Percolation effects and self-organization processes in cold-pressed Bi2(Te1−xSex)3 solid solutions

Thermal conductivity of solid solutions of Bi2(Te1-xSex )3 (x = 0-0.07)

“…Earlier in the study of concentration dependencies S and σ cast and cold-pressed samples of the system Bi 2 (Te 1-x Se x ) 3 , the authors of this study observed anomalies of properties near the composition x = 0.01, the presence of which was associated with the phase transition (PT) from diluted to concentrated solid solution [13]. Similar anomalies were observed earlier in [14] for a large number of solid solutions.…”

“…The highest received value of Z corresponds to the composition x=0.07 and amounts to Z ~2.1 10 -3 K -1 which within the error limit of the definition of Z coincides with the maximum value of Z, which was observed in [19] for composite materials. The results of this study, together with the results of [13], demonstrate that percolation PT affects all TE properties of SS of Bi 2 (Te 1-x Se x ) 3 , leading to an increase in electrical and thermal conductivity and a decrease in S in the area near x=0.01. But the effect of percolation PT on the TE figure of merit is determined by a combination of these parameters.…”

“…Abnormal growth of λ in the interval x=0.005-0.01 is an additional evidence that in the specified range of compositions, transformations in the crystal are implemented during the formation of SS, which affect the processes of phonon scattering. As in previous studies [13], it is advisable to associate these transformations with the implementation of PT from diluted to concentrated solid solution. The likely mechanism for implementing these processes is described in detail in the review paper [14], which also provides a number of experimental confirmations of this hypothesis.…”

“…In [13], the TE values of the parameters of coldpressed and annealed samples Bi 2 (Te 1-x Se x ) 3 were determined, namely, the electrical conductivity and Seebeck coefficient. Supplementing these data with the values of λ obtained in this study, the values of TE figure of merit Z for these SS at room temperature were calculated.…”

Percolation Process-Mediated Rich Defects in Hole-Doped PbSe with Enhanced Thermoelectric Performance

“…It is worth noting that Sn atoms were previously reported to exclusively substitute Pb atoms in Pb 1– y Sn y Se ( y > 0.2) alloys. The significantly different defect chemistry of Sn in lightly and heavily SnSe-alloyed PbSe might originate from the percolation effect, which has been investigated for several decades in the fields of semiconductor, metallurgy, polymer physics, and so on. − In dilute solid solutions of hole-doped PbSe–SnSe, Sn atoms are well separated from each other, and the interactions between Sn dopants can be ignored. Under this circumstance, the introduction of Sn atoms gradually increases the configuration entropy of the system, which facilitates the formation of diverse defects (Sn i 4+ , Sn Pb , and V Pb ) as demonstrated by our microscopy study and positron annihilation measurements.…”