochemically synthesized nanopowders, which contradicts the classical Dy2O3–TiO2 phase diagram. No phase decomposition was observed in the case of sintering of commercial Dy2TiO5 powders.

Effect of pure and REM: (Nd, Ce)-doped Dy2O3 NPs via hydrothermal method and their magnetic, optical, electrochemical, antibacterial and photocatalytic activities

Pure Dysprosium oxide (Dy2O3) with the spherical-morphology based material, and the rare earth metal (REM) - doped Dy2O3 nanoparticles (NPs) were synthesized using the reaction of dysprosium (III) nitrate pentahydrate, neodymium (III) nitrate hexahydrate and cerium (III) nitrate hexahydrate by the simple cost-effective hydrothermal method, which exhibits high antibacterial effects and photocatalytic activity. The antibacterial effect of pure and (5 mol% of Nd, Ce) - doped Dy2O3 NPs, on Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi were studied by using various concentrations. The photocatalytic activity of pure and 5 mol% of cerium doped Dy2O3 NPs were assessed by degrading the methyl orange (MO) dye under UV irradiation. The characterization results indicated that the XRD and TEM studies confirms the size of the prepared Dy2O3 NPs decreased with Nd and Ce insertion into dysprosium oxide. The particle size calculated from the Williamson-Hall (W-H) plot was consistent with TEM results. From VSM analysis, cerium doped NPs shows high saturation (Ms) magnetization than that of pure Dy2O3 NPs. The emission spectra and electrochemical properties are found to be dopant dependent. 5 mol% of Ce-doped Dy2O3 NPs shows good antibacterial effect compared to that of pure and Nd doped sample. From the above, it is observed that cerium doped NPs exhibit high photocatalytic activity than pure NPs. The mineralization of MO dye solution for pure and 5 mol% of Ce-doped samples has been confirmed by chemical oxygen demand (COD) measurements. In addition, the rate of decolorization is also confirmed by the total organic carbon (TOC) study. From the results, cerium doped sample enhances the photocatalytic performance compared to pure Dy2O3 NPs due to the lower recombination rate of electron-hole pairs and the presence of large surface area of the samples act as reactive facets for adsorption of MO dye molecules.

Determination of 8-hydroxy-2′-deoxyguanosine oxidative stress biomarker using dysprosium oxide nanoparticles@reduced graphene oxide

Electrochemical detection of 8-OHdG biomarker using Dy2O3@RGO/SPCE.

Development of a new rare-earth (Dy3+)-based thermoluminescent dosimeter

In this work, two tissue equivalent dosimeters i.e. LiF: Mg, Ti and LiF: Mg, Dy with the same concentration of Mg were synthesized by a chemical co-precipitation method. The crystallite size determined using Sherrer's formula ranged from 30nm to 35nm. The absorbance spectra revealed the presence of stretching vibrations of oxides of titanium and dysprosium in LiF: Mg, Ti, and LiF: Mg, Dy, in which oxygen was attached with Ti4+ and Dy3+ cations, respectively. LiF: Mg, Ti exhibited 5 thermoluminescent (TL) peaks corresponding to the multi-trap multi-recombination module with trap depths ranging from 2.052 to 2.89eV. In LiF: Mg, Dy, only one TL peak was observed corresponding to one-trap and one-recombination module with a trap depth ranging from 2.0318 to 2.5489eV. The dosimetric peaks of LiF: Mg, Ti occurred in the temperature range 240–260°C (peak 4) and 280–290°C (peak 5) with a maximum fading of 2.7% in 108h. The single dosimetric peak of LiF: Mg, Dy occurred in the temperature range l20–220°C with a maximum fading of 4.9% for the same duration. The minimum detected dose in LiF: Mg, Ti was 10mSv with a calibration factor of 0.08882, while in LiF: Mg, Dy, the minimum detected dose was 40mSv with a calibration factor of 0.34129. Ti-based dosimeter was found to have a linear response in the range of 10 – 10,000mSv, while, Dy-based dosimeter responded linearly in the dose range of 40 – 10,000mSv. The latter dosimeter was found to be 3 time less sensitive than the former; therefore, for personal and extremity dosimetry, the former dosimeter appeared more suitable; while for high doses, the latter dosimeter responded well.

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide

A series of glass samples with chemical formula {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1−x(Dy2O3)x where x=0.01, 0.02, 0.03, 0.04 and 0.05M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO4, BO3, TeO4 and TeO3 vibrational groups. The density of the glass systems is increased with the addition of Dy2O3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy2O3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region.

Phase evolution and microstructure characteristics of Mo-based Tb2O3-Dy2O3 composites synthesized by ball milling and sintering

Mo-based Tb2O3-Dy2O3 composites used as neutron absorbers in nuclear power reactor were synthesized by powder metallurgy. The comparative studies of Mo-based Tb2O3 and Mo-based Dy2O3 composites were carried out to deeply understand the phase evolution and microstructure characteristics of Mo-based Tb2O3-Dy2O3 composites. Ball milling induced terbium oxide and dysprosium oxide in the powder mixtures to be first fined, nano-crystallized, amorphized and finally dissolved into Mo matrix to form the supersaturated nanocrystalline solid solution that was driven by mechanical work, not by negative heat of mixing. Mo lattice parameter increased with increasing ball-milling time, opposite for Mo grain size. A phase transformation of Dy2O3 crystal from cubic to monoclinic and then to amorphous was observed during ball milling. The microhardness of sintered bulks was first increased and then decreased with increasing sintering time. The maximum value was obtained at the bulks sintered for 8 h. The microhardness and bulk density were increased with increasing sintering temperature before 1600 °C. The mechanism of ball milling and sintering was also discussed.

Absorption and emission analysis of zinc borotellurite glass doped with dysprosium oxide nanoparticles for generation of white light

A series of zinc borotellurite glass doped with Dy2O3 nanoparticles with chemical formula {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1−x(Dy2O3NP)x (where x = 0.01, 0.02, 0.03, 0.04 and 0.05M fraction) has been fabricated by using conventional melt-quenching method. In this work, absorption and emission analysis of the glass systems have been done. The absorption data are obtained from the UV–Vis spectroscopy while the emission spectrum of the glass systems is recorded by using the Luminescence spectrometer. From the absorption data, the direct and indirect optical band gaps for the glass systems are calculated. Both of the band gaps are found to decrease as opposed to the concentration of Dy2O3 nanoparticles. The decrement of the optical band gaps leads to the increment of the refractive index of the glass systems. From the emission spectra, two transition bands are observed, which represent the transition from 4F9/2 to 6H15/2 and 6H13/2. Other than that, the x and y CIE chromaticity coordinates are determined from the emission spectra and are found in the region of white light. The values of the correlated colour temperature for this glass systems are in between 4104.22 and 4886.17K and is in the neutral white light region.

Preparation of the Nanostructured Radioisotope Metallic Oxide by Neutron Irradiation for Use as Radiotracers

Metallic oxides manganese dioxide (MnO2), samarium oxide (Sm2O3), and dysprosium oxide (Dy2O3) with nanorod-like structures were synthesized by the hydrothermal synthesis method, respectively. Subsequently, the nanostructured radioisotopes MnO2 with Mn-56, Sm2O3 with Sm-153, and Dy2O3 with Dy-165 were prepared by neutron irradiation from the HANARO research reactor, respectively. The three different elements, Mn, Sm, and Dy, were selected as radiotracers because these elements can be easily gamma-activated from neutrons (activation limits: 1 picogram (Dy), 1–10 picogram (Mn), 10–100 picogram (Sm)). Furthermore, the synthesized radioisotopes can be used as radiotracers in Prompt Gamma Neutron Activation Analysis as the rare earth metals Dy and Sm were not present in the Korean environment. The successful synthesis of the radioisotope metallic oxides was confirmed by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectrometry (EDS), X-ray Diffraction (XRD) analysis, and gamma spectroscopy analysis. The synthesized nanostructured radioisotope metallic oxides may be used as radiotracers in scientific, environmental, engineering, and industrial fields.

Oxidation of organic dye using nanocrystalline rare earth metal ion doped CeO2 under UV and Visible light irradiations

Advanced Oxidation Process using semiconductor photocatalysts is an emerging technique to remove toxic organic molecules from aqueous phase. Design and development of newer photocatalytic systems are scarce in the literature. Hence, the present research focuses on rare earth doped semiconductor materials such as cerium doped dysprosium oxide was synthesized by co-precipitation method and characterised by XRD, FT-IR, UV-DRS, FESEM, EDAX analysis and HRTEM techniques. FESEM confirms that particles were spherical ranged from 23 to 31nm. EDAX confirmed the presence of Ce, Dy and O elements in the prepared photocatalysts. Photocatalytic efficiency of the prepared catalyst was evaluated in the degradation of a model organic dye such as Orange G dye under UV and Visible light irradiations. The photodegradation efficacy of the prepared material was evaluated by varying parameters like aqueous pH, catalyst dosage and dye concentration for photodegradation of the dye molecules. 15mg of photocatalyst showed excellent activity with 94% degradation under visible light and 10mg of photocatalyst showed better activity for 10ppm of OG dye with 96% for UV light irradiation under neutral pH. Kinetic studies obeys pseudo-first order reaction. The Chemical Oxygen Demand (COD) level decreases for both Visible and UV light irradiation. Effect of electrolytes such as NaCl, KCl, Na2CO3 and MgSO4 were investigated and the catalyst exhibited good activity in both UV and Visible light irradiations.

Structural evolution of non-isothermally formed dysprosium sesquioxide nanoparticles and their optical and electrical conductivity properties

Abstract This paper describes the utilization of dysprosium acetate non-isothermal decomposition as a route for Dy 2 O 3 nanoparticles preparation. Thermal events emerging during the heat treatment of dysprosium acetate was monitored using thermogravimetric analysis (TGA). The structural properties of the various solids obtained at the temperature range of 200–900 °C were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). It was found that 700 °C adequate for both the complete precursor decomposition and the crystallization process of the desired Dy 2 O 3 nanoparticles. The morphology of the obtained Dy 2 O 3 nanoparticles was examined by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Photo Luminescence (PL) was used for investigating the optical features of the obtained Dy 2 O 3 nanoparticles. Moreover, the electrical conductivity of these nanoparticles has been investigated in the temperature range of 200–500 °C.

Rare earth elements mining investment: It is not all about China

China was in the past the main driver when analysing rare earth prices and their market, since it commercialised around the 90% of the world's supply. After a cut in its exports during 2010 and 2011, rare earth prices dramatically spiked. The world's reaction to this fact was the development of a huge amount of mining projects outside China, many of whom failed when prices fell again. Nevertheless, several of them survived.This paper analyses in first place the future trend of rare earth elements prices in order to contrast the stable tendency forecasted by different providers of price assessments and market data. Secondly, it studies in deep five ready-to-go rare earths mining projects around the world: Nechalacho Project (North-west Territories, Canada); Zandkopsdrift Project (Northern Cape, South Africa); Bear Lodge Project (Wyoming, USA); Kvanefjeld Project (Southern Greenland); and Dubbo Zirconia Project (New South Wales, Australia). The main purposes being to give an “order of magnitude” both technical and economic of this specific mining industry; to provide a tool for investors, potential investors and professional advisers addressing rare earth mining investment analysis; and to facilitate the development of preliminary economic assessments of future rare earth mining projects. These aims will also help to fight against several systemic problems of the rare earth market: lack of trust, market opacity, and short versus long-term approaches and profit orientation.Conclusions clearly show that despite the complexity of rare earth mineral deposits and the fact that their mining operation usually includes different by-products, the evaluation of rare earth mining investments does not present much more difficulty than in the case of single element mining projects. Forecasted prices used in these economic studies are the Achilles’ heel of nowadays rare earth mining investment analysis.Finally, although differences in demand of different rare earth elements will make really difficult to achieve “a priori” a market in balance, the five studied projects are anticipated to cover approximately the third part of the total rare earth consumption in the world. When their dysprosium oxide production was analysed, the resulting proportion for the most critical rare earth element based on its role in clean energy together with its biggest supply risk was almost the same, something optimistic regarding the achievement of a balanced market outside China.

Pulsed Laser Ablation for Obtaining Contrast Agents Based on Dysprosium Oxide (Dy2O3) Nanoparticles

The use of the pulsed laser ablation method is proposed for obtaining solutions based on Dy2O3-nanoparticles for T2 MRI contrast agents at high magnetic fields. It has been demonstrated that the PLA method can help simplify and shorten the duration of obtaining stable Dy2O3 nanoparticle-based colloids, the relaxivity of which exceeds the relaxivity values of commercially-available MRI contrast agents.

Removing lead ions from water by using nanocomposite (rare earth oxide/alumina)

Alumina nanoparticles were prepared using reverse microemulsion method with particle size 3.8nm. Also, the precipitation method was utilized to prepare samarium and dysprosium oxides with particle size 14nm and 8.6nm respectively. Nanocomposites consist of (x)R2O3/(100−x)y−Alumina; (x=16 and 44), (R=Sm and Dy) and (y=γ and α) were prepared with milling method. The characterization of all the prepared samples was studied using XRD analyses, transmitted electron microscope (TEM) and atomic force microscope (AFM). The removal efficiency of each prepared sample was measured using the atomic absorption spectroscopy. The study has clarified that the efficiency of the nanocomposite (x)Sm2O3/(100−x)γ−alumina; x=16 to remove lead ions from water after 24h is about 99.3%.

White light emission of dysprosium doped lanthanum calcium phosphate oxide and oxyfluoride glasses

Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with dysprosium oxide were prepared by melt-quenching technique with chemical composition 20La2O3:10CaO:69P2O5:1Dy2O3 and 20La2O3:10CaF2:69P2O5:1Dy2O3. The physical, optical and luminescence properties of the glass samples were studied to evaluate their potential to using as luminescence materials for solid-state lighting applications. The density, molar volume and refractive index of the glass samples were carried out. The optical and luminescence properties were studied by investigating absorption, excitation, and emission spectra of the glass samples. The absorption spectra were investigated in the UV–Vis–NIR region from 300 to 2000 nm. The excitation spectra observed under 574 nm emission wavelength showed the highest peak centered at 349 nm (6H15/2 → 6P7/2). The emission spectra, excited with 349 nm excitation wavelength showed two major peaks corresponding to 482 nm blue emission (4F9/2 → 6H15/2) and 574 nm yellow emission (4F9/2 → 6H13/2). The experimental lifetime were found to be 0.539 and 0.540 for oxide and oxyfluoride glass sample, respectively. The x,y color coordinates under 349 nm excitation wavelength were (0.38, 0.43) for both glass samples, that be plotted in white region of CIE 1931 chromaticity diagram. The CCT values obtained from the glass samples are 4204 K for oxide glass and 4228 K for oxyfluoride glass corresponding to the commercial cool white light (3100–4500 K). Judd-Ofelt theory had also been employed to obtain the J-O parameters (Ω2, Ω4 and Ω6), oscillator strength, radiative transition possibility, stimulated emission cross section and branching ratio. The Ω2 > Ω4 > Ω6 trend of J-O parameters of both glass samples may indicate the good quality of a glass host for using as optical device application. Temperature dependence of emission spectra was studied from 300 K to 10 K and found that the intensity of the emission peak was found to be increased with decreasing of the temperature. The results of the investigations in this work confirmed that the present Dy-doped lanthanum calcium phosphate oxide and oxyfluoride glasses perform high potential for using as efficient luminescence materials for solid-state lighting applications, especially for white LEDs. Furthermore, the oxyfluoride glass sample provides more luminescence potential than the oxide glass sample.

Synthesis and characterization of Dy2O3 nanostructures: enhanced photocatalytic degradation of rhodamine B under UV irradiation

Dysprosium oxide (Dy2O3) nanoparticles have been successfully synthesized via a novel facile solvent-less solid state method. Dysprosium oxide nanostructures were prepared by heat treatment in air at 500 °C for 2 h via Schiff-base ligand as a capping agent and dysprosium source. The effect of the Schiff base ligand (N,N-Bis(salicylidene)ethylenediamine (H2salen)) as a capping agent on product by different molar ratios of dysprosium nitrate and Schiff base ligand were investigated to reach optimum conditions of Dy2O3 nanoparticles such as size and morphology. Analytical method such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, X-ray diffraction and UV–Vis diffuse reflectance spectroscopy were employed to characterized the as-prepared nanostructures. The results shows that the molar ration and calcination temperatures of Schiff base ligand and dysprosium nitrate have substantial and key effect on the size and morphology of the Dy2O3. In addition, the photocatalytic activity of Dy2O3 nanostructure was studied by the photocatalytic degradation of the rhodamine B as cationic dye under UV irradiation.

Optimum conditions for extracting rare earth metals from waste magnets by using molten magnesium

Liquid-metal extraction using magnesium as a medium was studied to examine its suitability as an environmentally friendly process for recycling rare earth (RE) metals from magnets. To determine the optimum conditions for extracting RE metals, RE extraction experiments were conducted under various conditions. Effects of extraction period, temperature, and magnesium/magnet mass ratio on RE extraction efficiency were investigated. As these parameters were increased, extraction efficiency for neodymium increased and reached almost 100%. The efficiency for dysprosium increased as well but was limited to 60%, and some dysprosium remained in the magnet. It was found that RE metals partially exist as oxide in the initial magnet. It was also found that neodymium oxide was reduced by magnesium but that dysprosium oxide was not reduced completely. RE extraction experiments with calcium added as a reducing agent were therefore conducted, and result showed that extraction efficiency for dysprosium was improved to 74%. All tolds, the optimum conditions for RE extraction (with calcium added to a magnesium/calcium mass ratio of 20) are the extraction time of six hours, the extraction temperature of 1000 °C, and the magnesium/magnet mass ratio of 10.