Crystallographic investigation of the Co–B–O system

• Published in: Journal of solid state chemistry Vol. 174; no. 1; pp. 189 - 197
• Main Authors: Rowsell, J.L.C., Taylor, N.J., Nazar, L.F.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01-08-2003; Elsevier
• Subjects: Cobalt; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Inorganic compounds; Magnetic frustration; Metal borates; Physics; Salts; Single crystal X-ray diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Single crystal X-ray diffraction; Metal borates; Cobalt; Magnetic frustration; Inorganic compounds; Transition element compounds; XRD; Experimental study; Cobalt Tetraborates; Monocrystals; Powder pattern; Cobalt Borates; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/S0022-4596(03)00217-2

The crystalline phases within the Co–B–O system have been investigated with a combination of powder and single crystal X-ray diffraction. By varying the synthetic conditions, four pure phases can be made by solid-state reaction: Co
3(BO
3)O
2, a homometallic ludwigite; Co
3(BO
3)
2, an orthoborate with the kotoite structure; Co
2(B
2O
5), a pyroborate; and the tetraborate Co(B
4O
7). Herein, we report the first structural refinement of the latter phase (orthorhombic, space group
Pbca,
a=8.1189(7)
Å,
b=8.621(1)
Å,
c=13.737(1)
Å,
V=961.5(2)
Å
3,
Z=8,
R
1=0.0319, w
R
2=0.0693 [
I>2
σ(
I)]). The pyroborate structure was also refined by single crystal methods in order to match the calculated powder diffraction pattern with the observed pattern (triclinic, space group
P
1
̄
,
a=3.1689(3)
Å,
b=6.1530(5)
Å,
c=9.2734(7)
Å,
α=104.253(4)°,
β=90.821(4)°,
γ=92.098(5)°,
V=175.08(3)
Å
3,
Z=2,
R
1=0.0159, w
R
2=0.0366 [
I>2
σ(
I)]). Flux growth of Co(B
4O
7) also yielded single crystals of the new compound Co
4(BO
2)
6O (cubic, space group
I
4
̄
3m
,
a=7.4825(3)
Å,
V=418.93(3)
Å
3,
Z=2,
R
1=0.0176, w
R
2=0.0373 [
I>2
σ(
I)]).