Difference between revisions of "Magnesium diboride"
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Unlike elemental [[boron]] whose combustion is incomplete through the glassy oxide layered impeding oxygen diffusion, magnesium diboride burns completely when ignited in oxygen or in mixtures with oxidizers. | Unlike elemental [[boron]] whose combustion is incomplete through the glassy oxide layered impeding oxygen diffusion, magnesium diboride burns completely when ignited in oxygen or in mixtures with oxidizers. | ||
| − | Magnesium diboride has been shown that to be a good replacement in classical decoy flares. Magnesium diboride/[[Teflon]]/[[Viton]] decoy flares display 30–60% increased spectral efficiency, E<sub>λ</sub> (J g<sup>−1</sup>sr<sup>−1</sup>), compared to classical Magnesium/Teflon/Viton(MTV). payloads. | + | Magnesium diboride has been shown that to be a good replacement in classical decoy flares. Magnesium diboride/[[Polytetrafluoroethylene|Teflon]]/[[Viton]] decoy flares display 30–60% increased spectral efficiency, E<sub>λ</sub> (J g<sup>−1</sup>sr<sup>−1</sup>), compared to classical Magnesium/Teflon/Viton(MTV). payloads. |
===Physical=== | ===Physical=== | ||
Latest revision as of 16:18, 2 January 2022
| Names | |
|---|---|
| IUPAC name
Magnesium diboride
| |
| Preferred IUPAC name
Magnesium diboride | |
| Other names
Magnesium boride
| |
| Properties | |
| MgB2 | |
| Molar mass | 45.93 g/mol |
| Appearance | Dark gray solid |
| Odor | Odorless |
| Density | 2.57 g/cm3 |
| Melting point | 830 °C (1,530 °F; 1,100 K) (decomposes) |
| Boiling point | (decomposes) |
| Insoluble | |
| Solubility | Insoluble in organic solvents |
| Vapor pressure | ~0 mmHg |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
826 mg/kg (rat, oral) |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Magnesium diboride is the inorganic compound with the formula MgB2
Contents
Properties
Chemical
Magnesium diboride reacts with dilute acids to release hydrogen and a small amount of boranes, while reaction with water evolves hydrogen, without any traces of boranes. Both reactions also produce lots of heat.[1][2]
Magnesium diboride has been shown to react with KOH to produce borohydrides. The reaction is relative slow, and after 9-12 hours, the yield of the reaction is around 20%.[3]
Unlike elemental boron whose combustion is incomplete through the glassy oxide layered impeding oxygen diffusion, magnesium diboride burns completely when ignited in oxygen or in mixtures with oxidizers.
Magnesium diboride has been shown that to be a good replacement in classical decoy flares. Magnesium diboride/Teflon/Viton decoy flares display 30–60% increased spectral efficiency, Eλ (J g−1sr−1), compared to classical Magnesium/Teflon/Viton(MTV). payloads.
Physical
Magnesium diboride is a dark gray solid, insoluble in water and organic solvents.
Magnesium diboride becomes superconducting at 39 K (−234 °C), a relative high temperature for classical low-temperature superconductors.
Availability
Magnesium diboride is sold by chemical suppliers.
Preparation
The simplest synthesis involves high temperature reaction between boron and magnesium powders in an inert atmosphere. Formation begins at 650 °C; however, since magnesium metal melts at 652 °C, the reaction may involve diffusion of magnesium vapor across boron grain boundaries.
Projects
- Demonstration of superconductivity
- Make decoy flares
Handling
Safety
Magnesium diboride
Storage
In closed bottles, bags or boxes
Disposal
No special disposal is required, can be dumped in trash.
References
- ↑ https://arxiv.org/ftp/arxiv/papers/0912/0912.4906.pdf
- ↑ https://pubs.rsc.org/-/content/articlelanding/1935/jr/jr9350001694
- ↑ https://pubs.acs.org/doi/pdf/10.1021/ja01597a093
