Ein Beitrag zur Strukturchemie der Selten‐Erd‐Trifluoride

Greis, O.; Petzel, T.

doi:10.1002/zaac.19744030102

Cited by 116 publications

(43 citation statements)

References 18 publications

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“…(27) for the relative lattice energy of non-cubic LnF3, in which the cubic root of the X-ray volume per formula unit is regarded as a possible substitute for the lattice parameter of ao in (27). Greis and Petzel (1974), however, showed that the lattice parameters of orthorhombic LnF3 change anomalously at ErF3. A possible change of the coordination polyhedron from a tricapped trigonal prism (SmF3-ErF3) to a bicapped one (TmF3-LuF3) or from a bicapped,trigonal prism (SmF3-ErF3) to a distorted square antiprism (TmF3-LuF3) have also been discussed (Greis and Haschke, 1982).…”

Section: Screening Constant and A New Rspet Formulationmentioning

confidence: 93%

“…The cubic root of the X-ray volume per formula unit of LnF3 has been calculated from the lattice parameters in Greis and Petzel (1974). For SmF3 and EuF3, ex perimental lattice constants of both the hex agonal and orthrhombic polymorphs have been previously reported (Greis and.…”

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

“…This correction eliminates a systematic difference (LnF3) values derived by the thermodynamic data for the hydrated trifluorides given in Greis and Haschke (1982). All the values for the cubic root of X-ray volume per formula unit are after Greis and Petzel (1974). The regression line for the hexagonal series is determined by the data points for Ce-Eu shown by the filled circles and open triangles.…”

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

“…This requires an evaluation of (i) the standard enthalpy of forma tion for the hypothetical orthorhombic LnF3 with Ln=La, Ce, Pr and Nd, and (ii) the effect of a structural change within the last three members of orthorhombic series upon their stan dard enthalpies of formation. For the standard enthalpy of formation, we evaluate the value of A Hf (LnF3i hex) -A Hf (LnF3, rhm) for La, Ce, Pr, and Nd in the following way: Greis and Petzel (1974) reported experimental lattice parameters of SmF3 and EuF3 with hexagonal and orthorhombic structures; these experimental data have been combined with the linear correla tions between U*(LnF3) and 1 / a for both struc tural series (Fig. 5).…”

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

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Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theory

1992

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The refined spin-pairing energy theory (RSPET) has been improved in order to understand quan titatively the tetrad or double-double effects recognized in the Ln3+ ionic radii. Since the ionic radii have been determined from the lattice constants and structural parameters of Ln01.5 and LnF3, the lattice energies of the compounds and the enthalpy difference of d Hf (LnF3)-A Hf (LnO1,5) have been exam ined by the improved RSPET. The RSPET parameters for the lowest levels of 4fq electronic configura tions strongly depend upon the effective nuclear charge (Z*). Such effects due to Z* have been taken into account. This made it possible to separate the variations in the lattice energies and the enthalpy difference across the Ln3+ series into the following two parts: (1) the large variation as a smooth func tion of q (the lanthanide contraction trend), and (2) the small zig-zag variation referred to the tetrad or double-double effect. The lattice energy of Ln01.5 and A Hf (LnF3)-A Hf (Ln01.5) exhibit upward con cave tetrad curves in their plots against q of Ln3+. The tetrad effect in the lattice energy of LnF3 is less conspicuous. This means that the Racah parameters for Ln3+ decrease very slightly in going from the gaseous free Ln3+ to LnF3, and then decrease greatly to Ln01.5, in accordance with the nephelauxetic series. The differences in Racah parameters between LnF3 and Ln01,5 have been estimated from A Hf(LnF3) -A Hf(Ln01.5) by means of an inversion technique based on the improved RSPET. The RSPET results for the thermochemical data are consistent with the careful spectroscopic determinations of Racah parameters for NdF3 and Nd01.5. Both the tetrad effect and the smooth lanthanide contraction seen in the Ln3+ ionic radii can be interpreted in terms of the quantum mechanical energetics of 4f elec trons.

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Section: Screening Constant and A New Rspet Formulationmentioning

confidence: 93%

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

Section: Thermochemical Properties Of Ln Trifluoridesmentioning

confidence: 99%

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Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theory

1992

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“…11,12 This demonstrates that phase modification can be considered as an alternative to regulate the functional properties of inorganic materials. [15][16][17][18] An increase in the repulsive energy between fluoride ions with a decrease in the ionic radius of the lanthanide induced a phase transition from hexagonal to orthorhombic. 14 The RE 3+ ions have a coordination number of 11 in the hexagonal structure and 9 in the orthorhombic.…”

Section: Introductionmentioning

confidence: 99%

Doping alkaline-earth: a strategy of stabilizing hexagonal GdF3 at room temperature

et al. 2013

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Hexagonal GdF3 is a more efficient phosphor host compared with the traditional orthorhombic form but the hexagonal phase is thermodynamically unstable at room temperature. Herein, we present a strategy to stabilize hexagonal GdF3 by doping with alkaline-earth ions in a mild hydrothermal reaction system. The selection of the dopant, effect of the dopant amount and the mechanism of the phase transition was discussed in detail. The luminescence variation of GdF3:Eu was demonstrated to verify the phase transformation. Furthermore, the upconversion luminescence of the Sr-doped and undoped GdF3:Yb/Er was investigated.

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Zwei Fluoridborate des Gadoliniums: Gd2F3[BO3] und Gd3F3[BO3]2

Müller‐Bunz

Schleid

2002

Z. anorg. allg. Chem.

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Inhaltsübersicht. Durch flußmittelunterstützte Festkörperreaktion von Gd 2 O 3 und GdF 3 mit B 2 O 3 (Flußmittel: CsCl, molares Verhältnis: 1 : 1 : 1 : 6, verschweißte Tantalampulle, 700°C, 7 d) läßt sich das neue Gadoliniumfluoridborat Gd 2 F 3 [BO 3 ] (monoklin, P2 1 /c; a ϭ 1637,2(1), b ϭ 624,78(4), c ϭ 838,04(6) pm, β ϭ 93,341(8)°; V m ϭ 64,418(6) cm 3 /mol, Z ϭ 8) in Form farbloser, flächenreicher Prismen einkristallin erhalten. Die vier kristallographisch verschiedenen Gd 3ϩ -Kationen werden darin allesamt überkappt quadratisch-antiprismatisch (CN ϭ 9) von Fluorid-und Oxid-Anionen umgeben, wobei letztere immer Bestandteil isolierter, trigonal planarer [BO 3 ] 3Ϫ -Anionen sind. Die sechs kristallographisch unabhängigen F Ϫ -Anionen liegen allesamt in mehr oder we-Abstract. By flux-supported solid-state reaction of Gd 2 O 3 and GdF 3 with B 2 O 3 (flux: CsCl, molar ratio: 1 : 1 : 1 : 6, sealed tantalum capsule, 700°C, 7 d) the new gadolinium fluoride borate Gd 2 F 3 [BO 3 ] (monoclinic, P2 1 /c; a ϭ 1637.2(1), b ϭ 624.78(4), c ϭ 838.04(6) pm, β ϭ 93.341(8)°; V m ϭ 64.418(6) cm 3 /mol, Z ϭ 8) was obtained as colourless, prismatic, face-rich single crystals. The four crystallographically different Gd 3ϩ cations (CN ϭ 9) are all capped square-antiprismatically surrounded by fluoride and oxide anions, in which the latter represent always components of isolated trigonal planar [BO 3 ] 3Ϫ anions. The six crystallographically independent F Ϫ anions all reside in more or less planar coordination of three Gd 3ϩ cations. Thus the constitution of Gd 2 F 3 [BO 3 ] can be described as Einleitung Während die Zweistoffsysteme B 2 O 3 / M 2 O 3 (M ϭ Sc, Y, La; Ce Ϫ Lu) bereits ausführlich untersucht wurden [1Ϫ4], ist über anionisch derivatisierte Oxoborate der dreiwertigen Selten-Erd-Elemente fast nichts bekannt. Sieke [5] (und in Fortsetzung davon Nikelski [6]) beschreiben zwar den Einbau von Chlorid-Anionen in Lanthanidborate, so daß mit der Kenntnis um die Zusammensetzung und den strukturellen Aufbau von Ce 3 Cl 3 [BO 3 ] [7], PrCl(BO 2 ) 2 [8] und Er 2 Cl 2 [B 2 O 5 ] [9] wenigstens auf diesem Gebiet ein gewisser

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Ein Beitrag zur Strukturchemie der Selten‐Erd‐Trifluoride

Cited by 116 publications

References 18 publications

Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theory

Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theory

Doping alkaline-earth: a strategy of stabilizing hexagonal GdF3 at room temperature

Zwei Fluoridborate des Gadoliniums: Gd2F3[BO3] und Gd3F3[BO3]2

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