12008-27-4Relevant articles and documents
A new synthesis route to light lanthanide borides: Borothermic reduction of oxides enhanced by electron beam bombardment
Latini, Alessandro,Di Pascasio, Francesco,Gozzi, Daniele
, p. 311 - 313 (2002)
Borothermic reduction of oxides enhanced by electron beam bombardment was discussed. The synthesis was carried out in vacuum and annealing was also performed. Results showed that this process has several advantages over the other synthesis procedures such as it is simple and take relatively short time, the product is crystalline and easily purified and the electron beam source permits both the synthesis and thin film deposition of the reaction product.
Doping effect of Pr6O11 on superconductivity and flux pinning of MgB2 bulk
Pan,Shen,Li,Cheng,Zhao
, p. 1555 - 1560 (2007)
Bulk samples of MgB2 doped with 0, 1, 3, and 5 wt% Pr 6O11 nanopowder were prepared using a solid-state reaction route. The lattice constants of Pr6O11-doped MgB 2 systematically increase with increasing doping level, indicating a partial substitution of Pr for Mg in the crystal structure, and consequently, the superconducting transition temperature, Tc, of MgB2 is slightly suppressed. At a low doping level of 1 wt% Pr6O 11, the critical current density, Jc, and the irreversibility field, Hirr are improved. However, at higher doping levels, Pr6O11 doping seems harmful for the performance of MgB2 in high magnetic fields. It is argued that the effect of the doping mechanism of Pr6O11 on T11 and J c is quite different from those of other rare-earth elements, such as Y or Dy.
High-Pressure Synthesis of Light Lanthanide Dodecaborides (PrB12 and CeB12): Effects of Valence Fluctuation on Volume and Formation Pressure
Yusa, Hitoshi,Iga, Fumitoshi,Fujihisa, Hiroshi
, p. 2568 - 2575 (2022/02/10)
Light lanthanide dodecaborides, RB12 (R = Pr and Ce), were synthesized from a stoichiometric mixture of hexaborides and boron using a laser-heated diamond anvil cell under high-pressure and high-temperature conditions. Contrary to the expectation that lighter lanthanide elements require higher pressure to crystallize RB12, in situ X-ray diffraction experiments reveal that cerium dodecaboride crystallizes at 26 GPa, which is significantly lower than that required to form the heavier praseodymium dodecaboride (35 GPa). In addition to the lower formation pressure, an anomalous volume reduction is also observed in CeB12, which can be explained by a valence fluctuation between Ce3+ and Ce4+ indicated by X-ray absorption near-edge structure measurements. A polyhedral coordination change from a truncated cube in RB6 to a truncated octahedron in RB12 and associated shortening of the R-B bond length result in an increase in bulk modulus and hardness.
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.
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 (2008/10/08)
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
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.
