Synthesis, Structure and Magnetic Properties of Monoclinic Lanthanum-Chromium Borate LaCr3(BO3)4

Single crystals of LaCr3(BO3)4 were synthesized through spontaneous nucleation from a K2Mo3O10 flux melt. The crystal structure was determined using single-crystal X-ray diffraction (XRD) at temperatures of 293K and 85K. LaCr-borate crystallizes in the monoclinic C2/c space group with unit cell parameters a = 7.47980(5) Å, b = 9.55180(7) Å, c = 11.48330(8) Å, β= 104.0060(6)°, V = 796.04(1) Å3 (for C1, T = 293K), and a = 7.47380(5) Å, b = 9.55520(7) Å, c = 11.47100(8) Å, β = 103.9330(6)°, V = 795.08(1) Å3 (for C2, T = 85K), each with Z = 4. The temperature dependence of the unit cell parameters, including the monoclinic angle (β) and the unit cell volume (V), was investigated over the range of 85 to 293K. No structural phase transitions were observed in the low-temperature region down to 85K. Differential scanning calorimetry (DSC) measurements revealed no high-temperature phase transitions between 50 and 1350°C. Infrared (IR) spectroscopy confirmed the monoclinic structure of LaCr3(BO3)4 crystals, revealing characteristic absorption bands, including the lowest frequency mode associated with the translational vibrations of the La3+ ion.