Ultrasonic synthesis, formation mechanism and optical properties of single-crystalline Pb(OH)Br microrings

Novel elliptic Pb(OH)Br microrings have been controllably synthesized on a large scale by a simple sonochemical process in aqueous solution. The structure characterizations of such microrings were investigated in detail by means of X-ray powder diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the uniform orthorhombic phase of Pb(OH)Br microrings with good crystallinity can be obtained and such ring-like Pb(OH)Br is single crystalline with the (0 1 1) plane as the 2D exposed surface. The influence of reaction time and alkali sources on the evolution of structures has been studied. The possible hollowing growth mechanism for the Pb(OH)Br microrings has been discussed. Meanwhile, the ultraviolet–visible absorbance spectra and photoluminescence microrings show their ultraviolet absorption and green emitting behavior, indicating that the elliptic Pb(OH)Br microrings have great potential to be applied in luminescent and optoelectronic devices.