Growth, crystal structure, and properties of the Li3Ba2Ln3(MoO4)8 (Ln = Er, Tm) molybdates

International audienceThe compounds Li3Ba2Ln3(MoO4)8 (Ln = Er, Tm) have been obtained by the high-temperature flux technique using the slow cooling method. Crystals grown spontaneously were used to characterize the materials and investigate their properties using X-ray diffraction (XRD), Raman spectroscopy, and magnetic measurements. Single crystal structures were solved and refined in the monoclinic space group C2/c. Lattice dimensions are a = 5.1935, b = 12.6364, c = 19.1022 Å, = 91.399 ° for Er-based triple molybdate (pink crystals) and a = 5.1846, b = 12.5766, c = 19.1557 Å, = 91.525 ° for Tm-molybdate (green crystals). The Ln cations, mainly at general position 8f, are coordinated by eight oxygen atoms and adopt a distorted antiprismatic geometry. The distribution of atoms over the three cationic sites is discussed comparatively to literature reports. Unpolarized Raman characterization supports both the disordered cation distribution, and the distortion of the MoO4 units. From the magnetic susceptibility measurements, it is found that the two triple molybdates follow a Curie-Weiss law in the 10-300 K domain, with a negative paramagnetic temperature θCW. The antiferromagnetic character is highlighted by the field-dependent magnetization curves