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a -B 12 (rhombohedral, simple structure) b -boron (rhombohedral, complex structure, disordered)

The many phases of boron. a -B 12 (rhombohedral, simple structure) b -boron (rhombohedral, complex structure, disordered) g -B 28 (orthorhombic, high pressure modification). a -B 12. Unit Cell 4.9179 4.9179 12.5805 90 90 120 Vol 263.5 Z 3 Space Group R -3 m H

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a -B 12 (rhombohedral, simple structure) b -boron (rhombohedral, complex structure, disordered)

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  1. The many phases of boron a-B12 (rhombohedral, simple structure) b-boron (rhombohedral, complex structure, disordered) g-B28 (orthorhombic, high pressure modification)

  2. a-B12 Unit Cell 4.9179 4.9179 12.5805 90 90 120 Vol 263.5 Z 3 Space Group R -3 m H SG Number 166 Cryst Sys trigonal/rhombohedral Pearson hR12 Atom # OX SITE x y z SOF B 1 +0 18 h 0.11886(1) 0.88114(1) 0.89133(1) 1. B 2 +0 18 h 0.19686(1) 0.80314(1) 0.02432(1) 1.

  3. a-B12 G. Will et al. (2001)

  4. b-Boron Unit Cell 10.932(2) 10.932(2) 23.819(5) 90. 90. 120. Vol 2465.21 Z 321 Space Group R -3 m H SG Number 166 Cryst Sys trigonal/rhombohedral Pearson hR107 Atom # OX SITE x y z SOF B 1 +0 36 i 0.1730(1) 0.1741(1) 0.1767(1) 1. B 2 +0 36 i 0.3191(1) 0.2957(1) 0.1294(1) 1. B 3 +0 36 i 0.2614(1) 0.2175(1) 0.4197(1) 1. B 4 +0 36 i 0.2349(1) 0.2516(1) 0.3469(1) 1. B 5 +0 18 h 0.0545(1) 0.1090(2) 0.9437(1) 1. B 6 +0 18 h 0.0865(1) 0.1730(2) 0.0132(1) 1. B 7 +0 18 h 0.1098(1) 0.2196(2) 0.8860(1) 1. B 8 +0 18 h 0.1705(1) 0.3410(2) 0.0280(1) 1. B 9 +0 18 h 0.1287(1) 0.2574(2) 0.7666(1) 1. B 10 +0 18 h 0.1020(1) 0.2040(2) 0.6985(1) 1. B 11 +0 18 h 0.0564(1) 0.1128(2) 0.3266(1) 1. B 12 +0 18 h 0.0897(1) 0.1794(2) 0.3990(1) 1. B 13 +0 18 h 0.0579(1) 0.1158(2) 0.5538(1) 0.745(6) B 14 +0 6 c 0 0 0.3855(1) 1. B 15 +0 3 b 0 0 0.5 1. B 16 +0 18 h 0.0546(2) 0.1092(4) 0.1176(1) 0.272(7) B 17 +0 18 h 0.0833(14) 0.1666(28) 0.4760(11) 0.085(9) B 18 +0 18 h 0.1440(7) 0.2880(14) 0.5239(5) 0.066(6) B 19 +0 18 h 0.1805(7) 0.3610(14) 0.5347(5) 0.068(6) B 20 +0 36 i 0.2067(21) 0.2280(22) 0.0711(8) 0.037(4)

  5. b-Boron B84 entity: 3 shells B12 + B12 + B60

  6. Another shell of B60: direct fusion with neighboring balls (6) or via linkers (6)

  7. B21 linker unit

  8. 84 + 21 = 105 atoms (315 for hexagonal cell). On top of this: disorder.

  9. hR105 framework, band gap above EF (at 320 e) Disorder adds another 1.7 boron atoms (=5 electrons) compare b-Zn4Sb3 Zn6Sb5 framework, band gap above EF (at 38 e)

  10. g-B28

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