The Effects of Sintering Conditions and Processes on the Thermoelectric and Tribological Properties of High Manganese Silicide Mn₄Si₇

Abstract

Triboelectric nanogenerator as new energy technology needs to develop new triboelectric semiconductor materials with excellent electrical transport properties and friction properties for better electric output performance. High manganese silicide Mn 4 Si 7 bulks were prepared from Mn powders and Si powders at 1273 K for 1 h. The residual Si phase and MnSi phase coexisted in the primary sintered Mn 4 Si 7 compacts. The fine Mn powder obtained from mechanical pulverization and secondary sintering can accelerate the formation of Mn 4 Si 7 bulks. MnSi disappeared and slight amount of Si phase remained in the secondary sintered Mn 4 Si 7 bulks. Due to the slight decrease in the resistivity, ZT of Mn 4 Si 7 bulks reached 0.43 at 813 K. The thermal conductivity of the secondary sintered Mn 4 Si 7 compact increased due to the pulverization of the primary Mn 4 Si 7 bulk and the growth of crystal grains. The thermoelectric properties of Mn 4 Si 7 compact are reduced after heat treatment. Secondary sintering can increase the density of Mn 4 Si 7 compact. For the friction property of Mn 4 Si 7 , secondary sintering and heat treatment can reduce the coefficient friction and mass loss of primary sintered Mn 4 Si 7 compact. Based on the excellent thermoelectric properties and low wear loss at low loads of Mn 4 Si 7 , it is possible to be employed as new triboelectric materials for triboelectric nanogenerator.

Discordant Doping and Labile Silicon Atoms in Higher Manganese Silicide

“…Different compositions or stoichiometries of HMSs may coexist incommensurately among which Nowotny Chimney Ladder (NCL) phases are distinctively identified, which constitute of two tetragonal subsystems of [Mn] and [Si] having an incommensurate c -axis, wherein Si atoms forming a ladder are enclosed by Mn atoms arranged as a chimney. , Having an odd stoichiometry, these silicon-rich NCL phases are denoted by MnSi γ , wherein γ as the component of modulation vector (00γ) is defined using c -axis length ratio γ = c Mn / c Si of [Mn] and [Si] subsystems. , Stoichiometrically, γ corresponds to odd Si/Mn stoichiometry and has been found to vary in the range of 1.72 to 1.75, which depends on several factors such as the nominal composition, dopant, thermal history, and synthesis methodology. ,− The accurate evaluation of structural parameters modulated by inherent incommensurability in HMS alloys is possible within the theoretical framework of the (3 + 1)-dimensional superspace approach, which characteristically reveals that γ can be varied favorably by choosing the appropriate dopants to alter γ favorably. − …”