Year: 2004
Type: article
Abstract: Bismuth chalcogenides are quite interesting due to their potential as useful thermoelectric materials.1-4Recently, many new ternary and quaternary compounds have been discovered that possess promising thermoelectric property.5,6Furthermore, fundamental interest in these compounds is growing due to their structural diversity they exhibit.For example, the compounds of a general formula of ABiaQs (A=K, Rb, Cs; Q=S, Se, Te)7-11 are known to have six different structure types.The polymorphism is made possible by subtle changes in the edge-sharing modes between the infinite BiQ6 (Q=S, Se) octahedral chains found in the frameworks.Various edge-sharing modes between the octahedral chains can form many types of building units, resulting in a large number of new bismuth chalcogenide frameworks.This is because each BiQ6 octahedron in one chain has maximum 10 edges available for edge-sharing with others in the neighboring chains.If all the 10 edges are shared with ten other BiQ6 octahedra in six neighboring chains, then NaCl-type structure is formed.If fewer edges of an octahedron are to be shared, there are many possible ways of edge-sharing modes to be imagined.For example, (1、 x 3)12 building bar units, formed by sharing edges of BiQ6 octahedra between three chains, are found in a-RbBi3Se5.9 (2 x 3) building bar units, formed by the two (1 x 3) building bar units, are found in a-RbBi3Se5,9 y-RbBi3S5,9 7-RbBi3Se5,9 CsBi3S5,10 gBi^SK),13 and ^BigS*13 Further more, (1 x 2) building bar units in Bi2S3,14 (2 x 2) units in a-RbBi3S5,11 (1 x 4) units in CsBi3Se5,9 and even (1 x 8) units in KBi3S57,8 are found.This suggests that proper utilization of various types of building bar units in well designed reactions will lead to many new compounds with open frameworks or low-dimensional characteristics.Recently, quaternary A/Bi/M/Q (M=Zn, Cd, Mn, Cu; Q=S, Se) systems have been explored and many new compounds of Cs2Bi2MS5 (M=Zn, Cd, Mn),15 K3Bi5Cu2S10,16 RbBi2.66CuSe5,16ABi?CuS4 (A=K, Cs),16」7 and A3Bi5Cu2Sw (A=Rb, Cs)17 are prepared.They contain infinite linear chains of BiQ6 octahedra as well as MQ4 tetrahedra.Once again, (1 x 3) octahedral building bar units in RbBi2.66CuSe516 and (1 x 2) building bar units in Cs2Bi2MS5 (M=Zn, Cd, Mn),15 K3Bi5Cu2S10,16 ABizCuSq (A=K, Cs),16,17 and A3Bi5Cu2S10 (A=Rb, Cs)17 are found.Furthermore, the presence of additional MQ4 tetrahedral infinite chains
Author: Park, Youn-Bong;Choi, Duc-Su;
Institution: Chungnam National University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W378634666