We report magnetisation, conductivity and structural data on the Ruddl
esden-Popper Mn-III/Mn-IV oxides LnSr(2)Mn(2)O(7) (Ln = La, Tb); while
LaSr2Mn2O7 undergoes an insulator-metal transition and an increase in
spontaneous magnetisation at 132 K, the isostructural terbium compoun
d is semiconducting and paramagnetic throughout the range 4.2 < T/K <
300.