Structure, Chemistry, and Properties of Mineral Nanoparticles

Abstract

Nanoparticle properties can depart markedly from their bulk analog materials, including large differences in chemical reactivity, molecular and electronic structure, and mechanical behavior.The greatest changes are expected at the smallest sizes, e.g. 10 nm and below, where surface effects are expected to dominate bonding, shape and energy considerations. The precise chemistry at nanoparticle interfaces can have a profound effect on structure, phase transformations, strain, and reactivity. Certain phases may exist only as nanoparticles, requiring transformations in chemistry, stoichiometry and structure with evolution to larger sizes. In general, mineralogical nanoparticles have been little studied. WHAT'S REALLY DIFFERENT ABOUT NANOPARTICLESNanoparticles, particularly those with diameters of less than 10 nm, have a high proportion of atoms near their surfaces (ca. 16% for a 10 nm cube). Because of this, several important aspects of surfaces can drive deviations from bulk structure and chemistry at different size scales. Size also directly affects a number of other bulk properties due to restriction on wave function radius, separation of defects and interacting strain fields, the relative overall dominance of bulk or surface energy, and changes in vibrational properties. Studies of nanoparticles connect with several other important scientific areas dealing with lower

Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

“…Importantly, the differences observed in the analyzed samples are explained by the long-range character of electrostatic interactions affecting (sub-)micronic particles. They differ in essence from potential surfaceinduced relaxation effects which occur at the atomic scale and can become dominant in nanometer-sized particles (Waychunas and Zhang 2008).…”

Effects of different Ti-doping methods on the structure of pure-silica MCM-41 mesoporous materials

“…The pre-edge peak position and intensity can distinguish four-, five-, and sixfold coordinations of titanium atoms [32][33][34]. In the order of the four-, five-and sixfold coordination, the pre-edge peak energy shifts towards higher values, and the peak intensity simultaneously decreases [35][36][37].…”

Importance of doping, dopant distribution, and defects on electronic band structure alteration of metal oxide nanoparticles: Implications for reactive oxygen species

“…Furthermore, rigorous and detailed characterizations of dopants and/or defects also are critical. Such characterization can be performed with X-ray diffraction (Wang et al, 2006), nano beam diffraction with high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) (Ward et al, 2014), slow positron beam spectroscopy (Xue et al, 2013), photo-luminescent (PL) emission (Sekiguchi et al, 2000;Zhang et al, 2014), X-ray absorption spectroscopy (XAS) (Brown and Parks, 2001;Rossi et al, 2014;Waychunas and Zhang, 2008), X-ray standing wave measurements , and X-ray spectromicroscopy (STXM) (Chen et al, 2014;Myneni et al, 1999;Warwick et al, 1998). Not only material scientists but also nanotxicologists can add these characterization tools to the routine assessment sequence, depending on the ROS-generation ability of the MONPs (predicted or characterized by the material scientists).…”