Sökning: "29Si NMR"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden 29Si NMR.

1. 1. Structural Investigations of Complex Glasses by Solid-state NMR

   Författare :Ekaterina Leonova; Mattias Edén; Robin Harris; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; glass; glass structure and properties; NMR; magic angle spinning; chemical shift; Physical chemistry; Fysikalisk kemi; Physical Chemistry; fysikalisk kemi;

   Sammanfattning : This PhD thesis presents structural investigations of amorphous inorganic materials: oxide and oxynitride glasses and mesoporous bioactive glasses (MBGs), by solid-state Nuclear Magnetic Resonance (NMR). Lanthanum oxide and oxynitride [La-Si-(Al)-O-(N)] glasses have a large number of potential applications due to their physical properties. LÄS MER

3. 2. Nuclear magnetic resonance studies on bentonite in complex mixed systems

   Författare :Alexander S. Goryan; Willis Forsling; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bentonite; montmorillonite; 23Na; 31P; 29Si NMR; interaction; ion exchange; sorption; Chemistry of Interfaces; Gränsytors kemi;

   Sammanfattning : In this work 23Na MAS NMR was validated as a successful quantitative method for studies of exchanging sodium in bentonites useful, in particular, for studies of ion-exchange kinetics. Na-enriched bentonites equilibrated in a re-circulated process water at iron-oxide pelletizing plants may acquire properties of Ca-bentonites after already 20 minutes of the equilibration time, since >50 % of sodium ions will be exchanged by calcium ions during first minutes of bentonite placed in contact with the process water. LÄS MER

4. 3. Aqueous behaviour of characteristic molecules in the synthesis of porous silica materials : - an atomistic description

   Författare :Emelie Nilsson; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; porous silica; struture directing agents; 29Si-NMR; neutron scattering; empirical potentail structure refinement; micelles;

   Sammanfattning : The formation process of porous silica materials is an intricate process, involving a number of components that interact to form a highly organized material. Both zeolites and mesoporous silica materials typically require the presence of organic structure director agents (SDAs) around which the silica network polymerizes. LÄS MER

5. 4. Composition-Structure Correlations of Bioactive Glasses Explored by Multinuclear Solid-state NMR Spectroscopy

   Författare :Renny Mathew; Mattias Edén; Robert Hill; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bioactive glasses; glass structure; orthophosphate distribution; solid-state NMR; dipolar interactions; dipolar recoupling; multiple-quantum spin counting; READOR; REAPDOR; fysikalisk kemi; Physical Chemistry;

   Sammanfattning : This PhD thesis presents a study of structure-composition correlations of bioactive glasses (BGs) by employing solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.Silicate-based Na2O−CaO−SiO2−P2O5 BGs are utilized clinically and are extensively investigated for bone regeneration purposes. LÄS MER

7. 5. Solid state 29Si and 27Al magic angle spinning NMR studies of mechanochemically modified cement

   Författare :Karin Johansson; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry of Interfaces; Gränsytors kemi;

   Sammanfattning : Solid state 29Si and 27Al magic angle spinning (MAS) NMR spectroscopy has been used to investigate how mechanochemical modification affects the hydration kinetics, as well as the structural and chemical properties, in cement blends. The modification comprises intensive treatment of rapid hardening Portland cement with condensed silica fume additive in a vibrating grinding mill. LÄS MER