Thermoelectric material and thermoelectric device

A thermoelectric material comprising a composition represented by the following formula (B):

• (Lnd(Tia2Zrb2Hfc2)1-d)xNiySn100-x-y (B)
• where Ln is at least one element selected from the group consisting of Y and rare earth elements, and 0<a2<1, 0<b2<1, 0<c2<1, a2+b2+c2=1, 30≦x≦35, and 30≦y≦35,
• wherein the composition has at least two MgAgAs crystal phases different in a lattice constant, and,
• assuming that X-ray diffraction peak intensity from a (422) diffraction plane of a first MgAgAs crystal phase having a smallest lattice constant and X-ray diffraction peak intensity from a (422) diffraction plane of a second MgAgAs crystal phase having a largest lattice constant be I1 and I2, respectively, a value of I1/(I1+I2) being in a range of 0.2 to 0.8.

A thermoelectric material comprising a composition represented by the following formula (A):

• (Tia1Zrb1Hfc1)NiySn100-x-y (A)
• wherein 0<a1<1, 0<b1<1, 0<c1<1, a1+b1+c1=1, 30≦x≦35, and 30≦y≦35,
• wherein the composition has at least two MgAgAs crystal phases different in a lattice constant, and
• wherein assuming that an X-ray diffraction peak intensity from a (422) diffraction plane of a first MgAgAs crystal phase having a smallest lattice constant and an X-ray diffraction peak intensity from a (422) diffraction plane of a second MgAgAs crystal phase having a largest lattice constant are I1 and I2, respectively, then the thermoelectric material has a value of I1/(I1+I2) in a range of 0.2 to 0.8 and a ZT value of higher than 1.3, wherein Z=α2/(ρκ) where α is a Seebeck coefficient of thermoelectric material, ρ is an electrical resistivity of the thermoelectric material, κ is a thermal conductivity of the thermoelectric material, and T is an absolute temperature.

A thermoelectric material comprising a composition represented by the following formula (B):

• (Lnd(Tia2Zrb2Hfc2)1-d)xNiySn100-x-y (B)
• wherein Ln is at least one element selected from the group consisting of Y and rare earth elements, and 0<a2<1, 0<b2<1, 0<c2<1, a2+b2+c2=1, 30≦x≦35, and 30≦y≦35,
• wherein the composition has at least two MgAgAs crystal phases different in a lattice constant, and
• wherein assuming that an X-ray diffraction peak intensity from a (422) diffraction plane of a first MgAgAs crystal phase having a smallest lattice constant and an X-ray diffraction peak intensity from a (422) diffraction plane of a second MgAgAs crystal phase having a largest lattice constant are I1 and I2, respectively, then the thermoelectric material has a value of I1/(I1+I2) in a range of 0.2 to 0.8 and a ZT value of higher than 1.3, wherein Z=a2/(ρκ) where α is a Seebeck coefficient of thermoelectric material, ρ is an electrical resistivity of the thermoelectric material, κ is a thermal conductivity of the thermoelectric material, and T is an absolute temperature.