scholarly journals Trigonal Prismatic Coordination of Discrete Rare Earth Ions, Enforced by the Polyoxotungstate [P4W27O99(H2O)]16–

2021 ◽  
Author(s):  
Tuba Iftikhar ◽  
Natalya V. Izarova ◽  
Jan van Leusen ◽  
Paul Kögerler
Keyword(s):  
Rare Earth ◽  
Rare Earth Ions ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic

Ternary Thallides REMgTl (Re = Y, La – Nd, Sm, Gd – Tm, Lu)

2005 ◽  
Vol 60 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Rainer Kraft ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Rare Earth Metal ◽  
High Frequency ◽  
Three Dimensional ◽  
Earth Metal ◽  
X Ray ◽  
Sample Chamber ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic

The rare earth metal (RE)-magnesium-thallides REMgTl (RE = Y, La-Nd, Sm, Gd-Tm, Lu) were prepared from the elements in sealed tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. The thallides were characterized through their X-ray powder patterns. They crystallize with the hexagonal ZrNiAl type structure, space group P62m, with three formula units per cell. Four structures were refined from X-ray single crystal diffractometer data: α = 750.5(1), c = 459.85(8) pm, wR2 = 0.0491, 364 F2 values, 14 variables for YMgTl; α = 781.3(1), c = 477.84(8) pm, wR2 = 0.0640, BASF = 0.09(2), 425 F2 values, 15 variables for LaMgTl; α = 774.1(1), c = 473.75(7) pm, wR2 = 0.0405, 295 F2 values, 14 variables for CeMgTl; a = 760.3(1), c = 465.93(8) pm, wR2 = 0.0262, 287 F2 values, 14 variables for SmMgTl. The PrMgTl, NdMgTl, GdMgTl, TbMgTl, and DyMgTl structures have been analyzed using the Rietveld technique. The REMgTl structures contain two cystallographically independent thallium sites, both with tri-capped trigonal prismatic coordination: Tl1Mg3RE6 and Tl2Mg6RE3. Together the magnesium and thallium atoms form three-dimensional [MgTl] networks with Mg-Mg distances of 327 and Mg-Tl distances in the range 299 - 303 pm (data for CeMgTl)

Ternary Gallides REMgGa (RE = Y, La, Pr, Nd, Sm–Tm, Lu) – Synthesis and Crystal Chemistry

2003 ◽  
Vol 58 (9) ◽  
pp. 827-831 ◽  
Author(s):  
Rainer Kraft ◽  
Martin Valldor ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Cell Volume ◽  
Coordination Number ◽  
High Frequency ◽  
Three Dimensional ◽  
Gallium Atom ◽  
X Ray ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic

The title compounds have been synthesized by reacting the elements in sealed niobium or tantalum tubes in a high-frequency furnace. They crystallize with the hexagonal ZrNiAl type structure, space group P62m. All gallides have been characterized through their X-ray powder diffractogram. The cell volume decreases from the lanthanum to the lutetium compound as expected from the lanthanoid contraction. The structures of LaMgGa, PrMgGa, NdMgGa, SmMgGa and TmMgGa have been refined from single crystal diffractometer data. The structures contain two crystallographically independent gallium sites which both have a trigonal prismatic coordination: Ga1 by six RE and Ga2 by six Mg atoms. These trigonal prisms are capped on the rectangular sites by three Mg (RE) atoms, leading to coordination number 9 for each gallium atom. Together, the gallium and magnesium atoms form a three-dimensional [MgGa] network in which the rare earth atoms fill distorted hexagonal channels. Within the network the magnesium atoms have short Mg-Mg contacts, i. e. 312 pm in SmMgGa. The Mg-Ga distances in that gallide range from 284 to 287 pm. Bonding in the network is thus governed by strong Mg-Ga and Mg-Mg bonding. EuMgGa crystallizes with the orthorhombic TiNiSi type: Pnma, a = 783.1(2), b = 472.8(1), c = 829.8(2) pm.

The rare earth metal hydride tellurides REHTe (RE=Y, La–Nd, Gd–Er)

2019 ◽  
Vol 74 (6) ◽  
pp. 513-518
Author(s):  
Matthias Folchnandt ◽  
Daniel Rudolph ◽  
Jean-Louis Hoslauer ◽  
Thomas Schleid
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Rare Earth Metal ◽  
Metal Hydride ◽  
Earth Metal ◽  
Cesium Chloride ◽  
Coordination Pattern ◽  
Trigonal Prismatic Coordination ◽  
Type Crystal ◽  
Trigonal Prismatic

AbstractThe synthesis and crystal structure of a series of rare earth metal hydride tellurides with the composition REHTe (RE = Y, La–Nd, Gd–Er) is reported. These compounds have been obtained by the reaction of rare earth metal dihydrides (REH2) with elemental tellurium in sealed tantalum capsules at T = 700°C using cesium chloride (CsCl) as fluxing agent, which can be washed away with water due to the astonishing insensitivity of these hydride tellurides (REHTe) against hydrolysis. All of the compounds crystallize in the hexagonal space group P6̅m2 with a filled WC-type crystal structure, exhibiting a mutual trigonal-prismatic coordination of the heavy ions (RE3+ and Te2−), while the hydride anions reside in the trigonal prismatic voids surrounded by three rare earth metal cations expanding their coordination pattern to a tricapped trigonal prism. This 1H-type crystal structure is compared with the 1H- and 2H-type structures of the respective hydride selenides (REHSe, RE = Y, La–Nd, Gd–Tm, Lu). Both hexagonal basic crystal structures can be derived from the AlB2-type structure as demonstrated in a Bärnighausen tree by group-subgroup relationships.

scholarly journals Crystal structure of K3EuSi2O7

2021 ◽  
pp. 26-26
Author(s):  
Sabina Kovac ◽  
Predrag Dabic ◽  
Aleksandar Kremenovic
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
X Ray Diffraction ◽  
Coordination Environment ◽  
Distorted Octahedral ◽  
Earth Cation ◽  
Trigonal Prismatic Coordination ◽  
Trigonal Prismatic ◽  
The Eu

As a part of the research of the flux technique for growing alkali rare-earth elements (REE) containing silicates, tripotassium europium disilicate, K3EuSi2O7, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in the space group P63/mcm. In the crystal structure of the title compound, one part of the Eu cations are in a slightly distorted octahedral coordination and the other part are in an ideal trigonal prismatic coordination environment. The disilicate Si2O7 groups connect four EuO6 octahedra and one EuO6 trigonal prism. Three differently coordinated potassium cations are located between them. Silicates containing the larger rare earth elements usually crystallize in a structure that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment.

scholarly journals Structure, Chemical Bonding and 119Sn Mössbauer Spectroscopy of LaRhSn and CeRhSn

2005 ◽  
Vol 60 (10) ◽  
pp. 1036-1042 ◽  
Author(s):  
Tobias Schmidt ◽  
Dirk Johrendt ◽  
C. Peter Sebastian ◽  
Rainer Pöttgen ◽  
Kazimierz Łątka ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Frequency ◽  
Three Dimensional ◽  
Strong Mixing ◽  
X Ray ◽  
Band Structure Calculations ◽  
Trigonal Prismatic Coordination ◽  
Structure Calculations ◽  
Trigonal Prismatic ◽  
The Rare Earth

The rare earth (RE) stannides LaRhSn and CeRhSn were prepared from the elements by arcmelting or by reactions in sealed tantalum tubes in a high-frequency furnace. The structures have been refined from X-ray single crystal diffractometer data: ZrNiAl type, P6̅2̅m, a = 748.74(5), c = 422.16(3) pm, wR2 = 0.0307, 310 F2 values for LaRhSn and a = 745.8(1), c = 408.62(9) pm, wR2 = 0.0397, 354 F2 values for CeRhSn with 14 variables per refinement. The structures contain two crystallographically different rhodium sites which both have a tricapped trigonal prismatic coordination: [Rh1Sn3RE6] and [Rh2Sn6RE3]. Together the rhodium and tin atoms (280 - 288 pm Rh-Sn distances in LaRhSn and 277 - 285 pm in CeRhSn) build up three-dimensional [RhSn] networks in which the rare earth atoms fill distorted hexagonal channels. DFT band structure calculations reveal a large cerium 4 f contribution at the Fermi level and a strong mixing of cerium 5d/4 f with rhodium 4d orbitals. These results are in agreement with the short Ce-Rh bonds (304 and 309 pm) and also with the electronic and magnetic properties. 119Sn Mössbauer spectra of LaRhSn and CeRhSn show a single tin site at isomer shifts of δ = 1.98(2) (LaRhSn) and 1.79(1) mm/s (CeRhSn) subject to quadrupole splitting of Δ EQ = 0.79(4) (LaRhSn) and 1.12(3) mm/s (CeRhSn). The 1.8 K data show no transferred hyperfine field at the tin site for CeRhSn.

La3Cl3BC – Structure, Bonding and Electrical Conductivity

2005 ◽  
Vol 60 (5) ◽  
pp. 499-504 ◽  
Author(s):  
Hui-Yi Zeng ◽  
Hiroki Okudera ◽  
Chong Zheng ◽  
Hansjürgen Mattausch ◽  
Reinhard K. Kremer ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Rare Earth ◽  
Monoclinic System ◽  
Space Group ◽  
Valence Electrons ◽  
Trigonal Prismatic Coordination ◽  
Cl Atoms ◽  
Polymeric Anion ◽  
Trigonal Prismatic ◽  
Trigonal Prisms

A new rare earth carbide boride halide, La3Cl3BC, has been prepared by heating a mixture of stoichiometric quantities of LaCl3, La, B and C at 1050 °C for 10 days. La3Cl3BC (La3Br3BC type) crystallizes in the monoclinic system with space group P21/m (No. 11), a = 8.2040(16), b = 3.8824(8), c=11.328(2)Å , β =100.82(3)°. In the structure, monocapped trigonal prisms containing B-C units are condensed into chains along the b direction, and the chains are further linked by Cl atoms in the a and c directions. The condensation results in a polymeric anion 1∞[BC] with a spine of B atoms in a trigonal prismatic coordination by La, and the C atoms attached in a square pyramidal coordination. The B-B and B-C distances are 2.16 and 1.63 Å , respectively. La3Cl3BC is metallic. The EH calculation shows that the distribution of valence electrons can be formulated as (La3+)3(Cl−)3(BC)5− · e−.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Rare Earth Ions ◽  
Ion Concentration ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Combustion Technique

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

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