Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites
The domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.
Nano and micro reoriented domains and their relation with the crystal structure in the new ferroelectric boracite Zn3B7O13Br
A new zinc brome boracite Zn3B7O13Br has been grown by a chemical transport reaction in closed quartz ampoules at 920 K. The crystal structure was characterized by Rietveld refinement. Ferroelectric nano and micro reorientable domains were found in this material using polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Chemical analysis was performed with x-ray energy dispersive spectroscopy (EDX). In the crystal, a new structure transition at 586 K from orthorhombic (Pca 21) to cubic cell () has been found. This transition was corroborated by differential scanning calorimetry (DSC).
X‐ray evidence for CrCO3, VBO3 and TiBO2 with calcite structure
The borates were prepd. by heating the metal oxides, halides, and H3BO3 in a sealed quartz tube. Structures were deduced from x-ray powder diagrams.