Nanometer functional materials from explosives

Abstract

ABSTRACT The growth of Li 1+x Mn 2 O 4 via detonation reaction was investigated with re spect to the presence of energetic precursors, such as the metallic nitrates and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Li 1+x Mn 2 O 4 with 1~2 e m spherical morphology and more uniform secondary particles, but with smaller primary particles of diameters from 20 to 60 nm and a variety of morphologies were found. The oxides produced by this cheap method affirmed the validity of detonation synthesis of nano-size powders. Keywords: Crystal morphology, Nanostructures, X-ray diffraction, Growth from high temperature solutions, Inorganic compounds, Lithium compounds, Manganites, Nanomaterials, Oxides 1. INTRODUCTION The spinel lithium manganese synthesized by the conventional method has several disadvantages, such as inhomogeneity, irregular morphology, large particle size, broad particle size distribution, high synthesis temperature and repeated grinding. To overcome the disadvantages of solid-state reaction, several soft chemistry methods, such as hydrothermal method, sol ¦gel, solvothermal method, coprecipitation and pechini process have been developed. Among these methods, solvothermal method should use organic methods. It is toxic and unsafe. The sol ¦gel, coprecipitation and pechini process need further calcination and grinding. The hydrothermal synthesis is a powerful method to prepare various oxides. The advantage features of this method are to control the morphology, the particle size and the crystalline of products. However, most spinel LiMnO products synthesized by the hyd rothermal method reported in literature were powders with irregular shape. Jianjun Liu et al [1] thought that the shock-induced chemical reactions leading to synthesis of compounds in powder mixtures occurred under conditions of the microsecond -scale duration of the high pressure, stress, strain- rate, and temperature states. Such high-rate chemical reactions can be advantageously utilized to synthesize materials with novel phases and unique microstructures, or to generate radically modified materials with physically interesting or technologically useful properties. Shuhua Ma et al [2] said that Spinel structure Li–Mn–O compounds are the most promising lithium ion insertion electrode materials for rechargeable lithium batteries because of a number of advantages over their alternatives, e.g., a lower cost compared with LiCoO