The observation of ferroelastic/ferroelectric domains in synthetic Mn(3)B(7)O(13)X single-crystal boracites by light and electron microscopy

Crystals of halogen manganese boracite, the mineral Mg3B7O13Cl, which is currently found in bedded sedimentary deposits of anhydrite, gypsum and halite, have been grown by chemical transport reactions and were examined by polarizing light microscopy and scanning electron microscopy. For both methods the same as-grown samples were used without having to metallize the crystal faces. Comparative electron microscope images were useful not only for observing the charging mechanism of an insulating sample bombarded by an electron beam but also for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of a light microscope. EDS qualitative analysis of the crystal faces was performed for the three compositions under study, i.e. Mn3B7O13Cl, Mn3B7O13Br and Mn3B7O13I.