Electrochemistry of Na2SO4 (I) solid solutions with aliovalent cation substitution

Effect of Aliovalent Cation Doping on the Electrical Conductivity of Na2SO4: Role of Charge and Size of the Dopant

“…The difference in conductivity is minimal for the three compositions of Sr> (1.16 A s ), attributed to the possibility of a stronger binding between the impurities and vacancies. Our conductivity results for 2 m/o Sr> are in agreement with the reported values in Hofer et al (8).…”

“…11 (discussed clearly indicate that phase I is stabilized at 90°C. We also observe thermal peaks at temperatures between 275 and 290°C for the Sm>, Y>, and Nd>-doped compositions, suggesting the formation of some intermediate compounds, in agreement with reported data (8,16,17). For the 6 m/o dopant compositions, the sharp endotherm observed around 245°C (Table 2) for the Sr>-containing…”

“…Conductivity decreases with further increase in M (SO ) concentration because of the formation of impurity-vacancy clusters. (8), where conductivity peaks for a given vacancy concentration (7%) regardless of the charge, size, or type of dopant, is therefore unable to explain the observed results. In this regard, our results contradict the claim of Hofer et al (8) that the type of substituting cation does not matter.…”

“…Hofer et al (8) studied the conductivity behavior of Na SO (I) solid solutions formed by the aliovalent cations Zn>, Ni>, Sr>, and Y> and reported the presence of conductivity maxima at 7% vacancy concentration in all the solid solutions, irrespective of the size, charge, or nature of the substituting cations. Reports on the phase transition behavior and conductivity of Na SO -MgSO (9) and Na SO -CaSO (10) systems indicate an increase in conductivity only at high temperatures.…”

Electrical and thermal properties of Na2SO4 doped with NaVO3, Ln2(SO4)3 (Ln = Eu, Pr)

“…Furthermore, it is difficult to establish the SO2-SO, equilibrium rapidly at the surface of solid electrolytes. Attempts have often been made to increase the electrical conductivity of Na2S0, by doping with divalent or trivalent cations (25)(26)(27)(28)(29)(30). However, phase transformations still remain.…”