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 boron-rich rare-earth boride NdB6 under high pressure and high temperature
Zhao, Xudong,Liu, Xiaoyang,Lin, Feng,Liu, Weina,Su, Wenhui
, p. 247 - 250 (1997)
The boron-rich jare-earth boride NdB6, which is a pure phase without the intergrowth of other phases, has been obtained for the first time by the reduction of rare-earth oxide with elemental boron under the extreme conditions of high pressure and high temperature. The synthesis can be carried out in air from the beginning to the end without the protection of inert gas, and the synthesis can be completed rapidly. The residual rare-earth oxide and the elemental rare-earth metal produced in the process of synthesis can be easily removed by leaching them in HCl.
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.
Large-scale synthesis of neodymium hexaboride nanowires by self-catalyst
Ding, Qiwei,Zhao, Yanming,Xu, Junqi,Zou, Chunyun
, p. 53 - 56 (2007)
Large scale NdB6 nanowires have been successfully fabricated for the first time using a self-catalyst method with Nd powders and boron trichloride (BCl3) gas mixed with hydrogen and argon. X-ray diffraction, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) were used to characterize the samples. Transmission electron microscopy (TEM) reveals that the NdB6 nanowires are single crystals with cubic structure. Our investigation forms part of a series of studies for finding comparatively inexpensive methods to prepare RB6 nanomaterials.
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.
Direct low-temperature synthesis of RB6 (R=Ce, Pr, Nd) nanocubes and nanoparticles
Zhang, Maofeng,Wang, Xiaoqing,Zhang, Xianwen,Wang, Pengfei,Xiong, Shenglin,Shi, Liang,Qian, Yitai
, p. 3098 - 3104 (2010/04/02)
Rare-earth hexaborides (RB6, R=Ce, Pr, Nd) nanocrystals were prepared by a facile solid state reaction in an autoclave. Single-crystalline RB6 nanocubes were fabricated at 500 °C starting from B2O3, RCl3/s
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.
Heat capacity of praseodymium and neodymium hexaborides over the temperature range 5-300 K
Novikov
, p. 1550 - 1552 (2007/10/03)
The isobaric heat capacity of PrB6 and NdB6 was measured over the temperature range 5-300 K. The lattice and excess components of the heat capacity were calculated. The excess component was attributed to the Schottky contribution.
Heat Capacity and Thermodynamic Functions of Neodymium Hexaboride in the Range 5-300 K
Sirota,Novikov,Antipov
, p. 907 - 909 (2008/10/08)
Heat capacity of neodymium hexaboride was measured in the temperature range 5-300 K. The results were used to calculate the enthalpy, entropy, and Gibbs energy of NdB6 as functions of temperature. The anomaly in heat capacity revealed at 7.703 K is attributed to antiferromagnetic ordering. The temperaturedependent magnetic contribution to the entropy of NdB6 is estimated.
Thermodynamic properties of the rare earth borides and carbides in a wide temperature range
Bolgar, A. S.,Muratov, V. B.,Blinder, A. V.,Kryklya, A. I.,Suodis, A. P.
, p. 127 - 128 (2008/10/08)
For the first time a systematic study was made of the heat capacity and enthalpy of the rare earth tetra- and hexaborides and sesqui- and dicarbides in the temperature range 60-2300 K.
