Tsutomu Sato

Bio: Tsutomu Sato is an academic researcher from Joetsu University of Education. The author has contributed to research in topics: Relative humidity & Saponite. The author has an hindex of 1, co-authored 1 publications receiving 81 citations.

Expansion characteristics of montmorillonite and saponite under various relative humidity conditions.

Abstract: The basal spacings of the homoionic (Na+, K+ and Ca2+) montmorillonite (T1) and saponite (SapCa-1) were examined by X-ray powder diffraction (XRD) analysis under the atmospheres of relative humidity (RH). RH was controlled by ReCX (Relative humidity Control system for X-ray diffractometer) precisely in the range of 0 to 100% RH. The variations of basal spacing were almost similar in both minerals at the range of 0 to 80% RH. However, noticeable differences between the hydration state of T1 and SapCa-1 were observed at 100% RH. It was explained that the differences were caused by charge localization and hydroxyl orientation in silicate layer because of these specimens having similar layer charge. In the region between 2 hydration states, irrational and asymmetrical reflections were observed. These reflections indicated interstratified structure of 2 hydration states. Especially at 60% RH, that the segregation structure was recognized. The existence of 2 phases indicates that there is heterogeneity in its charge density of layer.

Investigation of smectite hydration properties by modeling experimental X-ray diffraction patterns: Part I. Montmorillonite hydration properties

Abstract: Hydration of the <1 μm size fraction of SWy-1 source clay (low-charge montmorillonite) was studied by modeling of X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Li-, Na-, K-, Mg-, Ca-, and Sr-saturated specimens. The quantitative description of smectite hydration, based on the relative proportions of different layer types derived from the fitting of experimental XRD patterns, was consistent with previous reports of smectite hydration. However, the coexistence of smectite layer types exhibiting contrasting hydration states was systematically observed, and heterogeneity rather than homogeneity seems to be the rule for smectite hydration. This heterogeneity can be characterized qualitatively using the standard deviation of the departure from rationality of the 00 l reflection series (ξ), which is systematically larger than 0.4 A when the prevailing layer type accounts for ~70% or less of the total layers (~25% of XRD patterns examined). In addition, hydration heterogeneities are not distributed randomly within smectite crystallites, and models describing these complex structures involve two distinct contributions, each containing different layer types that are interstratifed randomly. As a result, the different layer types are partially segregated in the sample. However, these two contributions do not imply the actual presence of two populations of particles in the sample. XRD profile modeling also has allowed the refinement of structural parameters, such as the location of interlayer species and the layer thickness corresponding to the different layer types, for all interlayer cations and RH values. From the observed dependence of the latter parameter on the cation ionic potential ( v / r; v = cation valency and r = ionic radius) and on RH, the following equations were derived: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (1W)\ =\ 12.556\ +\ 0.3525\ {\times}\ ({ u}/\mathit{r}\ {-}\ 0.241)\ {\times}\ ({ u}\ {\times}\ RH\ {-}\ 0.979)\] \end{document} \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (2W)\ =\ 15.592\ +\ 0.6472\ {\times}\ ({ u}/\mathit{r}\ {-}\ 0.839)\ {\times}\ ({ u}\ {\times}\ RH\ {-}\ 1.412)\] \end{document} which allow the quantification of the increase of layer thickness with increasing RH for both 1W (one water) and 2W (two water) layers. In addition, for 2W layers, interlayer H2O molecules are probably distributed as a unique plane on each side of the central interlayer cation. This plane of H2O molecules is located at ~1.20 A from the central interlayer cation along the c* axis.

Effects of Layer Charge, Charge Location, and Energy Change on Expansion Properties of Dioctahedral Smectites

Abstract: Terra rossa samples were taken from the B horizons of soil profiles and from cracks within limestone in Italy. The average annual temperature (AAT) of the sites ranged from 8.4 to 20.3°C and the average annual precipitation (AAP) from 511 to 3113 mm, with either a 5–6 month water deficit or a large water surplus. Goethite and hematite were identified in all the samples. Under a moist (> 1700 mm AAP) and cool (13°C AAT) climate, a xeric, hematitic pedoenvironment was preserved by the well-litified carbonate rock. Hematite occurred in trace amounts, even with an AAT of 8.4°C and an AAP of 3300 mm, confirming the specific role of the hard limestone on the pedoclimate of terra rossa. The lowest mean crystallite dimension of goethite and hematite was found in the samples from the wettest sites, and in these samples hematite was nearly free of Al substitution. Rubification in terra rossa appeared to be due to the specific pedoenvironment. The hematite cannot be considered a relict phase formed under another climate. Illite and kaolinite were the main clay minerals in samples from xeric sites whereas more weathered clays, such as Al-interlayered vermiculite, occurred in cool, moist sites. We postulate that the processes of rubification and vermiculitization could have taken place at the same time. The effects of layer charge magnitude and location on expansion were represented by an energy change (expansion energy: ΔEr) during the hydration and solvation processes. Plots of basal spacings versus ΔEr show a reasonable relationship; the spacings generally decrease stepwise as the value of ΔEr increases. The basal spacings of K-samples with glycerol solvation, Na-saturated and K-saturated samples at 100% RH are apt to contract stepwise with increasing value of ΔEr. For these samples, the figures showing the relationship between each expanded phase and the charge characteristics are obtained from the isoquants of ΔEr, given the boundary of the expanded phases. A behavior test using these figures may be combined with the Greene-Kelly test to estimate the amount and the location of the layer charge of common smectites.

Investigation of dioctahedral smectite hydration properties by modeling of X-ray diffraction profiles: Influence of layer charge and charge location

Abstract: Hydration of the <1 μm size fraction of a high-charge montmorillonite (Clay Minerals Society Source Clay SAz-1), and of low- and high-charge beidellites (Source Clays SbId-1 and SbCa-1, respectively) was studied by modeling of X-ray diffraction patterns recorded under controlled relative humidity (RH) for Sr- and/or Ca-saturated specimens. The influence of layer charge and charge location on smectite hydration was studied. Distribution of layers with different hydration states (dehydrated – 0W, monohydrated – 1W, bi-hydrated – 2W, or tri-hydrated – 3W) within smectite crystals often leads to two distinct contributions to the X-ray diffraction pattern, each contribution having different layer types randomly interstratified. Structure models are more heterogeneous for beidellite than for montmorillonite. For beidellite, two distinct populations of particles with different coherent scattering domain sizes account for the heterogeneity. Increased hydration heterogeneity in beidellite originates also from the presence of 0W (non-expandable) and of 1W layers under high relative humidity (RH) conditions. Similarly, after ethylene-glycol (EG) solvation, some beidellite layers incorporate only one plane of EG molecules whereas homogeneous swelling was observed for montmorillonite with the systematic presence of two planes of EG molecules. For montmorillonite and beidellite, the increase of layer charge shifts the 2W-to-1W and the 1W-to-0W transitions towards lower RH values. For all samples, layer thickness of 0W, 1W, and 2W layer types was similar to that determined for low-charge SWy-1 montmorillonite (Source Clay SWy-1), and no change of layer thickness was observed as a function of the amount or of the location of layer charge. Layer thickness however increased with increasing RH conditions.

Synthesis and Delamination of Layered Manganese Oxide Nanobelts

Abstract: This paper describes systematic studies on the synthesis and delamination of manganese oxide nanobelts with the birnessite-type layered structure. K-birnessite nanobelts of K0.33MnO2·0.5H2O, which typically had a length of several tens of micrometers, a width of hundreds of nanometers, and a thickness of ∼15 nm, were synthesized by hydrothermally treating a KMnO4–MnCl2 mixture in a highly concentrated KOH aqueous solution. The nanobelt growth was found to be controlled by the KOH concentration and the molar ratio of Mn2+/MnO4− in the starting reaction mixture. The K-birnessite nanobelts were converted to H-birnessite, H0.08MnO2·0.7H2O, by treatment with a (NH4)2S2O8 aqueous solution, retaining their high crystallinity and beltlike morphology. Swelling and delamination behaviors of the H-birnessite nanobelts in aqueous solutions of quaternary ammonium hydroxides were studied in detail. In tetrabutylammonium hydroxide (TBAOH) solutions, the H-birnessite showed a limited swelling and delamination behavior, w...