scholarly journals Rare-earth atom motions inROs4Sb12(R= La, Pr, Nd, Sm)

2010 ◽  
Vol 200 (1) ◽  
pp. 012213 ◽  
Author(s):  
S Tsutsui ◽  
H Uchiyama ◽  
J P Sutter ◽  
A Q R Baron ◽  
H Sugawara ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Atom

Structure and stereochemistry in 'f-block' complexes of high coordination number. VIII. The [M(unidentate)9] system. Crystal structures of [M(OH2)9] [CF3SO3]3, M = La, Gd, Lu, Y

1983 ◽  
Vol 36 (3) ◽  
pp. 483 ◽  
Author(s):  
JM Harrowfield ◽  
DL Kepert ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Rare Earth ◽  
Crystal Structures ◽  
Ethyl Sulfate ◽  
Rare Earth Atom ◽  
Repulsion Energy ◽  
High Coordination Number ◽  
Tricapped Trigonal Prism ◽  
Cell Dimensions ◽  
High Coordination ◽  
The Rare Earth

The crystal structures of the nonahydrates of the rare earth trifluoromethanesulfonates, [M(OH2)9] [CF3SO3]3 have been determined at 295 K for the configurations fO, f7, f14, i.e. M = La, Gd, Lu, together with that of the yttrium analogue. The structures are similar to those of the rare earth ethyl sulfate nonahydrates, belonging to space group P6,/m (hexagonal) with cell dimensions a ≈ 13.7, c ≈ 7.5 �, Z 2, with the coordination about the rare earth atom being a tricapped trigonal prism. The structure is compared with that found from repulsion energy calculations.

Structure of Rare-earth/Alkali Halide Complexes

2001 ◽  
Vol 56 (11) ◽  
pp. 721-724 ◽  
Author(s):  
Z. Akdeniz ◽  
Z. Çiçek Önem ◽  
M. P. Tosia
Keyword(s):  
Rare Earth ◽  
Alkali Halide ◽  
Elevated Temperatures ◽  
Alkali Halides ◽  
Energy Difference ◽  
Alkali Atom ◽  
Complexing Agent ◽  
Coordination State ◽  
Rare Earth Atom ◽  
The Rare Earth

Abstract Vapour complex formation of rare-earth halides with alkali halides strongly increases the volatility of these compounds. We evaluate the structure taken by such complexes having the chemical formulas MRX4, M2RX5 and M3RX6, where X = F or Cl and typically M = Li or Na and R = La. The roles played by the two types of metal atom is investigated in MRX4 complexes by also taking M = K, Rb or Cs and R = Gd or Lu. The main predictions that emerge from our calculations are as follows: (i) in MRX4 a fourfold coordination of the rare-earth atom is accompanied by twofold or threefold coordination of the alkali atom, the energy difference in favour of the twofold-coordination state being about 0.3 eV in the case of the LiF complexing agent but even changing sign as the ionic radius of either the alkali or the halogen is increased; (ii) in M2RX5 a fivefold coordination of the rare-earth atom is energetically more stable than a fourfold one, by again not more than about 0.3 eV; (iii) in M3RX6 the fivefold and sixfold coordinations of the rare-earth atom are energetically competitive; and (iv) in both M2RX5 and M3RX6 each coordination state can be realized in various forms that differ in detail but are close in energy. Bond fluctuations and disorder around the rare-earth atom can be expected to be a general feature at elevated temperatures, both in the vapour and in liquid rare-earth/alkali halide mixtures.

Electronic structures and magnetic properties of rare-earth-atom-doped BNNTs

2015 ◽  
Vol 11 (2) ◽  
Author(s):  
Juan Ren ◽  
Ning-Chao Zhang ◽  
Peng Wang ◽  
Chao Ning ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Electronic Structures ◽  
Rare Earth Atom

Ternary Rare Earth Transition Metal Zinc Compounds RT2Zn20 with T = Fe, Ru, Co, Rh, and Ni

1997 ◽  
Vol 52 (9) ◽  
pp. 1023-1030 ◽  
Author(s):  
Tono Nasch ◽  
Wolfgang Jeitschko ◽  
Ute Ch. Rodewald
Keyword(s):  
Rare Earth ◽  
Transition Metal ◽  
Metal Atom ◽  
Transition Metal Atom ◽  
Hexagonal Prism ◽  
Rare Earth Atom ◽  
Zinc Compounds ◽  
A Site ◽  
Cold Pressed ◽  
Zinc Site

Forty eight new compounds RT2Zn20 were prepared by annealing cold-pressed pellets of the elemental components in an argon atmosphere. They crystallize with the cubic CeCr2Al20 type structure (Fd3̅̅m , Z = 8), which was refined from single-crystal diffractometer data of TbFeiZn20 (a = 1411.1(1) pm ), YRu2Zn20 (a = 1422.6(1) pm ), DyRu2Zn20 (a = 1422.1(1) pm), GdCo2Zn20 (a = 1406.0(1) pm ), DyRh2Zn20 (a = 1418.2(1) pm ), and TmNi2Zn20 (a= 1401.6(1) pm) to conventional residuals varying betw een R = 0.011 and R - 0.024. The com pounds have a tendency for tw inning, thus m im icking hexagonal sym metry, with the cubic [111] axis as the axis w ith the pseudohexagonal symmetry. M inor inconsistencies in the cell volum es of these com pounds indicate slight deviations from the ideal com position. N evertheless, the five atom ic sites of this structure w ere found to be fully occupied w ithin the error lim its w ith the exception of one zinc site of TmNi2Zn20. The coordination for the site of the rare earth atom s is a Frank-K asper polyhedron with coordination num ber (CN) 16. The transition metal atom s occupy a site w ith icosahedral zinc coordination (CN 12). Two of the three zinc sites are in pentagonal prism atic coordination of zinc atom s, capped by rare earth and/or transition metal atom s (CN 12), w hile the third zinc site has 12 zinc neighbors form ing a hexagonal prism , w hich is capped by tw o rare earth atom s (CN 14).

Nonlinear optical and optical limiting properties of polymeric carboxyl phthalocyanine coordinated with rare earth atom

2017 ◽  
Vol 66 ◽  
pp. 98-105 ◽  
Author(s):  
Peng Zhao ◽  
Zonghua Wang ◽  
Jishi Chen ◽  
Yu Zhou ◽  
Fushi Zhang
Keyword(s):  
Rare Earth ◽  
Nonlinear Optical ◽  
Optical Limiting ◽  
Rare Earth Atom

How cerium filling fraction influences thermal factors and magnetism in CeyFe4-xNixSb12.

2000 ◽  
Vol 626 ◽  
Author(s):  
L. Chapon ◽  
D. Ravot ◽  
J.C. Tedenac ◽  
F. Bouree-Vigneron
Keyword(s):  
Thermal Conductivity ◽  
Rare Earth ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Theoretical Calculations ◽  
Filling Fraction ◽  
Rare Earth Atom ◽  
Filled Skutterudites ◽  
Order Of Magnitude ◽  
Mass Fluctuation

Since few years, cerium filled and partially filled skutterudites are intensively studied because they show a wide variety of fundamental and applied properties. One of them consists in high values of thermal factors for rare earth atom in antimony skutterudites [1,2]. Slack suggests [3,4] a incoherent rattling of this ion in the oversized cage “Sb12” surrounding the cerium which affects highly the phonon motion and thus lowers the lattice thermal conductivity (kl). As a rule, the lattice thermal conductivity is decreased by a factor of 5 or greater by filling entirely the voids of the binary filled skutterudites with rare earth atoms [5]. Besides, kl decreases for partially filled compounds in respect with totally filled ones [6,7]. Mass fluctuation mechanism between cerium atom and vacancy is obviously involved as the origin of this last reduction. On that purpose, theoretical calculations [7] demonstrate that the reduction belonging to mass fluctuation mechanism is an order of magnitude lower than the measured decrease. As the mass fluctuation added to the “rattling” on the cerium site is not sufficient to explain such low values of thermal conductivity, another phonon scattering mechanism must exist. In order to find another mechanism we present the influence of the filling fraction of cerium on thermal factors and the temperature dependence of this factor for a partially filled compound.

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