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Transparent Ceramics
Published in Debasish Sarkar, Ceramic Processing, 2019
Samuel Paul David, Debasish Sarkar
Nano-sized powders of Y2O3, Lu2O3 and YAG are prepared by the precipitation method to obtain transparent ceramics for laser applications. Such powders with good crystallinity, homogeneity and high purity with a single phase have been prepared at lower temperatures compared to the solid-state reaction method. Even though Ikesue et al. [6]. made the first laser ceramics using powders of sizes less than 2 µm produced by the solid-state reaction method, Konoshima Chemicals adopted a co-precipitation process to synthesize ultra-fine powders of Nd:YAG at a lower temperature. In chloride-based precursors, the chlorides of yttrium (YCl3), aluminum chloride (AlCl3) and neodymium chloride (NdCl3) are dissolved in water and mixed well, added slowly and mixed with an aqueous solution of either ammonium sulfhate ((NH4)2SO4) or ammonium hydrogen carbonate (NH4HCO3) of a given concentration.
Compositional Optimization and New Processes for Nanocrystalline NdFeB-Based Permanent Magnets
Published in Sam Zhang, Dongliang Zhao, Advances in Magnetic Materials, 2017
In 2001 Murray et al. experimentally produced Nd2Fe14B nanoparticles by sol–gel followed by reduction-diffusion [110]. The sol–gel technique was used to synthesize a chemically homogenous oxide; reduction-diffusion of this oxide can produce Nd2Fe14B magnetic nanoparticles. Particle growth can be minimized by controlling the reaction temperature and time. As a result, fine Nd2Fe14B nanoparticles of ∼25 nm size were successfully obtained by this method. In details, neodymium chloride hexahydrate (NdCl3.6H2O, 99.9%), iron chloride hexahydrate (FeCl3.6H2O, 97%–102%), boric acid (H3BO3, 99.8%), citric acid (99.5%), and ethylene glycol (99%) were used for synthesis of Nd–Fe–B oxide powder by a Pechini-type sol–gel process. Nd2Fe14B powder was prepared by mixing Nd–Fe–B oxides powder with 1.5 wt.% of CaH2 and annealing at 800°C for 2 h in vacuum. CaH2 (90%–95%, Sigma aldrich) was used as the reducing agent instead of calcium metal due to the ease of mixing and pulverization caused by hydrogen gas released during heating; this results in greater surface area and accelerates reduction. In this process, the major byproduct, calcium oxide (CaO) was removed by water. This technique can be readily extended to the synthesis of exchange-coupled magnetic nanoparticles to obtain high-energy product magnets.
Enhanced UV assisted photocatalytic activity of doped and co-doped SnO2 nanostructured material
Published in Particulate Science and Technology, 2023
T. Regin Das, M. Meena, I. Vetha Potheher
A surfactant-free one-step hydrothermal method to prepare pure, doped, and co-doped SnO2 NPs is processed in our laboratory. The experimental procedure used for the synthesis of SnO2 NPs is described as follows. Initially, 100 ml of double-distilled (DD) water was taken in a beaker, and the calculated amount (4.51 g) of SnCl2 was dissolved by continuous stirring. The urea (3.603 g) was then dissolved separately in 100 ml DD water. Both solutions were stirred separately for 15 min using a magnetic stirrer. Then the solutions were mixed completely with continuous stirring for 30 min. The doping is done in the initial stage, 1% Nickel Chloride (NiCl2) is added for Ni doping, 1% Neodymium Chloride (NdCl2) is added for Nd doping and 1% of each (NiCl2 and NdCl2) is added for co-doped samples. Dopants are added to the stannous chloride solution during stirring. Simultaneously, NaOH solution was added dropwise to attain the pH value of 13. The light milky solution obtained was then transferred to a borosilicate pot and placed into the microwave oven. Microwave irradiation was carried out until the reaction was completed. Once the solvent has completely evaporated, the product is collected as a yield.
Syntheses and structures of three organic–inorganic hybrids with Different 2D structural types constructed from rare earth polymers and Keggin-Type Silicotungstates
Published in Inorganic and Nano-Metal Chemistry, 2018
Suzhi Li, Huafeng Li, Huihui Luo, Ying Liu, Cuixia Ling, Fuli Zhang, Zhongyi Li, Chi Zhang, Guangxiu Cao, Bin Zhai
1–3 were synthesized successfully by reaction of the three components K4[SiW12O40]·17H2O, H2pddc/H2pzdc and a source of the respective RE ions praseodymium (III), neodymium(III), yttrium(III) in mixed CH3CH2OH/H2O solution.[16] The isolated yields for 1–3 are in the range of 45–50%, indicating that the formation of the RE-based POMs in a heated CH3CH2OH/H2O solution is strongly favored. In the preparations of 1–3, two aspects on the syntheses should be ponited out herein: (1) although the synthetic conditions and procedures of 1, 2 and 3 are almost the same, their pH values of reaction systems are somewhat different; 1 and 2 were prepared using the materials of praseodymium/neodymium chloride while 3 was made adopting yttrium nitrate; obviously, different RE salts lead to different pH values, and the difference of pH values of reaction systems lead to the discrepancy of their structures. (2) Organic ligands play an important role in the formation of different structures; when H2pddc ligand was employed, compounds 1 and 2 formed (Scheme 1a); when H2pddc ligand was replaced by H2pzdc, compound 3 was obtained (Scheme 1b); when pyridine-2,6-dicarboxylate (H2pydc) was introduced to this system, a series of RE-based/POMs-templated 3D metal-organic frameworks were isolated, which have been prepared in another article (Scheme 1c).[17]
D2EHPA treated resin for the extraction of rare earth elements
Published in Indian Chemical Engineer, 2022
Benadict Rakesh, Anupam Sourav Patel, Shashi Kumar Rana, Togapur Pavan Kumar
Macroporous chloromethylated styrene divinyl benzene resin supplied by M/s. Thermax Pvt., Ltd., was used for the experiments. Praseodymium chloride hydrate (99.9%) and neodymium chloride hexahydrate (99.9%) supplied by M/s. Sigma Aldrich Chemicals were used as such for the extraction studies. Di-2-ethyl hexyl phosphoric acid was procured from M/s. Heavy Water Board, India. Hydrochloric acid and sulphuric acid obtained from M/s. Thermo Fisher Scientific were used for the experiments. Double distilled water was used for the preparation of stock and standard solutions.