Electrical Conductivity and Phase Transformation Studies on Pure and Doped (Mg²⁺, Zn²⁺, Cu²⁺, and Mn²⁺) Crystals of K₂SO₄

Abstract

MAHADEVA NATARAJAN and ETALO A. SECCO. Can. J. Chem. 53,1542 (1975. . , Electrical conductivity measurements have been made on single crystals of undoped potassium sulfate and on single crystals of K2S04 doped with divalent ions, viz. MgZ+, Zn2+, Cu2+, and MnZ+. The presence of the divalent ion increases the cation migration energy. The lower defect formation energy is attributed to the lower symmetry of K2S04 relative to the high symmetry cubic systems previously studied.The presence of the dopants and dopant concentration, i.e. Cu2+, show varying effects on the magnitude and nature of the conductivity discontinuity at the orthorhombic-hexagonal phase transition temperature. The phenomenon of "pretransition", 350 to 425 "C, is observed in both pure and doped crystals. Preannealing the crystal contributes to interesting behavior on all the crystals studied. The G-T behavior of K2S04 crystal doped with radioactive "Zn, however, exhibits a simpler linear dependence and the absence of "pretransition" anomaly. MAHADEVA NATARAJAN et ETALO

Potassium ion conductivity of KNO2 mixed oxides

“…One of the other K + ion conductors is polycrystalline potassium sulfate (K 2 SO 4 ). However, the K + ion conductivity of K 2 SO 4 polycrystal is as small as 3.38 × 10 −5 S cm −1 at 600 • C [2] and still three orders of magnitude lower than that of the practical application region (>10 −2 S cm −1 ) of the representative Li + and Na + ion conducting solids. In order to obtain practical K + ion conductors, the realization of polycrystalline K + ion conducting solid showing the ion conductivity which enters into the application region, is highly requested.…”

“…K + ion is one of conducting ion species in solids [1,2]. However, the K + ion (ionic radius (four-coordinate): 0.137 nm) conductivity is appreciably below the practical application region compared with those of Li + (ionic radius (four-coordinate): 0.059 nm) and Na + (ionic radius (four-coordinate): 0.099 nm) ion conductors, such as Li + ion super ionic conductor of LISICON [3] and Na + ion super ionic conductor of NASICON [4], according to its relatively large ionic size.…”

“…The temperature dependencies of the conductivity for the 0.595Gd 2 O 3 -0.405KNO 3 solid solution (᭹) and 0.4KNO 2 mixed 0.6Nb 2 O 5 ( ) with the corresponding data of K + -␤ -Al 2 O 3 single crystal[5] (in ab plane) (solid line) and polycrystalline K 2 SO 4[2] (dotted line).…”

New type of potassium ion conducting solid based on lanthanum oxysulfate

“…Furthermore, the K + ion conductivity drastically reduced below 350 • C. Potassium sulfate (K 2 SO 4 ) has also been reported as a polycrystalline solid electrolyte in which the K + ion conducts above 650 • C [7,8]. However, the K + ion conductivity of K 2 SO 4 is several orders of magnitude below the application range of σ > 10 −2 S cm −1 .…”

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.…”