12008-23-0Relevant articles and documents
Floating zone growth and high temperature hardness of rare-earth hexaboride crystals: LaB6, CeB6, PrB6, NdB6, and SmB6
Otani,Nakagawa,Nishi,Kieda
, p. 238 - 241 (2000)
Single crystals of rare-earth hexaborides, LaB6, CeB6, PrB6, NdB6, and SmB6, were prepared by the floating zone method. Their crystal quality increased as the atomic number of the rare-earth metals in
A new route for the synthesis of NdB6 powder from Nd2O3-B4C system
Liu,Lu,Qin,Zhang
, p. 337 - 341 (2007)
The neodymium hexaboride NdB6 powder has been synthesized by the reduction of Nd2O3 with B4C from Nd2O3-B4C system under the conditions of high temperature and high vacuum. Thermodynamic and dynamic analyses show that synthetic temperature and partial pressure in the furnace are the most important determinants during the synthesis. According to the results of thermodynamic calculation and differential scanning calorimetry (DSC), the synthetic process was determined. The compositions of products achieved at different temperatures and different holding times were identified by X-ray diffraction (XRD). The characters of powder were observed by scanning electronic microscope (SEM). It is concluded that after a series of pretreatments, NdB6 powders are fabricated from Nd2O3-B4C system under the conditions of 10-2 Pa vacuum and 4 h holding time with synthetic temperature above 1773 K. The diameter of NdB6 ranges from 2 to 4 μm.
Nano-sized neodymium hexaboride: Room temperature mechanochemical synthesis
Simsek, Tuncay,Avar, Baris,Ozcan, Sadan,Kalkan, Bora
, p. 217 - 223 (2019)
A rapid and easy synthesis of pure neodymium hexaboride, NdB6 nanocrystals was developed, without applying heat treatments at high temperatures. The mechanochemical synthesis of NdB6 powders was performed at room temperature inside a planetary ball mill. The Nd, B2O3 and Mg starting blends were mixed, and subsequently mechanically alloyed to constitute NdB6-MgO as final products. The effect of milling duration on the NdB6 formation mechanism and metallothermic reduction was investigated. Following mechanochemical synthesis, MgO was removed from the system by leaching the powders with CH3COOH solution. The formation of NdB6 phase was monitored by the X-ray diffraction (XRD) analysis. Microstructure and morphology of the synthesized nanocrystals were characterised by using scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS), and high resolution transmission electron microscopy (HRTEM) techniques. Pure NdB6 nanocrystals with a crystallite size of 18.2 ± 2.0 nm were obtained after 15 h of milling. Microscopic investigations revealed the irregular shape and morphology of NdB6 nanocrystal structures. Rietveld refinements confirm the cubic structure (space group Pm-3m) with a lattice constant of 4.1254 (2) ? and 92 ± 8 nm particle size of NdB6 phase. The Raman active phonons of Pm-3m symmetry were characterised by Raman spectroscopy.
Solar control dispersions and coatings with rare-earth hexaboride nanoparticles
Takeda, Hiromitsu,Kuno, Hiroko,Adachi, Kenji
, p. 2897 - 2902 (2009/02/05)
Nanoparticle dispersions of rare-earth hexaborides have been prepared using a media agitation mill and have been examined for optical properties. High visible light transmittance coupled with strong absorption in the near-infrared (NIR) wavelengths suitable for solar control windows are reported for hexaboride nanoparticle dispersions with particle size dependence and the effect of artifacts. Nanoparticulate LaB6 shows the largest NIR absorption among rare-earth hexaborides. NIR absorption is considered to arise from the free electron plasmon resonance. On decreasing the particle size below 120 nm, both visible light transmittance and NIR absorption are found to increase gradually until the size of 18-26 nm when they reach the maximum, and then decrease again at below 18 nm. Zirconia contamination and formation of lanthanum oxide were found to be involved during the milling process, leading to small additional absorptions around 300 and 650 nm, respectively.
