Everything about Boride totally explained
In chemistry a
boride is a chemical compound between boron and a less
electronegative element. This is a very large group of compounds that are generally high melting and are not ionic in nature. Some borides exhibit very useful physical properties. The term boride is also loosely applied to compounds such as B
12As
2 (N.B. Arsenic has an electronegativity higher than boron) that's often referred to as
icosahedral boride.
Ranges of compounds
The borides can be classified loosely as boron rich or metal rich, for example the compound YB
66 at one extreme through to Nd
2Fe
14B at the other. The generally accepted definition is that if the ratio of boron atoms to metal atoms is 4 : 1 or more the compound is boron rich, if it's less then it's metal rich.
Boron rich borides (B:M 4:1 or more)
The main group metals,
lanthanides and
actinides tend to form boron rich borides.
The boron rich group is much larger than the metal rich. The properties of this group vary from one compound to the next, and includes examples of compounds that are semi conductors, superconductors,
diamagnetic,
paramagnetic,
ferromagnetic or
anti-ferromagnetic.. An example is
LaB6 an inert
refractory compound.
Metal rich borides (B:M less than 4:1)
The transition metals tend to form metal rich borides. Metal-rich borides as a group are high melting and inert. Some are easily formed and this explains their use in making turbine blades, rocket nozzles etc. Some examples include
AlB2 and
TiB2. Recent investigations into this class of borides have revealed a wealth of interesting properties such as super conductivity at 39 K in
MgB2 and the ultra-incompressibility of
OsB2 and
ReB2
Boride structures
The boron rich borides contain 3-dimensional frameworks of boron atoms that can include boron polyhedra.
The metal rich borides contain single boron atoms, B
2 units, boron chains or boron sheets/layers.
Examples of the different types of borides are :-
- isolated boron atoms, example Mn4B
- B2 units, example V3B
- chains of boron atoms, example FeB
- sheets or layers of boron atoms CrB2
- 3-dimensional boron frameworks that include boron polyhedra, example NaB15 with boron icosahedra
==
Further Information
Get more info on 'Boride'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://boride.totallyexplained.com">Boride Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |