Complete Documentation of All the Mass/Charge Transport Properties of La2NiO4+δ and Its Puzzling Thermomigration Behavior

All the mass/charge transport properties of mixed conductingLa(2)NiO(4+& delta;), with oxide ions O2- (= i) and holes h(+) (= h) as the mobile charged components,may be exhaustively documented succinctly in terms of a 2 x 3coupling coefficient matrix L of the Onsagerian causalitybetween the fluxes of the mobile components, J ( k ) (k = i, h) and their drivingforces, electrochemical potential gradients backward difference & eta;( k ) (k = i, h) and temperature gradient backward difference T. In this work, we introduce the simplest-ever rugged thermocellto measure the "non-isothermal" transport properties{L (iT ), L (hT )} of La2NiO4+& delta; across its entire stability range at elevated temperatures of 800,900, and 1000 & DEG;C, respectively. We then complete documentationof all the mass/charge transport properties L ofthe system La2NiO4+& delta; by combining withits "isothermal" transport properties {L (ii), L (ih), L (hi), and L (hh)} reported earlier(Kim, H.-S.; Yoo, H.-I. Phys. Chem. Chem. Phys. 2011, 13, 4651). Finally, we discuss itspuzzling thermomigration behavior (L ( kT )), with the mobile component O being rendered fromthermophilic (J (O) & PROP; backward difference T) to thermophobic (J (O) & PROP;- backward difference T) with increasing T and & delta;.