Improved carrier concentration control in Zn-doped Ca5Al2Sb6

Abstract

Ca 5 Al 2 Sb 6 is an inexpensive, Earth-abundant compound that exhibits promising thermoelectric efficiency at temperatures suitable for waste heat recovery. Inspired by our previous study of p-type Ca 5Àx Na x Al 2 Sb 6 , this work investigates doping with Zn 2þ on the Al 3þ site (Ca 5 Al 2Àx Zn x Sb 6 ). We find Zn to be an effective p-type dopant, in contrast to the low solubility limit and poor doping efficiency of Na. Seebeck coefficient measurements indicate that the hole band mass is unaffected by the dopant type in the high-zT temperature range. Band structure and density of states calculations are employed in order to understand the carrier concentration-dependent effective mass. Ca 5 Al 2Àx Zn x Sb 6 has a low lattice thermal conductivity that approaches the predicted minimum value at high temperature (1000 K) due to the complex crystal structure and high mass contrast.

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr3AlSb3

“…Sb 6 , in which the substitution of Zn 2+ on the Al 3+ site leads to an increase in carrier concentration by two orders of magnitude and a clear transition from nondegenerate to degenerate semiconducting behavior. 28 Structural differences between the A 5 Al 2 Sb 6 phases, in addition to the possible influence of the cation on the stability of acceptor defects (e.g., Sr vacancies and Zn substitution on Al site), could explain this disparity. In previous studies, Na 1+ on the Ca 2+ site was a successful dopant in both Ca 5 Al 2 Sb 6 and Ca 3 AlSb 3 compounds, 16,18 suggesting that similar substitutions may prove successful in increasing the carrier concentration in Sr 5 Al 2 Sb 6 .…”

Two-step sintering of nanocrystalline Cu(In0.7Ga0.3)Se2

“…The main factor determining drift velocity is scattering time. The most important sources of scattering in typical semiconductor materials include (a) boundary scattering from pores or grain boundaries, (b) activation barrier at grain boundaries, (c) local strain field, or (d) ionized impurity scattering [19]. Sanyal et al [20] investigated the electrical conductivity and Hall mobility measurements on CIS films and observed that scattering at the grain boundaries is a predominant factor in controlling the electron transport properties at low temperatures.…”

Effect of electron doping on thermoelectric properties for narrow-bandgap intermetallic compound RuGa2

“…This model provides a reasonable lowest j phonon value in disordered materials, 24 amorphous, 25 and structurally complex solids such as Zintl-phases 26 and icosahedral quasicrystals 27 . The calculated j min over 300 K for the RuGa 2 is almost the constant value of 1.0 W m À1 K À1 .…”