Some magnetic properties of BaPrO3and BaTbO3: the magnetic form factor for Tb4+by neutron diffraction

The perovskites BaPrO 3 and BaTbO 3 containing octahedrally coordinated Pr 4+ (f 1 ) and Tb 4+ (f 7 ) have been studied by neutron diffraction and magnetic susceptibility measurements. BaPrO 3 remains paramagnetic from room temperature to 2K but BaTbO 3 becomes antiferromagnetic with simple G-type order at 37K. The Tb 4+ form factor has been determined by neutron diffraction experiments on a polycrystalline sample at 4.2K and is compared with the theoretical calculations for Gd 3+ and Eu 2+ , and experimental results for Gd 2 O 3 . An effective spin of 3.33+or-0.02 has been estimated for Tb 4+ .