Method for producing a thermoelectric intermetallic compound

Abstract

A method for producing an intermetallic compound, the method comprising: (1) providing components A, B and X; and forming by solid state reaction of components A, B and X an intermetallic compound having a filled skutterudite structure and formula of A a B b X c ; (2) melting the intermetallic compound having a filled skutterudite structure produced in step (1) in the presence of additional X; and (3) annealing the intermetallic compound of step (2) in the presence of additional X at a temperature equal to, or greater than the phase formation temperature of the intermetallic compound.

1 . A method for producing an intermetallic compound, the method comprising:
 (1) providing components A, B and X, wherein A, B and X are:
 A is selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Yb, In, Ca, Sr, Ba and Tl, and mixtures of two or more thereof; 
 B is selected from one or more transition metal atoms; and 
 X is selected from one or more Group IIIA-VIIA atoms; 
   
       and forming by solid state reaction of components A, B and X an intermetallic compound having a filled skutterudite structure and formula of
   A a B b X c    
 
       wherein A, B and X are as defined above and 
       a is the sum of all A atoms wherein 0<a≦1 
       b is the sum of all B atoms wherein 3.5≦b≦4; and 
       c is the sum of all X atoms wherein 8≦c≦12;
 (2) melting the intermetallic compound having a filled skutterudite structure produced in step (1) in the presence of additional X; and 
 (3) annealing the intermetallic compound of step (2) in the presence of additional X at a temperature equal to, or greater than the phase formation temperature of the intermetallic compound. 
 
     
     
         2 . The method according to  claim 1  wherein A, B and X are provided in stoichiometric amounts. 
     
     
         3 . The method according to  claim 1  wherein the solid state reaction of A, B and X to form the intermetallic compound having a filled skutterudite structure and a formula of A a B b X c  is carried out by heating at a temperature range of from 500° C. to 900° C. for from 1 to 7 days. 
     
     
         4 . The method according to  claim 1  wherein the intermetallic compound is melted using an arc and/or induction melter. 
     
     
         5 . The method according to  claim 1 , further comprising a step of pelletising the intermetallic compound provided in step (1) before the melting step (2). 
     
     
         6 . The method according to  claim 1 , wherein the annealing step (3) is performed for a duration greater than 24 hours. 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . The method according to  claim 1 , wherein A is selected from the rare earth elements and mixtures of two or more thereof. 
     
     
         10 . (canceled) 
     
     
         11 . The method according to  claim 1  wherein B is selected Fe, Co, Rh, Ru, Os and Ir. 
     
     
         12 . (canceled) 
     
     
         13 . The method according to  claim 1  wherein X is selected from C, Si, Ge, Sn, Pb, N, P, As, Sb, Bi, S, Se and Te. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The method according to  claim 1  wherein a is in the range of from 0.5 to 1. 
     
     
         17 . (canceled) 
     
     
         18 . The method according to  claim 1  wherein b is 4 and/or wherein c is 12. 
     
     
         19 . (canceled) 
     
     
         20 . An intermetallic compound obtainable by the method of  claim 1 . 
     
     
         21 . An intermetallic compound exhibiting a ZT 600 k  value of ≧0.9 obtainable by the method of  claim 1 . 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . An intermetallic compound exhibiting a ZT 600 k  value of ≧0.9 and having the formula:
   A′ a′ B′ b′ X′ c′ 
 
 
       wherein,
 A′ is selected from at least two of La, Ce, Pr, Nd, Pm, Sm, Eu, Yb, Ca, Sr, Ba and Tl, and mixtures of three or more thereof; 
 B′ is selected from one or more transition metal atoms; 
 X′ is selected from one or more Group IIIA-VIIA atoms; 
 a′ is the sum of all A′ atoms wherein 0<a′≦1 
 b′ is the sum of all B′ atoms wherein 3.5≦b′≦4; and 
 c′ is the sum of all X′ atoms wherein 10≦c′≦12. 
 
     
     
         25 . An intermetallic compound according to  claim 24  having a filled skutterudite structure. 
     
     
         26 . An intermetallic compound according to  claim 24  wherein A′ is selected at least two rare earth elements and mixtures of three or more thereof. 
     
     
         27 . (canceled) 
     
     
         28 . An intermetallic compound according to  claim 24  wherein B′ is selected Fe, Co, Rh, Ru, Os and Ir. 
     
     
         29 . (canceled) 
     
     
         30 . An intermetallic compound according to  claim 24  wherein X′ is selected from C, Si, Ge, Sn, Pb, N, P, As, Sb, Bi, S, Se and Te. 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . An intermetallic compound according to  claim 24  wherein a′ is in the range of from 0.5 to 1. 
     
     
         34 . (canceled) 
     
     
         35 . An intermetallic compound according to  claim 24  wherein b′ is 4 and/or wherein c′ is 12. 
     
     
         36 . (canceled) 
     
     
         37 . An intermetallic compound according to  claim 24  exhibiting a ZT 600 k  value of ≧1. 
     
     
         38 . (canceled) 
     
     
         39 . (canceled) 
     
     
         40 . A peltier cooler, a thermoelectric generator or a magnetoresistor comprising an intermetallic compound as defined in  claim 24 . 
     
     
         41 . (canceled) 
     
     
         42 . (canceled) 
     
     
         43 . The use of an intermetallic compound as defined in  claim 24  as a thermoelectric material. 
     
     
         44 . A multilayer comprising a first electrode, a second electrode, and an interlayer there between, said interlayer comprising an intermetallic compound as defined in  claim 24 .