Preparation And Characterization Of New Borate Nanomaterials

Borate have important applications in many fields, such as the flame-retardant, composite reinforced material and tribology. In practical application, their performances are often affected by nanomaterials structure and morphology. Therefore, it is of significance to the controlled preparation of the borate nanomaterials morphology.In this thesis, we have prepared different new morphologies of the calcium borate, zinc borate and magnesium borate nano-structure by hydrothermal (solvothermal) method and high-temperature solid-phase method. All of the products have been characterized by XRD, EDS, FT-IR, SEM and TEM. Details are as follows:(1) The oval-like 4CaO·5B₂O₃·7H₂O microspheres have been fabricated by a hydrothermal method with the help of the surfactant polyethylene glycol(PEG-300), using CaCl₂·2H₂O and Na₂B₄O₇·10H₂O as source matrials. SEM and TEM results indicate that 4CaO·5B₂O₃·7H₂O oval-like microspheres are constructed by ladder-like layers, and each layer is made up of numerous densely packed nanoplates with the thickness of 50-100 nm and the diameter of several microns. Moreover, sheaf-like and sphere-like calcium borate nanostructure have been prepared by hydrothermal (solvothermal) method, using Ca(NO₃)₂·4H₂O and Na₂B₄O₇·10H₂O as raw materials.(2) Cluster-like zinc borate (4ZnO·B₂O₃·H₂O) nanostructure has been synthesized by solvothermal method in the presence of KNO₃ and dioctyl sodium sulfosuccinate (AOT), with the source materials of ZnSO₄·7H₂O and Na₂B₄O₇10H₂O. SEM results show that cluster-like 4ZnO·B₂O₃·H₂O nanostructure consists of nanoribbons with the thickness of 80-200 nm, the width of 100-300 nm and the length of a few micrometers. In addition, flake-like zinc borate nanostructure has been prepared in ethanol solvent, using Zn(Ac)₂·2H₂O and H₃BO₃ as raw materials. The nanoplates assembled sphere-like structure of zinc borate has been obtained by solution method, using Zn(Ac)₂·2H₂O and Na₂B₄O₇·10H₂O as raw materials.(3) Sheaf-like magnesium borate nanostructure has been prepared by a solvothermal method with the raw materials of MgCl₂·6H₂O and Na₂B₄O₇·10H₂O. SEM and TEM results show that the sheaf-like magnesium borate is composed of nanowhisker with the thickness of 50 nm. In addition, globe-shaped cactus magnesium borate microsphere was obtained by a solvothermal method, with the source materials of MgSO₄ and potassium pentaborate; rod-like magnesium borate was obtained with the source materials of Mg(NO₃)₂·6H₂O and H₃BO₃ by high-temperature solid-phase method.The obtained experimental results are helpful to enrich borate chemistry, lay a experimental foundation for selecting the practical borate nanomaterials and are of practical significance to promote its application.