High performance thermoelectric materials and their method of preparation

Abstract

The present invention provides an indium-doped Co 4 Sb 12 skutterudite composition in which some Co on the cubic lattice structure may be replaced with one or more members of the group consisting of Fe, Ni, Ru, Rh, Pd, Ir and Pt; some Sb on the planar rings may be replaced by one or more members of the group consisting of Si, Ga, Ge and Sn; and a second dopant atom is selected from a member of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. The composition is useful as a thermoelectric material. In preferred embodiments, the composition has a figure of merit greater than 1.0. The present invention also provides a process for the production of the composition, and thermoelectric devices using the composition.

1 . A composition of matter having a skutterudite cubic lattice structure comprised of a purality of cubic unit cells, wherein
 (a) the cubic lattice of a cubic unit cell is comprised of Co, or Co and one or more members of the group consisting of Fe, Ni, Ru, Rh, Pd, Ir and Pt;   (b) a cubic unit cell is comprised of atomic crystallograhphic sites arranged in eight subcells;   (c) six subcells in a first cubic unit cell are comprised of Sb, or Sb and one or more members of the group consisting of Si, Ga, Ge and Sn;   (d) a seventh subcell in the first cubic unit cell is comprised of In; and   (e) an eighth subcell in the first cubic unit cell is comprised of a member of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.   
     
     
         2 . The composition of  claim 1  further comprising a second cubic unit cell in which the eighth subcell is comprised of a different member of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu than the eighth subcell in the first cubic unit cell. 
     
     
         3 . The composition of  claim 1  further comprising a second cubic unit cell in which the eighth subcell is comprised of In. 
     
     
         4 . The composition of  claim 1  further comprising a second cubic unit cell in which the seventh and eighth subcells are both comprised of a member of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. 
     
     
         5 . The composition of  claim 4  wherein the seventh and eighth subcells are comprised of the same member of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. 
     
     
         6 . The composition of  claim 4  wherein the seventh and eighth subcells are comprised of different members of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. 
     
     
         7 . The composition of  claim 1  which is described by the formula Co 4-m A m Sb 12-n X n In x M y , where A is selected from one or more members of the group consisting of Fe, Ni, Ru, Rh, Pd, Ir and Pt; X is selected from one or more members of the group consisting of Si, Ga, Ge and Sn,; M is selected from one or more members of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; 0≦m≦1; 0≦n≦9; 0<x<1; 0<y<1; and 0<x+y≦1. 
     
     
         8 . The composition of  claim 1  which comprises
 about 23.5 to about 25 atomic per cent Co, or Co and one or more members of the group consisting of Fe, Ni, Ru, Rh, Pd, Ir and Pt;   about 70.5 to about 75 atomic per cent Sb, or Sb and one or more members of the group consisting of Si, Ga, Ge and Sn;   about 0.001 to about 0.06 atomic percent of In; and   about 0.001 to about 0.06 atomic percent of one or more members of the group consisting of Ca, Sc, Zn, Sr, Y, Pd, Ag, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.   
     
     
         9 . The composition of  claim 1  wherein the cubic lattice of the cubic unit cell is comprised of Co. 
     
     
         10 . The composition of  claim 1  wherein the six subcells are comprised of 4-member planar rings comprised of Sb. 
     
     
         11 . A composition according to  claim 1  wherein the eighth subcell is comprised of Sc. 
     
     
         12 . A composition according to  claim 1  wherein the eighth subcell is comprised of La. 
     
     
         13 . A composition according to  claim 1  wherein the eighth subcell is comprised of Ce. 
     
     
         14 . A composition according to  claim 1  wherein the eighth subcell is comprised of Yb. 
     
     
         15 . A composition according to  claim 1  wherein the eighth subcell is comprised of Nd. 
     
     
         16 . A composition according to  claim 1  wherein the eighth subcell is comprised of Pd. 
     
     
         17 . A composition according to  claim 1  wherein the eighth subcell is comprised of Y. 
     
     
         18 - 20 . (canceled)