HgI₂ nanostructures obtained hydrothermally for application in ionizing radiation detection

The compound semiconductor HgI₂ has been widely studied and employed as a material for ionizing radiation detection. Monocrystal growth is an intricate method for obtaining materials for this application. With the aim of finding a simpler and more effective way to develop ionizing radiation detectors, we employed HgI₂ nanostructures subjected to a hydrothermal treatment and then pressed for this purpose. In the synthesis procedure, aqueous solutions of Hg(NO₃)₂ and NaI were mixed until their reaction completed and the suspension obtained was then placed in a homemade autoclave and heated at 120 °C for 2, 10 or 24 h. We confirmed the HgI₂ tetragonal phase by powder XRD in all cases, independently of the synthesis conditions employed. Nanoparticles were characterized by their size and morphology by TEM. We used the HgI₂ nanostructures to obtain a pellet by applying 0.7 GPa of pressure at room temperature. The pellet was then used to construct the detector, and we studied the electrical properties of the detector and its response to ²⁴¹Am sources of different exposure rates. The resistivity and signal-to-noise ratio obtained are of the order of those reported for HgI₂ detectors assembled with monocrystals. The results obtained in this work encourage us to work further on this topic, improving the method, scaling the detector's size and studying its spectrometric grade. (paper)