Manganese disilicide (MnSi₂) is an

intermetallic compound An intermetallic (also called an intermetallic compound, intermetallic alloy, ordered intermetallic alloy, and a long-range-ordered alloy) is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elemen ...

, a silicide of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

. It is a non-stoichiometric compound, with a silicon deficiency expressed as MnSi_2–x. Crystal structures of many MnSi_2–x compounds resemble a chimney ladder and are called

Nowotny phase In inorganic chemistry, a Nowotny chimney ladder phase (NCL phase) is a particular intermetallic crystal structure found with certain binary compounds. NLC phases are generally tetragonal and are composed of two separate sublattices. The first is ...

s. They include MnSi₂ (x=0), Mn₄Si₇ (x=0.250), Mn₁₁Si₁₉ (x=0.273), Mn₁₅Si₂₆ (x=0.267) and Mn₂₇Si₄₇ (x=0.259). These phases have very similar unit cells whose length varies from 1.75 nm for MnSi₂ or Mn₄Si₇, which have almost the same structures, to 11.8 nm for Mn₂₇Si₄₇. Mn4Si7 structure

MnSi_2–x Nowotny phases have a Mn sublattice with a β-

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

structure overlaid with a face-centered cubic Si sublattice. They resemble chimneys of transition metal atoms containing spiraling ladders of Si. These phases are

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

s with a band gap of 0.4 to 0.9 eV. They exhibit a reasonably high thermoelectric figure of merit ZT ~ 0.8 and have potential applications in

thermoelectric generator A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat flux (temperature differences) directly into electrical energy through a phenomenon called the ''Seebeck effect'' (a form of thermoele ...

References

{{Silicides Manganese compounds Transition metal silicides