RE₄B₄O₁₁F₂ (RE = Eu, Dy): New Phases Isotypic to the Fluoride Borate Gd₄B₄O₁₁F₂

Abstract

The rare-earth fluoride borates RE 4 B 4 O 11 F 2 (RE = Eu, Dy) were synthesized in a Walkertype multianvil apparatus from the corresponding rare-earth oxides and fluorides, and boron oxide. Eu 4 B 4 O 11 F 2 was obtained under high-pressure/high-temperature conditions of 5 GPa and 900 • C, and Dy 4 B 4 O 11 F 2 at 8 GPa and 1000 • C. The single-crystal structure determinations revealed that both compounds are isotypic to Gd 4 B 4 O 11 F 2 , crystallizing in the space group C2/c (Z = 4) with the parameters a = 1368.2(3), b = 465.4(1), c = 1376.6(3) pm, β = 91.2(1) • , V = 0.8765(3) nm 3 , R 1 = 0.0232, and wR 2 = 0.0539 (all data) for Eu 4 B 4 O 11 F 2 and a = 1349.5(3), b = 460.9(1), c = 1362.5(3) pm, β = 91.3(1) • , V = 0.8472(3) nm 3 , R 1 = 0.0353, and wR 2 = 0.0729 (all data) for Dy 4 B 4 O 11 F 2 . These phases are entirely different from the recently discovered lanthanum fluoride borate La 4 B 4 O 11 F 2 , which exhibits the same constitution in another structure type with space group P2 1 /c.

RE4B4O11F2 (RE = Pr, Nd): Two New Rare-earth Fluoride Borates Isotypic to Gd4B4O11F2

“…As reported for the isotypic phases RE 4 B 4 O 11 F 2 (RE = Eu, Gd, Dy) [6,7], the new compounds RE 4 B 4 O 11 F 2 (RE = Pr, Nd) also form in a wide pressure and temperature range. In many syntheses with varying pressure and temperature conditions, the desired phases RE 4 B 4 O 11 F 2 (RE = Pr, Nd) were the main products, but contained small amounts of the corresponding high-pressure rare-earth metaborates γ-RE(BO 2 ) 3 (RE = Pr, Nd) [ has been attempted several times in our group using various reaction conditions, but without any success.…”

“…Here, we report about two new compounds RE 4 B 4 O 11 F 2 (RE = Pr, Nd) in this system, which are isotypic to RE 4 B 4 O 11 F 2 (RE = Eu, Gd, Dy) [6,7]. The syntheses and crystal structures of RE 4 B 4 O 11 F 2 (RE = Pr, Nd) are discussed in comparison to the isotypic compounds, and the IR spectra of both new compounds are presented.…”

“…For the chemical composition RE 4 B 4 O 11 F 2 , two different structure types were obtained by highpressure/high-temperature syntheses. In 2010, Haberer et al presented the compound La 4 B 4 O 11 F 2 [4] crystallizing in space group P2 1 /c with the lattice parameters a = 778.1 (2), b = 3573.3 (7), c = 765.7(2) pm, and β = 113.92(3) • (Z = 8). The crystal structure consists of BO 3 groups (∆) which are either isolated (∆), connected via common corners (∆∆), or connected via BO 4 tetrahedra forming the fundamental building block (FBB) 2∆ :∆ ∆ (after Burns et al [5]).…”

“…The structural motif consists of two BO 3 groups (∆) and two BO 4 tetrahedra ( ), and can be described with the fundamental building block 2∆2 :∆ ∆, which represented a novelty in borate chemistry. Later in 2010, Haberer [7].…”

High-pressure Syntheses and Characterization of the Rare Earth Borates RE5(BO3)2F9 (RE=Dy, Ho)

“…Up to now, high-temperature syntheses under ambient pressure conditions did not lead to any dysprosium or holmium fluoride borates. In the last years, a breakthrough was achieved in the system RE-B-O-F via high-pressure/high-temperature experiments leading to the compounds Dy 3 (BO 3 ) 2 F 3 [5], Dy 4 B 4 O 11 F 2 [6] and RE 2 (BO 3 )F 3 (RE = Dy, Ho) [7], which are built up exclusively of isolated trigonalplanar [BO 3 ] 3− groups. With the syntheses of the compounds RE 5 (BO 3 ) 2 F 9 (RE = Er -Yb) [8 -10], three new rare earth fluoride borates were added to the known RE-B-O-F phases.…”