Influence of structures and compositions on thermoelectric properties of silicon borides

A Review of Boron-Rich Silicon Borides Basedon Thermodynamic Stability and Transport Properties of High-Temperature Thermoelectric Materials

“…In addition, the CVD process shows extraordinary electrical conductivity for boron-rich Si-B systems compared to other melting processes. This confirms the fact that the electrical conductivity is affected by melting, which creates microcracks or inner porosity during the solidification [49].…”

“…(8) and 9, we obtain Figure 7: A semi log (Arrhenius-type) plot of ln (σ) versus T −1 : SPS SiB 6 + SiB n [45], SPS SiB n [45], AM SiB 6 + SiB n [45], AM SiB n [45], AM-SiB 6 [46], AM-SiB 4 + SiB 6 [46], Sintering [47], CVD SiB 6 [48], CVD SiB 4 [48], CVD SiB n (B/Si = 60) [49], CVD SiB n (B/Si = 48), SPS SiB 6 [50], HP SiB 6 [50], Plasma melting [49], SPS Si 92 B 8 [51]. SPS SiB 6 + SiB n [45], SPS SiB n [45], AM SiB 6 + SiB n [45], AM SiB n [45], AM-SiB 6 [46], AM-SiB 4 + SiB 6 [46], Sintering [47], CVD SiB 6 [48], CVD SiB 4 [48], CVD SiB n (B/Si = 60) [49], CVD SiB n (B/Si = 48), SPS SiB 6 [50], HP SiB 6 [50], Plasma melting [49], SPS Si 92 B 8 [51]. Figure 9: A semi-log (Arrhenius-type) plot of ln k versus T −1 : SPS SiB 6 + SiB n [45], SPS SiB n [45], AM SiB 6 + SiB n [45], AM SiB n [45], AM-SiB 6 [46], AM-SiB 4 + SiB 6 [46], Sintering [47], CVD SiB 6 [48], CVD SiB 4 [48], SPS Si 92 B 8 [51].…”

“…The SiB n and SiB 6 phases have comparatively higher Seebeck coefficients. The wide range of non-stoichiometric, chemical compositions of SiB n is the reason for this higher Seebeck coefficient [49]. Figure 6 shows not only the temperature dependence of Seebeck coefficient for different phases/ compositions, but also the effect of the processing method.…”

“…The Seebeck coefficient also depends on the microstructure, i.e. grain size and the amount of twin boundaries, of the system [49]. The grain size and twin boundaries are, of course, different in different procedures, causing the differences in the Seebeck coefficient.…”

“…As seen in Figure 7, the electrical conductivity increases with an increase in temperature for every processing method. This behavior suggests the degenerated performance of the Si-B system [62] resulting from its semiconductor-like behavior at a high temperature [49]. A high temperature causes small polar ion hopping to produce an Arrhenius type relationship which is a thermally activated conductivity with a temperature dependent prefactor for semiconductor properties [63].…”