Role Of Hexamethylenetetramine Research Articles

Controlled growth of hexagonal nanocrystals Co and Gd co-doping ZnO by hydrothermal method

The control of nanostructured zinc oxide (ZnO) materials is essential for the development of smart and functional nanoscale devices. Using controlled hydrothermal growth conditions, cobalt (Co)- and gadolinium (Gd)-co-doped zinc oxide hexagonal nanocrystals were synthesized at a low temperature (70°C). The role of hexamethylenetetramine (HMTA; C6H12N4) in engineering pure and doped zinc oxide morphology was examined. The results indicated that the hexagonal plates are transformed into a hexagonal flowerlike structure by changing the molar ratio of HMTA/precursors. The possible growth mechanism of the formation of hexagonal nanocrystals (hexagonal plates and nanoflowerlike structure) is discussed. The magnetic properties exhibited enhanced ferromagnetism after the incorporation of gadolinium into the zinc oxide matrix. An enhancement in saturation magnetization is discussed mainly in correlation with the strain effect. These doped zinc oxide nanostructures are expected to drive improvements mainly in the performance of spintronic devices.

Effects of Hexamethylenetetramine on the Nucleation and Radial Growth of ZnO Nanowires by Chemical Bath Deposition

The growth of ZnO nanowires by chemical bath deposition (CBD) is of great potential for their integration into nanoscale devices. However, the effects of the chemical precursors in solution are still under debate, such as the role of hexamethylenetetramine (HMTA). In order to tackle this issue, these effects are thoroughly disentangled from the effects of the structural morphology of the ZnO seed layer and investigated through a large number of nonequimolar CBDs over a broad range of chemical precursor concentrations and ratios. The analysis is further supported by thermodynamic simulations yielding theoretical solubility plots and speciation diagrams of Zn(II) species. It is shown that the ZnO deposited volume and, to some extent, the length of ZnO nanowires are directly related to the supersaturation in solution, which strongly depends on the chemical precursor concentration and pH. A slight excess of HMTA with respect to zinc nitrate is required to reach the largest axial growth rate of ZnO nanowires. ...

Effect of hydroxide anion generating agents on growth and properties of ZnO nanorod arrays

In chemical growth of 1-D ZnO nanorods the selection of hydroxide anion generating agent plays a crucial role in determining the growth rate and morphological features. Due to misconception regarding the role of hexamethylenetetramine (HMTA) in the growth of ZnO nanorods, it is heavily used as hydroxide anion generating agent for ZnO nanorod growth. Though it needs repetitive renovation of growth solution and longer time deposition for the growth of high aspect ratio ZnO nanorods. Here we have carried out a comparative study on the effect of hydroxide anion generating agents (HMTA and ammonia) on growth, morphological, structural, chemical, optical, and photo-electrochemical properties of ZnO nanorods, in view to assist in the selection of the these agents in ZnO nanorod growth.

Effect of solution concentration on the functional properties of ZnO nanostructures: Role of Hexamethylenetetramine

In this research, ZnO nanorods have been successfully synthesized via wet chemical method. XRD results revealed the single phase nature with the wurtzite structure of the as prepared ZnO nanorods. By only varying the concentration of Hexamethylenetetramine (HMT) in the solution, morphology of ZnO changed from hexagonal facet nanorods to pencil like nanorods and size of nanorods also changed. The band gap of as-synthesized ZnO nanorods was found to increase with increasing the concentration of HMT in the solution. The narrow full-width at half-maximum (FWHM) of the UV emission of PL spectra indicated that the grown ZnO nanorods have high crystal quality and is well matched with the obtained XRD results. These results revealed that the concentration of Hexamethylenetetramine plays a vital role to control the properties of ZnO nanorods.

A novel sol–gel synthetic route to alumina nanofibers via aluminum nitrate and hexamethylenetetramine

Attempts have been made to prepare alumina nanofibers by hydrolyzing aluminum nitrate in the presence of hexamethylenetetramine (HMTA) followed by the supercritical fluid drying (SCFD) process. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen physisorption. The results show that δ-Al 2O 3 nanofibers with diameter of 2 nm, length of 50 nm and with BET surface areas of 412.6 m 2 g − 1 were successfully synthesized. The thermal evolution of the fibers and the role of hexamethylenetetramine were also briefly discussed.

Infrared investigation of the structure of ureaformaldehyde oligomers synthesized in the presence of amines

The IR spectra of urea-formaldehyde oligomers synthesized in the presence of hexamethylene tetramine (HMTA) and ammonia have been investigated. Absorption bands relating to the triazinone ring have been identified, and the number of rings in the oligomer has been quantitatively evaluated on the basis on the absorption bands. The mechanism of formation of cyclic structures during the reaction of condensation of urea with formaldehyde is described and the role of HMTA and the influence of the HMTA concentration on the degree of substitution of the rings formed is revealed. A scheme of formation of cyclic structures is proposed.