Preparation of PbS nano‐microcrystals with different morphologies and their optical properties

Abstract

PbS nano-microcrystals were prepared from Pb(OAc) 2 ·3H 2 O and sulfur in a solution without any surfactant using the solvothermal process. Different morphologies, mainly including polyhedron microcrystals and spherelike assemblies, were characterized using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). PbS nano-microcrystals with cubic crystal structure were detected using X-ray diffraction (XRD), electron diffraction (ED) and high resolution transmission electron micrograph (HRTEM) techniques. The optical properties were investigated by ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence spectroscopy (PL). The UV-vis absorption peaks of PbS exhibited a large blue-shift and the PL spectra had a strong and broad emission bands centered at 408 nm. The crystal growth mechanism of PbS was also discussed.

Thermodynamic Parameters of Lead Sulfide Chrystals in the Cubic Phase

“…These results do not contradict to experimental data given in [2], and to data of structural cards given in [24], where among compounds of lead chalcogenides are on the side of PbS cubic structure near the boundary between the cubic and orthorhombic modifications.…”

“…Effective use of this compound due to its low thermal conductivity at high temperatures [1], a lot ellipsoidal character of energy spectrum (N=4), low lattice thermal conductivity (~2.092 J/m•К) at relatively high carrier mobility (~0.1 m 2 /V s), high values of permittivity, low values of the band gap (0.41 eV [2]) [3] and their positive change with temperature [4], which are factors that contribute the efficient use of the material in thermoelectricity. Also, it is important to note that the band gap of lead sulfide is the highest among other lead chalcogenide compounds.…”

Account of surface contribution to thermodynamic properties of lead selenide films

“…The slight deviations from the rectangular crossposition of the crystalline planes also were observed in the modelling of the PbSe structure in [43], using the GAUSSIAN 03 and SBKJC bases set. These results are confirmed by the experimental data in [44], as well as by the structural data in [45]. The deviation of the theoretically calculated equilibrium structure from the typical for rock salt lattice values can be explained by significant deviation of the lattice spectrum from the Debye spectrum [46].…”