Crystal, electronic structures, optical and magnetic properties of Tb(4)Al(2)O(9)

The crystal and electronic structures, optical and magnetic properties of Tb(4)Al(2)O(9) have been reported. Polycrystalline Tb(4)Al(2)O(9) was synthesized by a solid state method at 1600 'C for 4 h under N(2) atmosphere (0.48 MPa) using AlN as an in situ reducing agent. Tb(4)Al(2)O(9) is crystallized in the monoclinic crystal system having space group P2(1)/c with a = 0.74831(1) nm, b = 1.05569(1) nm, c = 1.11507(1) nm, b = 108.96(1)(0). Tb(4)Al(2)O(9) was calculated to be a wide band gap semiconductor with indirect band gap energy of about 3.83 eV in fair agreement with the experimental value [not, vert, similar]4.59 eV obtained from the diffuse reflection spectrum. No photoluminescence of Tb(3+) could be observed because of large effects of photoionization and concentration quenching of Tb(3+) in Tb(4)Al(2)O(9). Tb(4)Al(2)O(9) exhibited weak antiferromagnetic interactions with an effective magnetic moment of near that of the Tb(3+) free ion.