Synthesis, structures, and magnetic properties of ternary rare earth oxides ALnO 2 (A = Cu or Ag; Ln = rare earths) have been investigated. CuLnO 2 (Ln = La, Pr, Nd, Sm, Eu) were synthesized by the direct solid state reaction of Cu 2 O and Ln 2 O 3 , and AgLnO 2 (Ln = Tm, Yb, Lu) were obtained by the cation-exchange reaction of NaLnO 2 and AgNO 3 in a KNO 3 flux.These compounds crystallized in the delafossite-type structure with the rhombohedral 3R type (space group: R-3m). Magnetic susceptibility measurements showed that these compounds are paramagnetic down to 1.8 K. Specific heat measurements down to 0.4 K indicated that CuNdO 2 ordered antiferromagnetically at 0.8 K.3

Hydraulic conductivities were determined for compacted Fe(III)-montmorillonite sample. The Fe(III)-montmorillonite sample used in this study, which was prepared by the ion-exchange treatment of Namontmorillonite in FeCl 3 solution, contains less than 20% of Na þ ions as exchangeable cations and negligibly small amounts of iron precipitates. The measured hydraulic conductivities of compacted Fe(III)-montmorillonite were determined to be the order of 10 À9 , 10 À11 , and 10 À13 m s À1 at dry densities of 0.80, 1.01, and 1.20 Mg m À3 , respectively. These values were found to be kept constant during the experimental period, suggesting no significant change in the physicochemical properties of Fe(III)-montmorillonite during the experiment. When compared with Na-montmorillonite, remarkably high values of hydraulic conductivities were found for Fe(III)-montmorillonite at the dry densities of 0.8 and 1.0 Mg m À3 . On the other hand, almost the same value of hydraulic conductivity was obtained at the dry density around 1.2 Mg m À3 . This different effect of exchangeable cations on the hydraulic conductivity of montmorillonite could be attributed to the different sizes of macropores in compacted montmorillonite and/or the different thicknesses of electrical double layers formed over montmorillonite sheets.

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