Ionic conductivity of cold-pressed ceramics from grinding of R0.95M0.05F2.95 solid electrolytes (R = La,Nd; M = Ca,Sr, Ba) synthesized by reaction in melt

Cold-pressed ceramics of fluorine-conducting solid electrolytes La_{1 ? y} M _y F_{3 ? y} (M = Ca, Sr, Ba) and Nd_{1 ? y} Ca _y F_{3 ? y} with y = 0.95 have been synthesized in a melt of RF₃ (R = La, Nd) and MF₂ components in a fluorinating atmosphere and ground in a ball mill. The as-prepared ceramics require annealing, during which their porosity decreases and the conductivity is stably increased (by a factor of 250 for the R _{1 ? y} M _y F_{3 ? y} composition at 293 K). The Nd_0.95Ca_0.05F_2.95 and Nd_0.95Ca_0.05F_2.95 compositions have a maximum ionic conductivity σ(293 K) ～ 5 × 10^?6 Sm/cm. This value is larger (by a factor of about 10) than σ (293 K) for the R _{1 ? y} M _y F_{3 ? y} ceramics of tysonite phases prepared by mechanochemical synthesis with the cold pressing of reaction products.