Solid phase
Official name
alpha-Bismuth trioxide
Secondary names
alpha-Bismuth(III) oxide; alpha-Bismuth sesquioxide; Bi2O3
CAS number
1304-76-3
Type
Family
covalent network solid
Class
sheet covalent network solid
Compound type
oxide
Structure of alpha-$Bi_2O_3$ (room temperature phase); red atoms are oxygens; Malmros 1970
Chemical composition
Formula
$Bi_2O_3$
Chemical formula
Bi2O3
Elemental formula
Bi2 O3
Isotope mixture type
terrestrial abundance
10.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$Bi$ Bismuth element 2 0.4 1 constituent element main
$O$ Oxygen element 3 0.6 1 constituent element main
Chemical bonds
  Bond Number
$ >Bi-O-$ 6
Class
sheet covalent networks (10)
Type
one metal and one non-metal atoms sheet networks (10.04)
Equivalent mineral
Bismite
Phase name
alpha-Bi2O3
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
P2(1)/c
Molar mass
465.958 $g/mol$
Density
8.90 $g/cm^3$
State NTP
solid
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid to delta-Bi2O3 > 729°C (> 1002K)
solid-solid from beta-Bi2O3 < 303°C (< 576K)
solid-solid from gamma-Bi2O3 < 500°C (< 773K)
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.180
Refraction index $n_{\alpha}$
2.00
Refraction index $n_{\beta}$
1.82
Pure color
yellow
Color
yellow
Diaphaneity
transparent to translucent
Luster
adamantine
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