Crossover from low-temperature itinerant to high-temperature localized electron behavior in the electron-doped rare-earth metal cobaltate perovskites

2011 ◽  
Vol 83 (8) ◽  
Author(s):  
S. L. L. M. Ramos ◽  
M. Oguni ◽  
Y. Masuda ◽  
Y. Inada
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Low Temperature ◽  
Rare Earth Metal ◽  
Earth Metal

The Mo2FeB2- and Mn2AlB2-Type Modifications of RE2Ni2Cd (Re = La, Pr, Nd, Sm, Tb, Dy)

2005 ◽  
Vol 60 (3) ◽  
pp. 271-276 ◽  
Author(s):  
Thomas Fickenscher ◽  
Ute C. Rodewald ◽  
Dirk Niepmann ◽  
Ratikanta Mishra ◽  
Marcus Eschen ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Low Temperature ◽  
Rare Earth Metal ◽  
High Frequency ◽  
Earth Metal ◽  
Two Dimensional ◽  
Space Group ◽  
X Ray ◽  
Sample Chamber

The rare earth metal (RE)-nickel-cadmium intermetallics RE2Ni2Cd (RE = La, Pr, Nd, Sm, Tb, Dy) were prepared from the elements in sealed niobium or tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. They crystallize with a tetragonal Mo2FeB2 type low-temperature modification, space group P4/mbm, and an orthorhombic Mn2AlB2 type hightemperature modification, space group Cmmm. The cadmium compounds were characterized through their X-ray powder patterns. Five structures of the low-temperature modifications were refined from X-ray single crystal diffractometer data: α = 763.76(9), c = 387.26(8) pm, wR2 = 0.046, 205 F2 for La2Ni1.67(1)Cd; α = 752.93(7), c = 380.95(6) pm, wR2 = 0.061, 260 F2 for Pr2Ni2Cd; α = 750.88(9), c = 378.33(7) pm, wR2 = 0.051, 195 F2 for Nd2Ni2Cd; α = 743.6(1), c = 374.0(1) pm, wR2 = 0.036, 386 F2 for Sm2Ni1.93(1)Cd; α = 734.9(1), c = 366.1(2) pm, wR2 = 0.030, 252 F2 for Dy2Ni1.94(1)Cd, with 13(12) variables per refinement. The 4g nickel site is only fully occupied in the neodymium and the praseodymium compound. Both modifications can be considered as intergrowths of distorted AlB2 and CsCl related slabs. In both modification the nickel and cadmium atoms build up two-dimensional [Ni2Cd] networks. In the low-temperature modifications the nickel atoms form pairs, while nickel zig-zag chains occur in the high-temperature modifications. These nickel fragments are condensed via the cadmium atoms. The crystal chemistry and the chemical bonding in these intermetallics is discussed

Development of Refractory and Rare Earth Metal Borides & Carbides for High Temperature Applications

2016 ◽  
Vol 3 (9) ◽  
pp. 3104-3113 ◽  
Author(s):  
T. S. R. Ch. Murthy ◽  
J. K. Sonber ◽  
K. Sairam ◽  
R.D. Bedse ◽  
J.K. Chakarvartty
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Metal Borides ◽  
Temperature Applications

Die Selten-Erd-Metall(III)-Fluorid-Oxoselenate(IV) MF[SeO3] (M = Y, Ho–Lu) imYF[SeO3]-Typ/ The Rare-Earth Metal(III) Fluoride Oxoselenates(IV) MF[SeO3] (M = Y, Ho–Lu) with YF[SeO3]-type Structure

2009 ◽  
Vol 64 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Christian Lipp ◽  
Thomas Schleid
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Rare Earth Metal ◽  
Room Temperature ◽  
Earth Metal ◽  
Selenium Dioxide ◽  
Molar Ratios ◽  
Triclinic Structure ◽  
Fluxing Agent ◽  
The Rare Earth

YF[SeO3]-type rare-earth metal(III) fluoride oxoselenates(IV) MF[SeO3] (M = Y, Ho-Lu) crystallize monoclinically in space group P21/c (no. 14) with Z = 4. Obeying the lanthanoid contraction, the lattice parameters decrease successively from a = 657.65(7), b = 689.71(7), c = 717.28(7) pm and β = 99.036(5)° for YF[SeO3] at 298 K to a = 648.39(6), b = 681.28(7), c = 705.81(7) pm and β = 98.657(5)° for LuF[SeO3] at 100 K (LT-LuF[SeO3], LT ≡ Low Temperature). The M3+ cations are occupying the general site 4e. Contrary to the triclinic structure of RT-LuF[SeO3] (RT ≡ Room Temperature; CN(Lu3+) = 7) the higher coordination number eight is achieved for the M3+ cations in all YF[SeO3]-type compounds. This results in [MO6F2]11− polyhedra (d(M-O) = 228 - 243/225 - 239 plus 263/258 pm, d(M-F) = 219/216 pm, M = Y/Lu), which are connected via common O・ ・ ・O edges to form infinite chains 1∞{[MOe 4/2Ot 2/1Ft 2/1]7−} (e ≡ edge-sharing, t ≡ terminal) running along [010]. Neighboring chains share common O3・ ・ ・O3 and O3・ ・ ・F edges generating 2∞{[M(O3)3/3(O2)2/2(O1)1/1F2/2]4−} sheets parallel to the (100) plane. Finally, these 2 ∞{[MO3F]4−} sheets are interconnected by Se4+ cations, which appear in isolated ψ1-tetrahedral [SeO3]2− anions (d(Se-O) = 167 - 175 pm). For the synthesis of the YF[SeO3]-type rare-earth metal(III) fluoride oxoselenates( IV) MF[SeO3] (M = Y, Ho-Lu), the rare-earth metal sesquioxides (M2O3) and trifluorides (MF3), and selenium dioxide (SeO2) in molar ratios of 1 : 1 : 3 with the fluxing agent CsBr were reacted within five days at 700 - 750 °C in evacuated graphitized silica ampoules.

scholarly journals Mild hydrothermally treated brewer's spent grain for efficient removal of uranyl and rare earth metal ions

RSC Advances ◽  
2020 ◽  
Vol 10 (73) ◽  
pp. 45116-45129
Author(s):  
Yi Su ◽  
Wendelin Böhm ◽  
Marco Wenzel ◽  
Silvia Paasch ◽  
Margret Acker ◽  
...  
Keyword(s):  
Rare Earth ◽  
Energy Consumption ◽  
Low Temperature ◽  
Environmental Impact ◽  
Hydrothermal Treatment ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Efficient Removal ◽  
Brewer’S Spent Grain ◽  
Spent Grain

Effective biosorbent ABSG is obtained via hydrothermal treatment of BSG at low temperature without activation, minimizing energy consumption and environmental impact.

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