Flux growth and characterization of Ti- and Ni-doped enstatite single crystals

Single crystals of Ti- and Ni-doped enstatite MgSiO3 were grown by the slow-cooling flux growth method. Acidic oxides such as V2O5, MoO3 and lithium carbonate Li2CO3 were used as fluxes. The starting mixture was first held at 950 °C and then slowly cooled to 600 °C at a rate of 1.8 °C/h. Both Ti- and Ni-doped crystals were characterized and studied by stereo and polarized optical microscopy, powder crystal X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. Some crystals were further characterized by single-crystal X-ray diffraction, Fourier transform infrared and cathodoluminescence. Doped enstatite consists mainly of aggregations of single crystals, and other phases were also detected in variable amounts in all the runs. Transparent Ti-doped enstatite (1.5–0.2 mm in length) and green Ni-doped enstatite (0.6–0.2 mm in length) single crystals were euhedral in form and not homogeneous in width. The effects of growth parameters on yield and size of crystals are also discussed.

► Identification of the best conditions to obtain Ti- and Ni-doped enstatite.
► Presence of Ni and Ti in enstatite affects its size and chemical/physical properties.
► Spectra FT-IR of Ti-doped enstatite were very similar to that of Ni-doped enstatite.
► Ti-doped and Ni-doped enstatite were characterized by cathodoluminescence.