The calcium silicate hydrates

Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

Dense, highly ordered monolayers can be prepared by the adsorption of octadecylphosphonic acid (ODPA) onto nonporous ZrO2, TiO2, and zirconated silica powders. ODPA reacts strongly with Al2O3 to form a bulk (aluminoalkyl)phosphonate. The infrared spectra of the ODPA monolayers indicate a degree of conformational order comparable to self-assembled monolayers on planar substrates. From the solid-state 31P and 13C NMR spectra, the strength of the surface interaction and the degree of conformational order decrease in the following order:  zirconated silica > ZrO2 > TiO2. Although the inner methylenes are primarily in an all-trans conformation, the chain termina are highly disordered. In the case of zirconated silica, there is evidence for the formation of some bulk zirconium alkylphosphonate. Proton line width measurements from 2D WISE NMR experiments reveal that considerable chain mobility is present in the ODPA monolayers on ZrO2 and TiO2, in contrast to bulk crystalline phases.

Self-Assembled Monolayers of Alkylphosphonic Acids on Metal Oxides

Advanced solid-state NMR methods for the elucidation of structure and dynamics of molecular, macromolecular, and supramolecular systems.

Nuclear magnetic resonance (NMR) spectroscopy continues to evolve as a primary technique in the study of solids. This review briefly describes some developments in modern NMR that demonstrate its exciting potential as an analytical tool in fields as diverse as physics, chemistry, biology, geology, and materials science. Topics covered include motional narrowing by sample reorientation, multiple-quantum and overtone spectroscopy, probing porous solids with guest atoms and molecules, two-dimensional NMR studies of chemical exchange and spin diffusion, experiments at extreme temperatures, NMR imaging of solid materials, and low-frequency and zero-field magnetic resonance. These developments permit increasingly complex structural and dynamical behavior to be probed at a molecular level and thus add to our understanding of macroscopic properties of materials.

https://science.sciencemag.org/content/sci/246/4926/71.full.pdf

Some developments in nuclear magnetic resonance of solids.

Recent trends of general interest in high-resolution NMR of solids are mentioned, and some examples briefly discussed. Stress is laid on the use of the multiple-pulse technique, particularly when combined with magic-angle spinning to give CRAMPS. Two studies of proton CRAMPS are described, one concerning hydrogen bonding in carboxylic acids and the other involving phosphonic acid derivatives. The relationship between proton isotropic chemical shifts and hydrogen-bond distances is explored in some detail. A clear correlation is found.

Perspectives in high-resolution solid-state nuclear magnetic resonance, with emphasis on combined rotation and multiple-pulse spectroscopy

Fluorine in silicate glasses : a multinuclear nuclear magnetic resonance study

A 29Si and 27Al magic angle spinning nuclear magnetic resonance study is reported for differently synthesized mullites. The 29Si MAS NMR spectra of all samples are essentially identical. They consist of a main resonance at -86.8 ppm, a shoulder around -90 ppm and a second resonance at -94.2 ppm. The main resonance is interpreted as being due to a sillimanite-type geometry around Si and the second one is tentatively assigned to a Si environment typical for mullite. The 27Al MAS NMR spectra of sinter- and fused-mullite measured at different Larmor frequencies revealed clearly the presence of three distinct Al sites in mullite, i.e. of octahedral (M1), tetrahedral (M2) and distorted tetrahedral (Al*) sites.

29Si and 27Al MAS NMR spectroscopy of mullite

The structural role of H 2 O in Na 2 Si 4 O 9 glasses has been investigated by high-resolution solid-state NMR methods ( 29 Si MAS, 29 Si CP MAS, 1 H MAS, 1 H CRAMPS). As a result of this study it is shown that (i) H 2 O does depolymerize the silicate network, and (ii) both Si-OH and molecular water are present in hydrous sodium silicate glasses

Lawrence H. Merwin

Papers

Perspectives in high-resolution solid-state nuclear magnetic resonance, with emphasis on combined rotation and multiple-pulse spectroscopy

Fluorine in silicate glasses : a multinuclear nuclear magnetic resonance study

29Si and 27Al MAS NMR spectroscopy of mullite

Structural role of water in sodium silicate glasses: results from silicon-29 and proton NMR spectroscopy

Structure of Na3−3xAlxPO4, x = 0 to 0.5