NMR techniques: A non-destructive analysis to follow microstructural changes induced in ceramics

Influence of porosity and relative humidity on consolidation of dolostone with calcium hydroxide nanoparticles: Effectiveness assessment with non-destructive techniques

“…This can be interpreted as greater microestructural homogeneity, due to the presence of pores of nearly the same dimension of those from specimen 33RH-DOL. However, after treatment T1 curve of specimen 33RH-DOL slightly changes, just a small shift of the peak towards higher relaxation times, indicating the presence of larger pores [27]. This is in agreement with ESEM results where it was observed that some pores became larger due to the dolomite attack by the consolidating product in a dry environment.…”

“…However, after treatment, T1 curve of specimen 75RH-DOL shows significant differences, since it goes from a monomodal to a bimodal distribution, giving rise to a narrower curve and the appearance of a broad peak with a low signal but with shorter relaxation times ( Fig.9). This behavior in 75RH-DOL where T1 decreases can be explained by more interconnected porosity and in smaller pores [27]. The slight narrowing of the larger curve can be explained by a higher homogeneity in some pores but the appearance of another broader small peak (bimodal distribution) showing wider distributions, reflects the presence of larger pores.…”

“…Before the treatment, these results show lower and more homogeneous values of relaxation times T1 and T2 in the specimen 33RH-DOL compared to 75RH-DOL. Higher T1 and T2 values are related with larger pores [27,28]. If before treatment, MRI results show lower T1 and T2 values for specimen 33RH-DOL, this would mean the presence of smaller pores in this specimen compared to 75RH-DOL.…”

Application of Magnetic Resonance Techniques to evaluate soil compaction after grazing

“…T2 relaxation is directly related with molecular mobility, i.e., slower molecular mobility is associated with shorter relaxation time (Duval et al, 2010). The values for T2 relaxation time are therefore related with pore sizes, and samples with larger pore sizes have longer T2 relaxation times (Viola et al, 2006;Appolonia et al, 2001). Bird et al (2005) associated long relaxation times with the free water located between the aggregates and in the interiors of the larger-sized pores, whereas shorter relaxation times were associated with the water bound to the smaller-sized pores located inside the aggregates.…”

Water1H NMR Technique to Analyse the Porous Structure of Ceramics

“…From this point of view, Nuclear Magnetic Resonance (NMR) Imaging (MRI) and Relaxometry (MRR) experiments offer a unique opportunity to study different kinds of samples in several fields, such as medical, biological, biochemical, and also in material science. [3][4][5][6][7] It is a common practice to relate a distribution of relaxation times (multi-exponential relaxation) to a distribution of pore sizes, based on the assumption that the surfaces are uniformly effective in causing relaxation and that water molecules within a pore are mixed by diffusion in a local relaxation time (fast diffusion regime). We verified that the fast diffusion regime applies by noting that the diffusion distance (2 DT 1 ) 0.5 is greater than relevant pore dimensions shown by SEM images.…”