Index
Ctrl+clic to navigate
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
1
|
1
H
|
Raw critical materials
|
2
He
|
2
|
3
Li
|
4
Be
|
|
5
B
|
6
C
|
7
N
|
8
O
|
|
9
F
|
|
10
Ne
|
3
|
11
Na
|
12
Mg
|
13
Al
|
14
Si
|
15
P
|
16
S
|
17
Cl
|
18
Ar
|
4
|
19
K
|
20
Ca
|
21
Sc
|
22
Ti
|
23
V
|
24
Cr
|
25
Mn
|
26
Fe
|
27
Co
|
28
Ni
|
29
Cu
|
30
Zn
|
31
Ga
|
32
Ge
|
33
As
|
34
Se
|
|
35
Br
|
|
36
Kr
|
5
|
37
Rb
|
38
Sr
|
39
Y
|
40
Zr
|
41
Nb
|
42
Mo
|
43
Tc
|
44
Ru
|
45
Rh
|
46
Pd
|
47
Ag
|
48
Cd
|
49
In
|
50
Sn
|
51
Sb
|
52
Te
|
|
53
I
|
|
54
Xe
|
6
|
55
Cs
|
56
Ba
|
57
La
|
|
72
Hf
|
73
Ta
|
74
W
|
75
Re
|
76
Os
|
77
Ir
|
78
Pt
|
79
Au
|
80
Hg
|
81
Tl
|
82
Pb
|
83
Bi
|
84
Po
|
|
85
At
|
|
86
Rn
|
7
|
87
Fr
|
88
Ra
|
89
Ac
|
|
104
Rf
|
105
Db
|
106
Sg
|
107
Bh
|
108
Hs
|
109
Mt
|
110
Ds
|
111
Rg
|
112
Cn
|
113
Uut
|
114
Fl
|
115
Uup
|
116
Lv
|
|
117
Uus
|
|
118
Uuo
|
|
Lanthanides
|
58
Ce
|
59
Pr
|
60
Nd
|
61
Pm
|
62
Sm
|
63
Eu
|
64
Gd
|
65
Tb
|
66
Dy
|
67
Ho
|
68
Er
|
69
Tm
|
70
Yb
|
71
Lu
| |
Actinides
|
90
Th
|
91
Pa
|
92
U
|
93
Np
|
94
Pu
|
95
Am
|
96
Cm
|
97
Bk
|
98
Cf
|
99
Es
|
100
Fm
|
101
Md
|
102
No
|
103
Lr
| |
Other raw Critical materials
Coal coke
|
CaF2
|
MgCO3
|
Natural graphite
|
Phosphate rocks
|
Rare earth elements
|
Back to the index
Candini Chiara, Puggioli Christian, Radi Silvia
Germanium (Ge)
Germanium is a metal placed in IV A in the periodic table. In 1869, Dmitri Mendeleev predicted its existence and some of its properties based on its position on the periodic table. In 1886, Clemens Winkler found the new element along with silver and sulphur, in a rare mineral called argyrodite. Winkler named the element after his country, Germany 1.
Uses:
Germanium is a semiconductor and used as a transistor in thousands of electronic applications:
-
Photovoltaics (conversion of electromagnetic radiation as sunlight, into electricity);
-
Fibre optics → germanium increases refractive index;
-
Infrared vision → germanium uses its transparency to infrared reaction;
-
Catalyst in organic chemistry2;
Properties
Germanium is a hard, brittle, lustrous, semi-conducting metal and is similar in chemical and physical properties to silicon.
It is also stable in air and water.
Characteristics
You can find germanium also in zinc minerals and in by-products of combustion of some coals.
Germanium minerals are very rare and are found in small quantities 3; because of this characteristic it is a critical material and it will be probably substituted by silicon in future.
A consequence is the rising back of germanium’s price (after decreasing until the middle of 2012), even higher level than before 4.
Origin
The production of germanium is about 80 tonnes per year.
China is the major producer of germanium, followed by the Ukraine and Russia5
Solutions
The 30% of the worldwide consumption comes from recycled germanium. The 80% of fibre optic scarp are recycled6 and also the 50% of germanium metal used for electronic and optic are recycled.
The best substitute of germanium is Silicon (that is also less-expensive) for some electronic applications7
References
-
https://en.wikipedia.org/wiki/Germanium
-
Butterman W.C., Jorgenson JD (2005) Germanium. Open-File Report 2004-1218
-
http://www.rsc.org/periodic-table/element/32/germanium
-
Metal Bulletin Germanium Metal Rotterdam $/Kg; Lastes Metal Prices Tracking and Comparison Toll. ( http://www.metalbulletin.com/My-price-book.html?price=42087. Accessed 3 September 2013 )
-
Ad-hoc Working Group on defining critical raw materials (2010) Critical raw materials for the EU: European Commission
-
Bell Labs-Lucent technology Bell Labs Innovative Germanium-Recovery Process is Economically, Enviromentally Friendly. Science Daily.
-
Guberman, D.E. (2013) Germanium, in: U.S. Geological Survey (ed.) Mineral commodity summaries 2013
Back to the index
Candini Chiara, Puggioli Christian, Radi Silvia
Gallium
Gallium is a soft, silvery metal with symbol Ga and atomic number 31. It’s a by-product of aluminium and in its pure, solid form, it is silvery white and has a fracture pattern similar to glass.
Gallium comes from the latin name for France, Gallia. It also has origins in the Latin word gallus, a translation of Lecoq, wich means “rooster” and is also the first name of the scientist who discovered the element: Paul Emile Lecoq de Boisbaudran. The latter observed two new violet lines in the atomic spectrum of some zinc. He knew it meant that an unknown element was present, but its existence, and properties, had been predicted by Mendeleev who had left a gap below aluminium in his periodic table.
USE
The commercial use of gallium is dominated by the semiconductor applications (98%).
-
It is used to create very shiny mirrors
-
Gallium arsenide is a useful silicon substitute for the electronics industry. It is an important component of many semiconductors.
-
Thanks to its ability to convert electricity to light it is used in red LEDs (light emitting diodes). Solar panels on the Mars Exploration Rover contained gallium arsenide.
-
It has important uses in Blu-ray technology, mobile phones and pressure sensors for touch switches.
-
Gallium readily alloys with most metals. It is particularly used in low-melting alloys.
-
It has a high boiling point, so it's used for recording very high temperatures that would vaporise a thermometer.
Dostları ilə paylaş: |