Electrical Resistivity and Thermoelectric Power of Intercalation Compounds M_xTiS₂ (M = Mn, Fe, Co, and Ni)

Abstract

The temperature dependence of electrical resistivity and thermoelectric power of the intercalation compounds of M,TiS, (M = Mn, Fe, Co, and Ni; 0 z 5 1/3) with layered structures are measured over the temperature range 1.5 to 300 K. These experimental results can be explained by a simple model, which takes into account a temperature-independent residual term and intra-and intervalley scattering by acoustic phonons. It is also shown that a phonon drag effect is effective for the thermopower. The effect of intercalation of 3d metals into TiS, layers on the electronic properties is discussed.Die Temperaturabhangigkeit des elektrischen Widerstands und der Thermospannung der Interkalate von M,TiS, (M = Mn, Fe, Co, und Ni; 0 5 x 5 1/3) mit Schichtstrukturen werden bei Temperaturen von 1,5 bis 300 K gemessen. Die experimentellen Ergebnisse konnen durch ein einfaches Modell erklart werden, das einen temperaturunabhangigen Restterm sowie ,,intra-und intervalley scattering" durch akustische Phononen berucksichtigt. Es wird auch gezeigt, daB ein ,,phonon-drag"-Effekt fur die Thermospannung wirksam ist. Der EinfluB der Interkalation von 3d-Metallen in die TiS,-Schichten auf die elektronischen Eigenschaften wird diskutiert.

Pressure Dependence of Electrical Resistivity in Intercalation Compounds MxTiS2 (M = 3d Transition Metal)

“…The positive sign of y means that the intervalley scattering via electron--LA phonon interactions is enhanced by applied pressure. Furthermore, we note that the value of y is strongly dependent on the guest 3d metal, which may suggest that the Fermi surface of M,TiS, is pressure-dependent, as pointed out previously [13]. I n conclusion, the pressure dependence of the electrical resistivities of TiS, and M,TiS, is reasonably explained by taking account of the pressure variations of the residual resistivity, the temperature-dependent intra-and intervalley scattering terms.…”

“…As shown previously [13], the resistivity e of TiS, and M,TiS, is reasonably expressed by the sum of three terms, e = e o + e l + e 2 , The best-fit parameters ,oo, B , R, and 8D for each sample, together with those for other intercalates, are given in Table 1. The Debye temperature is almost pressureindependent, as expected.…”

Strain-induced electronic phase transition and strong enhancement of thermopower ofTiS2

“…Previous experimental studies [12] have reported that nearly stoichiometric TiS 2 shows a large power factor value of 37.1 µW/K 2 -cm at room temperature that is comparable with the best thermoelectric material Bi 2 Te 3 [13]. The large power factor originates from a sharp increase in the density of states just above the Fermi energy as well as the inter-valley scattering of charge carriers [12,14,15]. However, the semimetallic nature of TiS 2 gives rise to bipolar effects which are not desirable for thermoelectric applications [16].…”

Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides

“…( a ) Seebeck coefficient ( S ); ( b ) electrical resistivity (ρ); and ( c ) power factor ( S 2 /ρ) plotted against the carrier concentration ( n ) at 300 K in the in-plane ( ab -plane) direction for Ti 1+ x S 2 [29,30,41,43,44,75,76,77]. The solid line in ( a ) represents the values calculated using Equation (4) with m * / m 0 ( m 0 is the free electron mass) equal to 2.88 when n is greater than 5 × 10 20 cm − 3 [74,75,76].…”

“…The solid line in ( a ) represents the values calculated using Equation (4) with m * / m 0 ( m 0 is the free electron mass) equal to 2.88 when n is greater than 5 × 10 20 cm − 3 [74,75,76]. …”