Mercuric iodide, bismuth tri-iodide and mercuric bromide nanoparticles were synthesized by the suspension method, using 1-octadecene (ODE) as suspension agent, Hg(NO₃)2.H₂O as Hg source, Bi(NO₃)₃.5H₂O as Bi source and I₂ and NaBr as halides sources. The influence of Octadecanethiol (ODT) as capping agent was also studied. Syntheses were performed with one (at a temperature T1 and during a time t1) or two steps (with a second step at a temperature T2 and during a time t2). The best synthesis conditions for nanostructures of the three halides are summarized in Table 1. 

Table 1
The synthesized nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution TEM (HR-TEM), energy dispersive spectrometry (EDS), X-Ray diffraction (XRD) and selected area electron diffraction (SAED).
Compounds identity was confirmed by XRD and EDS. Crystalline nanostructures were obtained for the three halides, with sizes from 5 to 500 nm. Mercuric iodide and mercuric bromide nanostructures have cubic and rod morphology, whereas bismuth tri-iodide ones have hexagonal and rod morphology. XRD, SAED and HR-TEM results show that the obtained nanostructures are crystalline, and that they have preferred orientations. In addition, nanostructures modification and coalescence was observed as consequence of the TEM beam irradiation.
Figures 1 to 3 show some examples of SEM, TEM, XRD and SAED results for representative samples of the three halides.
Taking into account the physical properties of these compounds, especially their high radiation absorption coefficients and wide band gaps, as far as the crystalline  nature of the obtained nanostructures, the nanostructures are being used as nuclei for inducing oriented and epitaxial growth of films for ionizing radiation imaging, opening the possibility of a new generation of imagers with enhanced performances. In addition, these nanocrystals are being experimented as acceptors into hybrid solar cells. 

Figure 1: Characterizations of a representative HgI₂ sample, a: XRD diagram, b: TEM image, c: SEM image, d: SAED diagram

Figure 2: Characterizations of a representative BiI₃ sample, a: XRD diagram, b: TEM image, c: HR-TEM image, d: SAED diagram

Figure 3: Characterizations of a representative HgBr₂ sample, a: XRD diagram, b: TEM image, c: HR-TEM, d: SAED diagram

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