Wet-chemistry synthesis of shape-controlled Ag ₃ PO ₄ crystals and their 3D surface reconstruction from SEM imagery

A simple chemical solution-based synthesis route has been developed to prepare uniform and shape-controllable Ag ₃ PO ₄ crystals. Tetrapod- and cube-shaped crystals having a size of about 9–10 μm were prepared from AgNO ₃ and NH ₄ H ₂ PO ₄ precursors, and pseudo-octahedral (equiaxial) crystals were prepared from AgNO ₃ and (NH ₄ ) ₂ HPO ₄ . TEM analysis revealed Ag ₃ PO ₄ crystals to be electron beam sensitive materials, which under a voltage of 200 kV decompose to the metallic Ag, thereby demonstrating the difficulty in determining crystal facets and structural defects using conventional electron diffraction studies. UV–Vis diffuse reflectance spectroscopy was used to study the correlation between structural and optical properties of surfaces of Ag ₃ PO ₄ crystals. Furthermore, a spatial 3-dimentional (3D) reconstruction of Ag ₃ PO ₄ surface structures was performed from SEM images. The reconstruction produced realistic 3D mesh models, insomuch that the 3D reconstructed structures provided extra information about the examined crystals. Results suggested that the proposed synthesis route and performed spatial reconstruction of Ag ₃ PO ₄ had the potential for simulating processing conditions to produce various microcrystals and explore material surface structures and reconstruction of microstructures.