Premium
Defect structure of thermoelectric Zn 4 Sb 3
Author(s) -
Zhang T.,
Zhou K.,
Chen Z. Q.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552079
Subject(s) - positron , spark plasma sintering , materials science , positron annihilation spectroscopy , doppler broadening , vacancy defect , thermoelectric effect , electrical resistivity and conductivity , interstitial defect , phase (matter) , phase transition , positron lifetime spectroscopy , condensed matter physics , positron annihilation , atomic physics , crystallography , chemistry , microstructure , doping , electron , nuclear physics , spectral line , physics , thermodynamics , metallurgy , optoelectronics , organic chemistry , quantum mechanics , astronomy
Abstract Thermoelectric β − Zn 4 Sb 3 samples prepared by spark plasma sintering method have been studied by resistivity measurement, X‐ray diffraction (XRD) and positron annihilation spectroscopy (PAS). The existence of Zn vacancies in β − Zn 4 Sb 3 structure is confirmed by PAS, which contribute a positron lifetime component of 212 ± 3 ps. Positron lifetime calculation has been performed for different defect structural models of β − Zn 4 Sb 3 . By comparing the calculated lifetime values with the experimental result, we find that each Zn vacancy must have at least two close interstitial Zn atoms in the crystal structure of β − Zn 4 Sb 3 . Two separate phase transitions observed by resistivity measurement occur at about 232 and 252 K, whereas the positron annihilation measurements indicate they are about 225 and 240 K. Positron lifetime and Doppler broadening results reveal α ′ phase is a transition phase between α and β phases. The results also indicate the disordering of interstitial clusters into interstitial Zn sites during the α ′ to β phase transition. The interstitial Zn clusters are found to act as shallow positron traps which apparently capture positrons below 200 K.