Structure, heat capacity and Raman spectra of Ba2MgWO6 single crystals grown in BaCl2-MgCl2 flux

We present a new method of Ba2MgWO6 single crystal synthesis that allows to grow larger crystals using a BaCl2 and MgCl2 flux. Difficulties to grow single crystals of a size suitable for macroscopic material property measurements caused the majority of characterisation being published on polycrystalline samples. Our single crystal diffraction and energy dispersive X-ray analysis confirmed high quality of synthesised samples. Heat capacity measurements from 300 K to 2 K do not show any phase transitions. However, Raman spectra measured down to 77 K contain additional weak peaks at all temperatures probed, which is in a contrast with only 4 Raman active modes expected from the crystal structure with the space group Fm3¯m. This calls for a more detailed study of potential symmetry breaking that could also influence the electronic properties of the material.