二ほう化マグネシウム 化學(xué)特性,用途語,生産方法
解説
二ホウ化マグネシウム:MgB2(45.93)．六方晶系で，Bは平面グラファイト型につながり，Mgは層間に入る．低溫超伝導(dǎo)物質(zhì)としては異常に高い－234 ℃ で超伝導(dǎo)を示す．
特徴
XDS. 超伝導(dǎo)體. Tc 39 K. 単位格子の頂點(diǎn)にMg, (1/3, 2/3, 1/2), (2/3, 1/3, 1/2)にB原子があり, MgとB原子が各層を形成する. 空間群P6/mmm, a 3.0851(5), c 352.01(5) pm, B?B 178 pm, Mg?B 250 pm.
説明
Magnesium diboride (MgB
2) is a simple ionic binary
compound that has proven to be an inexpensive and
useful superconducting material.
化學(xué)的特性
Magnesium Boride is brown solid, by reaction of boron oxide and magnesium powder ignited.
物理的性質(zhì)
Its molecular weight is 45.9325 g/mol. Magnesium Boride melts at 830°C
and is hexagonal with space group P6/mmm and lattice
constants of a=3.0864 , c=3.5215 . The density is
2.625 g/cm
3 and the hardness is 1260 kg/mm
2.
使用
Magnesium Boride exhibits super conducting properties and utilized in MRI superconducting magnet, which is a closed-loop cryocooler. It is used as propellants, pyrotechnics and explosives. It can be used as high temperature boron-based thermoelectric materials. It is also used in superconducting transformers, rotors, transmission cables, superconducting radio frequency cavities to minimize energy loss.
製造方法
Magnesium boride can be formed directly from the
elements. Mg melts at 650 °C and boron melts at
2076 °C. Therefore, if a vapor of Mg metal at >750°C
(red-heat) is passed over crystals of boron, reaction
forms the desired boride. However, to obtain a stoichiometric
compositions, it is better to heat the well-mixed
powders of Mg and B to obtain specific compounds:
Mg + 2B→MgB
2
一般的な説明
Magnesium boride (MgB
2) powder is a superconductive material which has a critical temperature (Tc) = 39K. It can be used for a variety of applications such as hydrogen storage, high energy fuel and high field superconductors.
參考文獻(xiàn)
S. Lee, et al., J. Phys. Soc. Jpn., 70, 2225 (2001).
二ほう化マグネシウム 上流と下流の製品情報(bào)
原材料
準(zhǔn)備製品