Layered zinc hydroxides (LZHs) with the general formula (Zn 2+ ) x (OH – ) 2 x − my (A m – ) y · n H 2 O (A m – = Cl – , NO 3 – , ac – , SO 4 2– , etc) are considered as useful precursors for the fabrication of functional ZnO nanostructures. Here, we report the synthesis and structure characterization of the hitherto unknown “binary” representative of the LZH compound family, Zn 5 (OH) 10 ·2H 2 O, with A m – = OH – , x = 5, y = 2, and n = 2. Zn 5 (OH) 10 ·2H 2 O was afforded quantitatively by pressurizing mixtures of ε-Zn(OH) 2 (wulfingite) and water to 1–2 GPa and applying slightly elevated temperatures, 100–200 °C. The monoclinic crystal structure was characterized from powder X-ray diffraction data (space group C 2/ c , a = 15.342(7) Å, b = 6.244(6) Å, c = 10.989(7) Å, β = 100.86(1)°). It features neutral zinc hydroxide layers, composed of octahedrally and tetrahedrally coordinated Zn ions with a 3:2 ratio, in which H 2 O is intercalated. The interlayer d (200) distance is 7.53 Å. The H-bond structure of Zn 5 (OH) 10 ·2H 2 O was analyzed by a combination of infrared/Raman spectroscopy, computational modeling, and neutron powder diffraction. Interlayer H 2 O molecules are strongly H-bonded to five surrounding OH groups and appear orientationally disordered. The decomposition of Zn 5 (OH) 10 ·2H 2 O, which occurs thermally between 70 and 100 °C, was followed in an in situ transmission electron microscopy study and ex situ annealing experiments. It yields initially 5–15 nm sized hexagonal w-ZnO crystals, which, depending on the conditions, may intergrow to several hundred nm-large two-dimensional, flakelike crystals within the boundary of original Zn 5 (OH) 10 ·2H 2 O particles.

Cellulose fibrils are the structural backbone of plants and, if carefully liberated from biomass, a promising building block for a bio-based society. The mechanism of the mechanical release—fibrillation—is not yet understood, which hinders efficient production with the required reliable quality. One promising process for fine fibrillation and total fibrillation of cellulose is cavitation. In this study, we investigate the cavitation treatment of dissolving, enzymatically pretreated, and derivatized (TEMPO oxidized and carboxymethylated) cellulose fiber pulp by hydrodynamic and acoustic (i.e., sonication) cavitation. The derivatized fibers exhibited significant damage from the cavitation treatment, and sonication efficiently fibrillated the fibers into nanocellulose with an elementary fibril thickness. The breakage of cellulose fibers and fibrils depends on the number of cavitation treatment events. In assessing the damage to the fiber, we presume that microstreaming in the vicinity of imploding cavities breaks the fiber into fibrils, most likely by bending. A simple model showed the correlation between the fibrillation of the carboxymethylated cellulose (CMCe) fibers, the sonication power and time, and the relative size of the active zone below the sonication horn.

The vapor pressure measurement unit from borosilicate glass was assembled for determination of partial pressures of water in aggressive acidic media using the transpiration method. Three ternary systems H2O–HNO3–RE­(NO3)3 (RE = Pr, Nd, Sm) were investigated. The experimental results in ternary systems were compared with the estimation by the Pitzer model and Zdanovsky rule from the data of binary subsystems. In addition to vapor pressure measurements densities of investigated solutions were determined.

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Stable binary icosahedral quasicrystals (i-QCs) based on rare earth (RE) and cadmium are typically accessed by solution growth experiments, which operate in very narrow composition and temperature windows. Here, we present a procedure which allows study of peritectic reactions between approximant crystal (AC) phase and liquid yielding i-RECd and exemplify with i-GdCd and ternary variants where Cd is partially replaced by isovalent Zn (i-Gd­(Cd,Zn)) or Mg (i-Gd­(Cd,Mg)), or the 4f element Gd is replaced by nonmagnetic Y (i-(Gd,Y)­Cd). The solubility limits for Zn and Mg substitution are about 10% and 20%, respectively, whereas Gd and Y show a complete solid solution behavior. We find that the peritectic decomposition temperature for i-GdCd is 390 °C, which is decreased when Gd is replaced by Y (i-YCd: 350 °C) and increased when Cd is replaced by Zn (i-Gd­(Cd90Zn10): 440 °C), and especially by Mg (i-Gd­(Cd80Mg20): 520 °C). Whereas substitution decisively alters the decomposition temperature (and hence stability) of the considered i-QCs, the decomposition temperature of the corresponding AC phases remains at around 700 °C. During the investigation of the pseudobinary phase diagrams Gd-(Cd95Zn5), Gd-(Cd90Zn10), and Gd-(Cd80Mg20), faceted i-QCs grains with sizes up to 4 × 4 × 4 mm3 could be isolated.