On the Soret effect in binary nonstoichiometric oxides—kinetic demixing of cuprite in a temperature gradient

Abstract

The Soret effect in nonstoichiometric copper(I)-oxide (cuprite, Cu 2Àd O) has been studied experimentally by means of non-isothermal solid state galvanic cells (thermocells) under different boundary conditions. At high temperatures and high oxygen activities, copper metal migrates down the temperature gradient and a gradient in the nonstoichiometry is established under stationary conditions. The heat of transport of copper metal is determined as Q* Cu c180 kJ/mol at a temperature of 1000 8C and at an oxygen activity of log a O 2 =À2.95. This result agrees with recent theoretical simulations of the heat of transport of atoms migrating via a vacancy mechanism. These predict a positive sign of the heat of transport and a considerably larger value than the activation energy for the atomic jumps. D

Potential thermoelectric performance of hole-doped Cu2O

“…High mobilities near 100 cm 2 V −1 s −1 at room temperature have been reported on Cu 2 O nanowires (> 95 cm 2 V −1 s −1 ) [60], polycrystalline thin films [61,62] and single crystals [63], but these are at a doping level far from those discussed here, and so can only be taken as indicating a possibility of high mobility. In combination with a lattice thermal conductivity of 4.5 W mK −1 [64] and our predicted room-temperature thermopower of 200 µV K −1 at this doping level, we can obtain a ZT value of ∼0.25. Considering the 1/T dependence of κ l and mobility, at 500 K κ l may be reduced to 2.7 W mK −1 , and the mobility should be 57 cm 2 V −1 s −1 according to the above assumed room-temperature mobility of 95 cm 2 V −1 s −1 .…”

Thermophoresis/diffusion as a plausible mechanism for unipolar resistive switching in metal–oxide–metal memristors

“…Equation (3) is similar to the one derived in Ref. [40] if one assumes Q * /R = U A /k B , where Q * is the heat of transport for oxygen vacancies and R is the ideal gas constant. In addition, Eqs.…”

“…In the spirit of the microscopic hopping model [12,26,40,49], we consider a one-dimensional billiard ball model with thermal, concentration and potential gradients and derive Eqs. (1)-(3) here to place them all on an equal footing.…”

Degradation of Functional Materials in Temperature Gradients - Thermodiffusion and the Soret Effect

“…(10) only by insertion of eq. (8) one obtains (17) which also forms the basis of Wagner's discussion of thermoelectric cells involving mixed conductors. 9) Both eqs.…”

“…Parallel to the different experimental studies a number of theoretical approaches towards an understanding of thermodiffusion by defects in solids have been put forward, as summarized by Allnatt and Chadwick. 1) In the past few years, only limited theoretical and experimental work has been reported, see e. g. Timm and Janek on the Soret effect in Cu 2-δ O 17) or Yoo and Hwang on thermodiffusion in yttria-stabilized zirconia. 18) With the current interest in high temperature thermoelectrics this may change.…”