The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, th...The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, the electrical conductivity, Seebeck coefficient and figure of merit are calculated by using Boltzmann transport theory, further eval- uated as a function of carrier concentration. We find that the Seebeck coefficient is more anisotropic than electrical conductivity. The figure of merit of BaSi2 is predicted to be quite high at room temperature, implying that optimal doping may be an effective way to improve thermoelectric properties.展开更多
The thermoelectric performances of 1 T-ZrX_2(X=S and Se) single layers were investigated using a combination of density functional calculations and semi-classical Boltzmann transport theory. Because of the high hole m...The thermoelectric performances of 1 T-ZrX_2(X=S and Se) single layers were investigated using a combination of density functional calculations and semi-classical Boltzmann transport theory. Because of the high hole mobilities at 300 K, ultrahigh power factors(PF = S^2σ) were found in the P-type compounds;these values were ~ 11.95 and ~13.58 mWK ~2 m^1 for 1T-ZrS_2 and 1T-ZrSe_2 single layers, respectively.However, because of the Lorenz relation between the electrical conductivity(σ) and an electron's thermal conductivity(K_(el)) given by the Wiedemann-Franz law, the electronic figures of merit(Z_(el)T = PF T/K_(el)) at 300 K were approximately 0.67 and 0.75 for the N-and P-type 1T-ZrSe_2, respectively. In addition, the lattice thermal conductivities(K_(Ph)) were calculated, giving values of ~1.43 and ~0.97 W K ~1 m^1 for 1T-ZrS_2 and 1T-ZrSe_2 single layers, respectively. Therefore, because of the lower K_(Ph)/K_(el) ratio, the P-type 1T-ZrX_2 single layers possess higher fngure-of-merits(ZT = Z_(el)T/(1+(K_(Ph)/K_(el))) than their counterparts. This signifies that the P-type samples demonstrate better thermoelectric performance than the N-type ones. The thermoelectric properties of metastable 2H-ZrX_2(X = S and Se) single layers were also investigated.展开更多
基金supported by the National Basic Research Program of China (Grant No.2007CB607504)Graduate Independent Innovation Foundation of Shandong University (Grant No.yzc09076)
文摘The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2. With the constant relaxation time and rigid band approximation, the electrical conductivity, Seebeck coefficient and figure of merit are calculated by using Boltzmann transport theory, further eval- uated as a function of carrier concentration. We find that the Seebeck coefficient is more anisotropic than electrical conductivity. The figure of merit of BaSi2 is predicted to be quite high at room temperature, implying that optimal doping may be an effective way to improve thermoelectric properties.
基金supported by the National Natural Science Foundation of China (61704044, 51606192, and 51372064)Natural Science Foundation of Hebei Province (A2017201219)+2 种基金CAS Pioneer Hundred Talents Programsupported by the High-Performance Computing Center of Hebei Universitythe Institute of Engineering Thermophysics,CAS
文摘The thermoelectric performances of 1 T-ZrX_2(X=S and Se) single layers were investigated using a combination of density functional calculations and semi-classical Boltzmann transport theory. Because of the high hole mobilities at 300 K, ultrahigh power factors(PF = S^2σ) were found in the P-type compounds;these values were ~ 11.95 and ~13.58 mWK ~2 m^1 for 1T-ZrS_2 and 1T-ZrSe_2 single layers, respectively.However, because of the Lorenz relation between the electrical conductivity(σ) and an electron's thermal conductivity(K_(el)) given by the Wiedemann-Franz law, the electronic figures of merit(Z_(el)T = PF T/K_(el)) at 300 K were approximately 0.67 and 0.75 for the N-and P-type 1T-ZrSe_2, respectively. In addition, the lattice thermal conductivities(K_(Ph)) were calculated, giving values of ~1.43 and ~0.97 W K ~1 m^1 for 1T-ZrS_2 and 1T-ZrSe_2 single layers, respectively. Therefore, because of the lower K_(Ph)/K_(el) ratio, the P-type 1T-ZrX_2 single layers possess higher fngure-of-merits(ZT = Z_(el)T/(1+(K_(Ph)/K_(el))) than their counterparts. This signifies that the P-type samples demonstrate better thermoelectric performance than the N-type ones. The thermoelectric properties of metastable 2H-ZrX_2(X = S and Se) single layers were also investigated.
