Zur Kristallstruktur von Cu₂M(BO₃)O₂ (M = Fe³⁺, Ga³⁺)

Abstract

Aus einer B2O3‐Schmelze gelang die Synthese von Einkristallen der Substanzen Cu2M(BO3)O2 (M = Fe3+ (I), Ga3+ (II)), die isotyp zueinander sind und in einer monoklin verzerrten Strukturvariante eines Ludwigites mit teilweise geordneter Metallverteilung kristallisieren. Röntgenographische Untersuchungen an Einkristallen ergeben die Raumgruppe C 2h5–P 21/c (Nr. 14) mit I: a = 3,108(1); b = 12,003(1); c = 9,459(3) Å; b̃ = 96,66(3)°; Z = 4 und II: a = 3,1146(2); b = 11,921(3); c = 9,477(2) Å; b̃ = 97,91(2)°; Z = 4. Die Metallkationen sind verzerrt oktaedrisch von Sauerstoffionen koordiniert. Die Struktur weist sowohl isolierte, planare BO3‐Baugruppen als auch nicht an Bor gebundenen Sauerstoff auf.

Destruction of long-range magnetic order in an external magnetic field and the associated spin dynamics in Cu2GaBO5 and Cu2AlBO

“…In the present paper, we report the results of magnetic measurements on the two copper ludwigites Cu 2 GaBO 5 and Cu 2 AlBO 5 that share the crystal structure depicted in Fig. 1, according to the available x-ray structure refinement [11,12] and our own refinement based on the results of singlecrystal x-ray diffraction. The unit cell is monoclinic, described by the space group P2 1 /c with the lattice parameters a [11] or Al [12].…”

“…1, according to the available x-ray structure refinement [11,12] and our own refinement based on the results of singlecrystal x-ray diffraction. The unit cell is monoclinic, described by the space group P2 1 /c with the lattice parameters a [11] or Al [12]. The magnetic Cu 2+ ions occupy four inequivalent positions in distorted octahedral coordinations, which form edge-sharing zigzag walls perpendicular to the b axis.…”

“…For the purposes of our study, which includes neutron scattering, we used isotopically enriched boric acid with 99.88 at.% 11 B isotope from Ceradyne, Inc. as a starting material to minimize neutron absorption by the 10 B isotope. The same isotope-enriched samples were also beneficial for 11 B nuclear magnetic resonance (NMR) measurements, whereas all other measurements presented here were performed on the same set of samples for consistency. We have investigated both Cu 2 GaBO 5 and Cu 2 AlBO 5 compounds using muon spin relaxation (μSR).…”

“…From the point of view of quantum magnetism, synthetic compounds where the divalent metal ion M is represented by magnetic Cu 2+ with S = 1/2 attract most attention. For simplicity, the trivalent metal ion M should preferably remain nonmagnetic (for instance, Al 3+ or Ga 3+ ) [11][12][13], although ludwigites with magnetic trivalent ions, e.g., M = Fe 3+ (S = 5/2), Mn 3+ (S = 2), or Cr 3+ (S = 3/2), are also well known [13][14][15][16][17]. In particular, some of them find practical applications as conversion-type electrode materials for lithium-ion batteries [17,18].…”

On the structural relations of malachite. I. The rosasite and ludwigite structure families

“…Several hettotypes of the ludwigite type have been reported in the literature. For example, the synthetic coppercontaining derivatives Cu 2 MO 2 BO 3 (M = Al, Ga, Fe; Hriljac et al, 1990;Schaefer & Bluhm, 1995) are representatives of a monoclinically distorted ludwigite type crystallizing in the space group P2 1 /a (No. 14), with the $ 12 Å axis as the monoclinic axis.…”