Crystal Structure and Optical and Magnetic Properties of Pr2(MoO4)3

Praseodymium molybdate Pr2(MoO4)3 was synthesized using the standard ceramic route. The crystal structure of the material has been successfully solved in superspace group I2/b(Rβ0)00 with lattice constants a = 5.30284(4), b = 5.32699(3), c = 11.7935(1)A° , γ = 90.163(1) , and the modulation vector q = 2/3aþ0.88810(2)b. The deviation of the q vector from a rational value allows a description of the structure in terms of nanosize domains with the La2(MoO4)3-like structure separated by stacking faults. Under 450 nm excitation, (3P0 level) Pr2(MoO4)3 exhibits the characteristic red emission, with the most intense band at 649 nm corresponding to a $^3P_0\rightarrow^3F_2$ transition. Magnetic susceptibility measurements reveal Curie-Weiss paramagnetism with predominating antiferromagnetic interactions between $Pr^{3+}$-magnetic moments and no evidence of magnetic transitions down to T = 5 K.