NSM Archive - Boron Nitride (BN) - Basic Parameters and Lattice properties

BN - Boron Nitride

Boron nitride (BN) has at least four crystal modifications of BNw (wurtzite structure), BNcub (cubic BN, zinc blende structure), BNhex (hexagonal BN), and rhombehedral. The properties of the first three (more common) modifications are presented.
BNhex is stable under normal conditions. BNhex (Hexagonal, also known as a-BN) with the structure similar to graphite is known for more than a century. Many properties of hexagonal BN are highly anisotropic and depend on the growth method. In many cases, the different values of BNhex physical parameters given reflect the differences in material properties of hexagonal BN grown by different methods.
BNcub is metastable under normal conditions. BNcub (Zinc blende modification , also known as cubic or sphalerite or b-BN) was first synthesized in 1957 using the technique similar to that used for diamond growth. Now crystals with a few millimeter sizes are commercially available.
The BNw phase is metastable under all conditions. BNw (Wurtzite structure, also known as g-BN) was first synthesized in 1963. Typically, BN crystals with wurtzite symmetry are very small (fraction of microns), are highly defective, and contain other phases.

Basic Parameters for Zinc Blende crystal structure
Basic Parameters for Hexagonal crystal structure
Basic Parameters for Wurtzite crystal structure

Basic Parameters for Zinc Blende crystal structure

    Remarks Referens
Crystal structure Zinc Blende    
Group of symmetry T2d — F43m    
Number of atoms in 1 cm3    
Debye temperature 1700 K    
Density 3.4870 g cm-3
3.450 g cm-3
X-ray
Soma et al. (1974)
Rumyantsev et al. (2001)
Lattice constant, a 3.6157(10) A  X-ray Sohno et al. (1974)
Melting point, Tm 2973° C Wentorf (1957)
Bulk modulus 400 GPa 300 K  
Hardness 9.5 on the Mohs scale  
Surface hardness 4500 kg mm-2 300 K  
Second order elactic moduli, c11 7.120 ·1012 dyn cm-2 300 K, interpolated from
measured values of other
III-IV compound
Steigmeier (1963)
Phonon wevenumber vLO 1305(1) cm-1 300 K, Raman Sanjurjo et al. (1983)
Phonon wevenumber vTO 1054.7(6) cm-1 300 K, Raman Sanjurjo et al. (1983)
Brillouin zone of the face centered cubic lattice, the Bravais lattice of the diamond and zincblende structures.
    Remarks Referens
Energy gaps, Eg
6.1÷6.4 eV 300 K Rumyantsev et al. (2001)
Energy gaps, Egind
G15v-X1c
6.4(5) eV 300 K, UV absorption;
other data in range 6...8eV
Chrenko (1974)
  6.99 eV
8.6 eV
calculated, Band structure
calculated, Band structure
Huang & Ching (1985)
Prasad & Dubey (1984)
Energy gaps, Eg,dir
G15v-G1c
14.5 eV
10.86 eV
9.94 eV
300 K, reflecsivity
calculated, Band structure
calculated, Band structure
Philipp & Taft (1962)
Prasad & Dubey (1984)
Huang & Ching (1985)
Effective electron mass  ml 0.752 mo calculated from
band structure data
Huang & Ching (1985)
Effective electron mass
  (longitudinal) ml
    (transversal) mt
0.35mo
0.24mo
1.2mo
0.26mo
Xu & Ching et al. (1991)
Effective hole masses (heavy) mh 0.375 mo
0.962 mo
|| [100]
|| [111]
Madelung (1991)
Effective hole masses (heavy) mlp 0.150 mo
0.108 mo
|| [100]
|| [111]
Madelung (1991)
Effective hole masses mh
 in the direction G K
m1 ~=3.16
m2 ~=0.64
m3 ~=0.44
300 K Xu & Ching et al. (1991)
 in the direction G X 0.55mo 300 K Xu & Ching et al. (1991)
 in the direction G L m1 ~=0.36
m2 ~=1.20
300 K Xu & Ching et al. (1991)
Electron affinity 4.5 eV 300 K Rumyantsev et al. (2001)

    Remarks Referens
Dielectric constant (static) 7.1 300 K, infrared reflectivity Gielisse et al.(1967)
Dielectric constant (high frequency) 4.5
4.46
300 K, infrared reflectivity  Gielisse et al.(1967)
Rumyantsev et al. (2001)
Refractive index, n 2.17  300 K,
wavelegth 0.589mm
Gielisse et al.(1967)
Optical phonon energy ~130 meV 300 K
Rumyantsev et al. (2001)
Bulk modulus 400 GPa    
Debye temperature 1700 K    
Melting point, Tm 2973° C also see Termal properties.
Phase diagrams.
Wentorf (1957)
Specific heat ~0.6 J g-1°C -1    
Thermal conductivity
experimentally achieved
7.4 W cm-1 °C -1
   
theoretically estimated ~13 W cm-1 °C -1    
Thermal expansion, linear
1.2·10-6 °C -1    

    Remarks Referens
carrier concentration
and mobility:
     
n
µ
1015 cm-3
0.2 cm2/Vs
500 K, polycrystalline material, type of carrier not determined Bam et al.(1976)
n
µ
1014 cm-3
4 cm2/Vs
900 K, mobility increases exponentially with rising temperature between 500 K and   Bam et al.(1976)

Basic Parameters for Hexagonal crystal structure

    Remarks Referens
Crystal structure Hexagonal    
Group of symmetry D6c-P63mmc    
Number of atoms in 1 cm3    
Debye temperature 400 K    
Density 2.18 g cm-3
2.0-2.28 g cm-3
  Madelung (1991)
Rumyantsev et al. (2001)
Lattice constant, a 2.5040 A
2.5-2.9 A
297 K
300 K
Lynch et al. (1966)
Rumyantsev et al. (2001)
Lattice constant, c 6.6612 A
6.66 A
297 K
300 K
Lynch et al. (1966)
Rumyantsev et al. (2001)
Decomposition temperature, Tdec 2600(100) K Janaf Thermochemical
Tables (1965)
Bulk modulus 36.5 GPa 300 K  
Hardness 1.5 on the Mohs scale  
Phonon wevenumber, v 49 cm-1
E2g, zone center Raman mode Hoffman et al. (1966)
770 cm-1
A2u, infrared active mode  
1367 cm-1
E2g, zone center Raman mode  
1383 cm-1
E1u, infrared active mode  
Brillouin zone of the hexagonal lattice.

    Remarks Referens
Energy gaps, Eg 5.2(2) eV
3.2...5.8 eV
300 K, reflectance
range of experimental data
temperature dependence of resistivity
Hoffmann et al. (1984)
  4.0...5.8 eV 300 K Rumyantsev et al. (2001)
Energy gaps, Eg dir 7.1 eV
  Carpenter & Kirby (1982)
Effective electron mass ml
   in the direction M G
in the direction M L
0.26mo
2.21mo
300 K Xu & Ching et al. (1991)
Effective hole masses mh
 in the direction K G
 in the direction M G
 in the direction M L
0.47mo
0.50mo
1.33mo
300 K Xu & Ching et al. (1991)
Electron affinity 4.5 eV 300 K Rumyantsev et al. (2001)

    Remarks Referens
Dielectric constant (static) =5.06
=6.85
|| to c axis
to c axis
Geick et al.(1966)
Dielectric constant (high frequency) 4.10
4.95
parallel to c axis
perpendicular to c axis
for 300 K;
see also Optical properties.
Dielectric functions
Geick et al.(1966)
  = 2.2;
=4.3
300 K Rumyantsev et al. (2001)
Dielectric constant (static) 7.1 300 K, infrared reflectivity Gielisse et al.(1967)
Dielectric constant (high frequency) 4.5
4.46
300 K, infrared reflectivity  Gielisse et al.(1967)
Rumyantsev et al. (2001)
Refractive index, n 1.65
1.65
2.13
BN- film
perpendicular to c axis
parallel to c axis
Takahashi et al.(1981)
Ishii et al. (1983)
Ishii et al. (1983)
Debye temperature 400 K    
Bulk modulus 36.5 GPa    
Melting point   see Termal properties.
Phase diagrams.
 
Decomposition temperature, Tdec 2600(100) K Janaf Thermochemical Tables (1965)
Specific heat ~0.8 J g-1°C -1    
Thermal conductivity
 parallel to the c axis
perpendicular to the c axis
=<0.3 W cm-1 °C -1
=<6 W cm-1 °C -1
  Rumyantsev et al. (2001)
Thermal expansion, linear
 parallel to the c axis
perpendicular to the c axis
38·10-6 °C -1
-2.7·10-6 °C -1
   

Basic Parameters for Wurtzite, Zinc Blende & Hexagonal crystal structure at 300