【VIP专享】金属硼化物结构与性能
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prepared by: luokan
Contents
• Structure of some typical metal borides • Properties and application of some metal
borides
– MgB2 – ZrB2 – CaB6 …
• Conclusion
Metal Borides
Metal Borides
Metal Borides
One single cell of YB66
Metal Borides
MgB2
Magnesium diboride (MgB2) is a simple ionic binary compound that has proven to be an inexpensive and useful superconducting material. Density 2.57 g/cm3 Melting point 830℃
– (Vajpayee A, Awana V P S, Balamurugan S, et al. Effect of PVA doping on flux pinning in bulk MgB2[J]. Physica C: Superconductivity. 2007, 466(1–2): 46-50.)
Metal Borides: Structure and Performance
Carenco S, Portehault D, Boissière C, et al. Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives[J]. Chemical Reviews. 2013, 113(10): 7981-8065.
• Two types of doping to improve the superconductivity of MgB2
– Mg1-xMxB2(Al, Be, Ca, Cu, Li, Na, Zn…) – MgB2-yXy(Be, C, N, O…)
MgB2
• Various means of doping MgB2 with carbon can improve the upper critical field and the maximum current density, 5% doping with carbon can raise Hc2 from 16 T to 36 T whilst lowering Tc only from 39 K to 34 K
α-boron
Density(g/cm3) 2.46
Vickers Hardness(GPa)
42
Bulk Modulus(GPa)
185
Bandgap(eV) 2
wk.baidu.com
β-boron
2.35
45
224
1.6
Liu G, Niu P, Yin L, et al. α-Sulfur Crystals as a Visible-Light-Active Photocatalyst[J]. Journal of the American Chemical Society. 2012, 134(22): 9070-9073.
• Boron can form a metal boride with almost all metals at high temperatures
• Metal Borides(MmBn) tend to form interstitial compouds,
Boron polymorphs
β-rhombohedral boron
Metal Borides
• Boron is a chemical element with symbol B and atomic number 5
• Boron (B) naturally occurs in two isotopes, 10B and 11B, the latter of which makes up about 80% of natural boron
MgB2
• Its superconductivity was discovered by the group of Akimitsu in 2001. Its critical temperature (Tc) of 39 K is the highest amongst conventional superconductors. This material was first synthesized and its structure confirmed in 1953 but its superconducting properties were not discovered until 2001.
MgB2
The temperature dependences of the normalized resistivity ρ(T)/ρ(300 K)for the samples of MgB2, Mg0.98Ca0.02B2 and Mg0.92Ca0.08B2.
Sun Y, Yu D, Liu Z, et al. Structural and superconducting properties of Ca-doped MgB2 superconductors[J]. Superconductor Science and Technology. 2007, 20(3): 261.
• 20% Cu doping MgB2 raise Tc to 49K, and Tc0 = 45.6 K
– (Sun Y P, Song W H, Wen H H, et al. Superconductivity at 49 K in copper doping magnesium diboride[Z]. 2001.)
Contents
• Structure of some typical metal borides • Properties and application of some metal
borides
– MgB2 – ZrB2 – CaB6 …
• Conclusion
Metal Borides
Metal Borides
Metal Borides
One single cell of YB66
Metal Borides
MgB2
Magnesium diboride (MgB2) is a simple ionic binary compound that has proven to be an inexpensive and useful superconducting material. Density 2.57 g/cm3 Melting point 830℃
– (Vajpayee A, Awana V P S, Balamurugan S, et al. Effect of PVA doping on flux pinning in bulk MgB2[J]. Physica C: Superconductivity. 2007, 466(1–2): 46-50.)
Metal Borides: Structure and Performance
Carenco S, Portehault D, Boissière C, et al. Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives[J]. Chemical Reviews. 2013, 113(10): 7981-8065.
• Two types of doping to improve the superconductivity of MgB2
– Mg1-xMxB2(Al, Be, Ca, Cu, Li, Na, Zn…) – MgB2-yXy(Be, C, N, O…)
MgB2
• Various means of doping MgB2 with carbon can improve the upper critical field and the maximum current density, 5% doping with carbon can raise Hc2 from 16 T to 36 T whilst lowering Tc only from 39 K to 34 K
α-boron
Density(g/cm3) 2.46
Vickers Hardness(GPa)
42
Bulk Modulus(GPa)
185
Bandgap(eV) 2
wk.baidu.com
β-boron
2.35
45
224
1.6
Liu G, Niu P, Yin L, et al. α-Sulfur Crystals as a Visible-Light-Active Photocatalyst[J]. Journal of the American Chemical Society. 2012, 134(22): 9070-9073.
• Boron can form a metal boride with almost all metals at high temperatures
• Metal Borides(MmBn) tend to form interstitial compouds,
Boron polymorphs
β-rhombohedral boron
Metal Borides
• Boron is a chemical element with symbol B and atomic number 5
• Boron (B) naturally occurs in two isotopes, 10B and 11B, the latter of which makes up about 80% of natural boron
MgB2
• Its superconductivity was discovered by the group of Akimitsu in 2001. Its critical temperature (Tc) of 39 K is the highest amongst conventional superconductors. This material was first synthesized and its structure confirmed in 1953 but its superconducting properties were not discovered until 2001.
MgB2
The temperature dependences of the normalized resistivity ρ(T)/ρ(300 K)for the samples of MgB2, Mg0.98Ca0.02B2 and Mg0.92Ca0.08B2.
Sun Y, Yu D, Liu Z, et al. Structural and superconducting properties of Ca-doped MgB2 superconductors[J]. Superconductor Science and Technology. 2007, 20(3): 261.
• 20% Cu doping MgB2 raise Tc to 49K, and Tc0 = 45.6 K
– (Sun Y P, Song W H, Wen H H, et al. Superconductivity at 49 K in copper doping magnesium diboride[Z]. 2001.)