Chalcogenide
- Practical Electron Microscopy and Database -
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Chalcogenide alloys (or sometimes called glasses) are a type of chemical compounds consisting of at least one chalcogen ion and one or more electropositive elements. The name is more commonly reserved for sulfides, selenides, and tellurides, rather than oxides, even though all group 16 elements of the periodic table are defined as chalcogens as shown in Table 3480a. By changing chemical compositions, most chalcogenide glasses display three elastic phase: floppy phase, isostatically rigid phase and stressed rigid phase. Table 3480b shows the standard oxidation potentials for chalcogenide anions.

Table 3480a. Chalcogen ions marked in green background. The elements in most common chalcogenides are indicated in red.

1 2   3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1   2
H   He
3 4   5 6 7 8 9 10
Li Be   B C N O F Ne
11 12   13 14 15 16 17 18
Na Mg   Al Si P S Cl Ar
19 20   21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
K Ca   Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
37 38   39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Rb Sr   Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
55 56   71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
Cs Ba {57-70} Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
87 88 103 104 105 106 107 108 109 110 111 112 114
Fr Ra [89-102] Lr Rf Db Sg Bh Hs Mt Ds Uuu Uub   Uuq
 
57 58 59 60 61 62 63 64 65 66 67 68 69 70    
{lanthanides} {57-70} La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Th Yb    
89 90 91 92 93 94 95 96 97 98 99 100 101 102
{actinides} [89-102] Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No    
 

Table 3480b. The standard oxidation potentials for chalcogenide anions.

Anion
Standard oxidation potential
Oxide
O2- - 2e- → O0, E0ox = - 3 V
Sulfide
S2- - 2e- → S0, E0ox = - 0.476 V
Disulfide
S22- - 2e- → 2S0, E0ox = - 0.428 V
Selenide
Se2- - 2e- → Se0, E0ox = - 0.924 V
Telluride
Te2- - 2e- → Te 0, E0ox = - 1.143 V

Table 3480c. Various classes of amorphous chalcogenide systems.

Class

Examples
Pure chalcogenide
S, Se, Te, SxSe1-x
Pnictogen-chalcogen (V-VI)
As2S3, P2Se
Teratogen-chalcogen (IV-VI)
SiSe2, GeS2
III-VI
B42S3, InxSe1-x
Metal chalcogenide
MoS3, WS3, Ag2S-GeS2

Chalco-halides

As-Se-I, Ge-S-Br, Te-Cl

Chalcogenide alloys have been applied in several areas:
        i) Infrared optical fibers.
        ii) Infrared windows.
        iii) Photovoltaic devices.
        iv) Phase change optical storage media.
        v) Rewritable phase-change optical memory disks.
        vi) Rewritable digital versatile disks.
        vii) Nonvolatile electrical memory devices.

 

 

 

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