Characterization of Ag-doped Sb_1.5Bi_0.5Te₃single crystals

Abstract

Single crystals of Sbl.5Bi0.5Te3 doped with Ag atoms ( c A~= 0-3.5 x 10'9atoms/cm3) were characterized by X-ray diffraction, measurement of reflectance in the plasma resonance frequency region, Hall coefficient, electrical conductivity, Seebeck coefficient and the figure of merit. It was found that Ag atoms in the crystal structure of Sbl sBio,5Te3 behave like acceptors; up to the concentration of c~g 1.7 x loL9 atoms/cm3 they increase the hole concentration, whereas in the concentration region of C A~ (1.7-3.5) x 1019atoms/cm3 the hole concentration does not change. The incorporation of Ag atoms into the Sbl.5Bio5Te3 crystal structure results in a decrease in the elementary cell volume and a decrease in the value of figure ofmerit. The increase in the hole concentration is ascribed to the formation of substitutional defects of Ag&, or Ag',,. Besides these defects the formation of interstitial ions of Ag: and four-layer-lamellae of the type [Ago.5Sbo.5]-Te-[Ago.5Sbo.5]-Te is suggested.

Enhanced Thermoelectric Properties of Ag-Modified Bi0.5Sb1.5Te3 Composites by a Facile Electroless Plating Method

“…Among few known ptype dopants, Ag is one of the most widely used elements. Losť'áet al 11 reported that Ag doping can increase the hole concentration due to the formation of negatively charged defects such as Ag Sb ″ or Ag Sb ′ . Recently, various methods, including melting constituent elements, 12 and ball-milling with subsequent thermal decomposition, 13 have been used to dope a small amount of Ag into BST.…”

“…It should be noted that the atomic radius of Ag is a smaller than that of Sb or Bi (r Ag = 0.144 nm, r Sb = 0.159 nm, and r Bi = 0.170 nm). Thus, it can be concluded that Ag can diffuse into BST matrix during the SPS process and Ag can substitute for Sb 11 or Bi 17 considering if the fine Ag particles can be molten (T m ≈ 623 K 18 ) at 673 K.…”

“…The increase of the n can be ascribed to the existence of Ag and the formation of substitutional defects. 11,17 Figure 2b shows the temperature dependent S of Ag/BST bulks. The S of commercial BST increases with increasing temperature before 350 K, suggesting that the electrical transports are mainly dominated by holes.…”

Control of Carrier Concentration by Ag Doping in N-Type Bi2Te3 Based Compounds

“…Lee et al reported that ρ and α decreased with Ag, which substituted for Bi or Sb in p-type (Bi,Sb) 2 Te 3 [17]. The substitution of Ag for Bi or Sb was also reported by Klichová et al [18]. All of these results said that the Ag acted as an acceptor in the p-type (Bi,Sb) 2 Te 3 compounds.…”

Method of Efficient Ag Doping for Fermi Level Tuning of Thermoelectric Bi0.5Sb1.5Te3 Alloys Using a Chemical Displacement Reaction

“…18 Trends in the lattice parameter have also been investigated for Ag doping in BST. In previous studies, [8][9] the cell volume decreased at higher Ag concentrations due to the smaller size of Ag when compared to Bi or Sb. However, almost no variation in the cell volume was observed for the samples in this work (Table S1).…”