Electrical conductivity and thermoelectric power of liquid selenium doped with thallium and indium

The temperature dependence of the electrical conductivity and thermoelectric power of liquid selenium with thallium and indium additives have been studied. Large variations appear in the electrical conductivity and thermoelectric power, where Tl and In additives favourp-type conduction.     

Electrical conductivity,thermoelectric power and figure of merit of doped Bi-Sb tapes produced by melt spinning technique

Temperature dependence of electrical conductivity and thermoelectric power are presented for In and Pb doped Bi + 8.28 at % Sb quenched tapes between 77 and 300K. The results are explained in terms of model for disordered semiconductors. Analysis of our data on electrical conductivity indicates the presence of a temperature independent part and a strongly temperature dependent part. While theT independent part originates from band conduction, theT dependent component could be understood considering the presence of localized states. Thermoelectric figure-of-merit of these tapes are also measured at 300K, which shows a large enhancement (∼40%) over that reported earlier on thin Bi-Sb films. This suggests that doped Bi-Sb quenched tapes may be considered as a candidate for material in producing economic and light weight thermoelectric devices.     

Electrical properties of CdSb single crystals doped with silver

A study is made of the electrical and thermoelectrical properties of CdSb single crystals weakly and heavily doped with silver. The electrical conductivity, the Hall effect and the thermoelectric force in intrinsic conduction are studied on samples of CdSb oriented in the direction of the crystal-lographic axisb. The activation energy of the acceptors is determined as well as the density of states effective mass and their dependence on the temperature and concentration, and the mobility of holes is studied.     

Electrical conductivity and thermoelectric power of AgInSe2 in the solid and liquid states

The electrical conductivity and thermoelectric power of AgInSe₂ have been investigated as a function of temperature from 420°C to 950°C. Experimental data are analyzed in terms of a model developed for the density of states and electrical transport in solid amorphous semiconductors [1]. The activation energy calculated from electrical conductivity data is found to be 0.06 eV for the solid and 0.37 eV for the liquid phase. Moreover, the coefficient of the linear decrease of the energy gap with temperature was found to be 1.96×10^–4 eV/K.     

Electrical conductivity and thermoelectric emf of nickel and molybdenum films

The effect of surface and grain-boundary scattering of the current carriers on the electrical conductivity and absolute differential thermoelectric emf of nickel and molybdenum films is investigated. The experiments were carried out under superhigh-vacuum conditions (P<10^–7 Pa) in sealed-off glass vessels. The results of the experiment are processed using the Mayadas-Shatzkes and Telet-Tasser-Pichard model representations. The charge-transfer parameters in the films along electron and hole trajectories are determined.Iv. Franko L'vov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 33–37, December, 1992.     

Electrical conductivity of doped and undoped calcium tartrate

The electrical conductivity of polycrystalline samples of calcium tartrate tetrahydrate ([CaC₄H₄O₆ 2H₂O] 2H₂O) in pure form and doped with barium and with strontium were studied in the temperature range (65<T<95°C). According to these results, it seems that two types of conduction exist in these compounds, one at low temperature and the other at high temperature, by the way of extrinsic and intrinsic conduction, respectively. This behavior may be attributed to the rotation of the tartrate ions by thermal energy.     

Electrical conductivity of Co doped cuprous oxide

The solubility limit of metals in cuprous oxide is very low and it is therefore difficult to form solid solutions of metal oxides with cuprous oxide. In an on going research looking for such solid solutions and their properties we have prepared Co doped Cu₂O. We report here on measurements of the electrical conductivity of Co doped Cu₂O as a function of the oxygen partial pressure. It is found that Co doped material is an n-type semiconductor in the low oxygen partial pressure regime and p-type at higher oxygen pressures (while undoped Cu₂O is a p-type material throughout the whole existence regime). A point defect model is discussed. The ionic transference number is also measured and is found to be less than 2⋅10⁻⁴. Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995     

The thermoelectric efficiency of CdSb and solid solutions of Zn x Cd1−x Sb with hole conductivity

Based on the study of transport effects in CdSb single crystals and solid solutions of ZnSb-CdSb with hole conductivity, an analysis of the thermoelectric conversion efficiency is made. The parameters, experimentally determined over a wide temperature range, are compared to the transport coefficients of a highly doped CdSb and solid solution of Zn_0.2Cd_0.8Sb.     

Electrical conductivity of pure and doped α-ferric oxides

Electrical conductivities of αFe₂O₃ containing 1 2, 2 3 and 3 8 mol% CdO were measured in the temperature range of 300 to 1300°C at Po₂'s of 10^?9 to 10^?1 atm Plots of log $\text{σ}\text{vs}\text{1}\text{T}$ at constant Po₂'s were found to be linear with an inflection at temperatures around 500°C and higher Po₂'s than 1 × 10^?4 atm. The activation energies obtained by the least-squares method were 1 34 eV for the intrinsic region and 0 51 eV for the extrinsic region on αFe₂O₃ doped with 38 mol% CdO The extrinsic conductivities disappeared at lower Po₂'s than 1 × 10^-4atm, and the intrinsic conduction appeared on the specimens investigated The electrical conductivities decreased with increasing amount of CdO doping The predominant defects in this system are believed to be interstitial Fe² for the intrinsic region and oxygen vacancies for the extrinsic region.     

Magnetic properties of CdSb doped with Ni

Magnetic properties of the group II–V semiconductor CdSb single crystals doped with Ni (2 at%) are investigated. Deviation of the zero-field-cooled susceptibility, χ_ZFC, from the field-cooled susceptibility is observed below 300 K, along with a broad maximum of χ_ZFC (T) at T_b in fields below the anisotropy field B_K∼4 kG. T_b(B) obeys the law [T_b(B)/T_b(0)]^1/2=1–B/B_K with T_b(0)∼100 K. The magnetization exhibits saturation above ∼20–30 kG, a weak temperature dependence and anisotropy of the saturation value M_s. The coercive field is much smaller then B_K and displays anisotropy inverted with respect to that of M_s. Such magnetic behavior is expected for spheroidal Ni-rich Ni_1−xSb_x nanoparticles with high aspect ratio, broad distribution of the sizes and with orientations of the major axis distributed around a preferred direction.     

Electrical conductivity and dielectric properties of sulfamic acid doped polyaniline

The temperature and frequency dependence of dielectric constant (ε′) and dielectric loss (ε″) is studied for different samples of polyaniline (PANI), doped with different concentration of sulfamic acid in the frequency range (10–100 kHz) and temperature range (300–400 K). The dc conductivity has also been measured to see the effect of sulfamic acid and the conduction mechanism has been explained by the propagation of polaron through a conjugated polymer chain due to shifting of double bonds (alternation), which gives rise to electrical conduction.     

Electrical conductivity,thermoelectric power and hall effect in p-type molybdenite (MoS2) crystal

Principal electrical conductivities and seebeck coefficients, as well as Hall effect, in p-type single crystals of natural molybdenite (MoS₂) have been investigated within the temperature range 100°K to 850°K. The results have been discussed and the values of different parameters of the charge carriers obtained.     

Variations in thermoelectric power of thin monocrystalline films with conductivity

Starting from the bi-dimensional model for grain boundaries in monocrystalline thin films, the difference in thermoelectric power is expressed in terms of conductivity and energy dependence of the bulk electronic mean free pathU. A new procedure is suggested for measuringU.     

Simple theoretical analysis of the thermoelectric power in quantum dot superlattices of non-parabolic heavily doped semiconductors with graded interfaces under strong magnetic field

We study theoretically the thermoelectric power in the presence of a large magnetic field (TPM) in heavily doped III–V, II–VI, PbTe/PbSnTe, strained layer and HgTe/CdTe quantum dot superlattices (QDSLs) with graded structures on the basis of newly formulated electron energy spectra and compare the same with that of the constituent materials. It has been found, taking heavily doped GaAs/Ga_1−xAl_xAs, CdS/CdTe, PbTe/PbSnTe, InAs/GaSb and HgTe/CdTe QDSLs as examples, that the TPM increases with increasing inverse electron concentration and film thickness, respectively, in different oscillatory manners and the nature of oscillations is totally band structure dependent. We have also suggested the experimental methods of determining the Einstein relation for the diffusivity–mobility ratio, the Debye screening length and the electronic contribution to the elastic constants for materials having arbitrary dispersion laws.     

Electrical conductivity and complex electric modulus of titanium doped nickel-zinc ferrites

The samples Ni_1+x−yZn_yTi_x Fe_2−2xO₄; y=0.1, 0.0≤x≤0.5 were prepared in a single-phase spinel structure as indicated from X-ray analysis. Electrical conductivity and dielectric measurements at different temperatures from 300 K to 600 K in the frequency range from 42 Hz to 5 MHz have been analyzed. The relation of conductivity with temperature revealed a semiconductor to semimetallic behavior as Ti⁴⁺ concentration increases. The conduction mechanism depends mainly on the valence exchange between the different metal ions in the same site or in different sites. The dielectric constant as a function of temperature and frequency showed that there is a strong dependence on the compositional parameter x. The electrical modulus has been employed to study the relaxation dynamics of charge carriers. The result indicates the presence of correlation between motions of mobile ion charges. The activation energies extracted from M′(ω) and M″(ω) peaks are found to follow the Arrhenius law. The electrical conductance of the samples found to be dependent on the temperature and frequency.     

Thermal conductivity of high-porosity heavily doped biomorphic silicon carbide prepared from sapele wood biocarbon

The electrical resistivity and thermal conductivity of high-porosity (～52 vol %, channel-type pores) bio-SiC samples prepared from sapele wood biocarbon templates have been measured in the temperature range 5–300 K. An analysis has been made of the obtained results in comparison with the data for bio-SiC samples based on beech and eucalyptus, as well as for polycrystalline β-SiC. The conclusion has been drawn that the electrical resistivity and thermal conductivity of bio-SiC samples based on natural wood are typical of heavily doped polycrystalline β-SiC.     

Investigations on thermoelectric power of lanthanum oxide doped ferroelectric sodium vanadate

The thermoelectric power of ferroelectric sodium vanadate doped with different concentrations of lanthanum oxide has been measured in the temperature range covering their transition temperatures. It has been observed that the thermoelectric power increases with temperature, attains maximum value and with further increase in the temperature decreases to zero, indicating Curie temperature of the respective samples; however, it changes the sign for higher temperature. The thermoelectric power of sodium vanadate increases to maximum with increase in doping concentration of lanthanum oxide from 0.025 to 0.1 mol%; however, it decreases for higher concentrations. Pure as well as lanthanum oxide doped sodium vanadate samples showp-type behaviour in the ferroelectric region andn-type behaviour in the paraelectric region.