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(αβ0)00 with lattice constants a = 5.30284(4), b = 5.32699(3), c = 11.7935(1) Å, γ = 90.163(1)°, and the modulation vector q = 2/3a* + 0.88810(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 3P0 → 3F2 transition. Magnetic susceptibility measurements reveal Curie−Weiss paramagnetism with predominating antiferromagnetic interactions between Pr3+-magnetic moments and no evidence of magnetic transitions down to T = 5 K.