| Abstract [eng] |
Phosphate compounds are a family of materials widely applicable in agriculture, pharmaceuticals, optics, energy and other fields to name a few. The diversity arises from their ability to form wide range of crystalline structures, ranging from simple orthophosphates to complex polyphosphate networks, which exhibit different physical and chemical properties. During this research, materials with wide range of applications including medicine and optics (Calcium halophosphates) and solid-state electrolyte in batteries (Zirconium phosphates) were investigated. The aim of this work was to analyze multiple types of phosphorus-based materials using advance solid-state NMR methods. First group of materials, calcium halophosphates, exhibit crystalline and glassy-type structures and its dependance on synthesis parameters. Characterization of structural phases of the materials employs the properties of quadrupolar nuclei, 35,37Cl, present in the structure of the materials. 35,37Cl NMR enables observation of quadrupolar interaction, which is sensitive to structural changes in the environment of the nucleus. The second group of materials, zirconium phosphates, are intercalated with NH4+, K+ and Na+ ions, changing their structure and properties at a molecular level. Employed 31P and 23Na, 1D and 2D MAS NMR methods enable characterization of the compounds – reveals structural changes after intercalation, doping mechanisms and dipolar interaction between nuclei. It was found, that the ratio of KCl and CaCl2 salts in the synthesis medium, enables the control of structural phases present in the calcium halophosphate samples. KCl salt promotes formation of glassy-type structure while CaCl2 – crystalline structural phase. Using joint 35Cl MAS NMR and SEM results we hypothesize, that samples consist of crystalline phase surrounded by glassy-type structure. This hypothesis was confirmed using TEM imaging results. Additionally, we confirmed presence of α- and γ- ZrP polymorphs, intercalated with NH4+, K+ and Na+ ions, and determined chemical shift of the characteristic peaks. In conjunction with 31P-31P 1Q-2Q NMR spectra, we determined dipolar interaction present in the crystalline structure, which enabled determination of crystal motifs in the samples. |
