gel growth
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2021 ◽  
Vol 11 (1) ◽  
Jolanta Prywer ◽  
Rafał Kruszyński ◽  
Marcin Świątkowski ◽  
Andrzej Soszyński ◽  
Dariusz Kajewski ◽  

AbstractIn this paper, we present the first experimental evidence of the piezoelectric nature of struvite (MgNH4PO4·6H2O). Using a single diffusion gel growth technique, we have grown struvite crystals in the form of plane parallel plates. For struvite crystals of this shape, we measured the piezoelectric coefficients d33 and d32. We have found that at room temperature the value of piezoelectric coefficient d33 is 3.5 pm/V, while that of d32 is 4.7 pm/V. These values are comparable with the values for other minerals. Struvite shows stable piezoelectric properties up to the temperature slightly above 350 K, for the heating rate of 0.4 K/min. For this heating rate, and above this temperature, the thermal decomposition of struvite begins, which, consequently, leads to its transformation into dittmarite with the same non-centrosymmetric symmetry as in case of struvite. The struvite-dittmarite transformation temperature is dependent on the heating rate. The higher the heating rate, the higher the temperature of this transformation. We have also shown that dittmarite, like struvite exhibits piezoelectric properties.

Gels ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 11
Akitsugu Kawabata ◽  
Takao Yamamoto ◽  
Hiroki Shinoda ◽  
Kazuto Yoshiba ◽  
Yoshiharu Toyama ◽  

Plasma is regarded as a solution of precursor polymers specifically transformed to gel-forming polymers by a reaction with initiators. We developed a theory for the gel growth dynamics of plasma induced by contact with a source of gelators that are yielded by the initiation. In developing the theory, we combined the Ginzburg–Landau type dynamics with the gelator diffusion dynamics expressed by the moving boundary picture. The theory predicts the crossover of the rate-limiting process in the time course of the thickness of the gel layer X from the energy-limited process expressed by X∼t to the diffusion-limited process expressed by X∼t, where t is the time elapsed from when the plasma comes into contact with the source of gelators. A demonstration experiment was performed by placing a tissue factor coating plate as the initiator in plasma. Log–log plot of X vs. t showed a crossover as predicted by the theory, and the parameters characterizing plasma were determined.

2021 ◽  
Vol 13 (1) ◽  
pp. 7-14
C. Muthuselvi ◽  
I. Ilakkiya ◽  
I. Parameswar ◽  
A. Alagumari

Mohammad Misbah Khunur ◽  
Dini Tri Wahyuni ◽  
Gigih Wahyu Kurniawan ◽  
Yuniar Ponco Prananto

2020 ◽  
Vol 101 ◽  
pp. 109724 ◽  
Lulu Lu ◽  
Guolun Dai ◽  
Liuliu Yan ◽  
Lijin Wang ◽  
Lingnan Wang ◽  

CrystEngComm ◽  
2020 ◽  
Vol 22 (36) ◽  
pp. 5954-5960
Ibrahim Hany ◽  
Bryant Kanies ◽  
Ge Yang

An underutilized, but highly advantageous, method of growing functional-single-crystals, the gel-growth technique, is highlighted. Large nonlinear optical crystals, BCHT, were grown and their dehydration phase-transformation to β-BTC were studied.

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 443 ◽  
Omar Velásquez-González ◽  
Camila Campos-Escamilla ◽  
Andrea Flores-Ibarra ◽  
Nuria Esturau-Escofet ◽  
Roberto Arreguin-Espinosa ◽  

A gel can be considered to be a two-phase (liquid and solid) system, which lacks flow once it reaches a stationary state. The solid phase is usually a tridimensional polymeric mesh, while the liquid phase is usually found in three forms: contained in great cavities, retained in the capillary pores between micelles, or adsorbed on the surface of a micelle. The influence of the use of gels in crystal growth is diverse and depends on the type of gel being used. A decrease in solubility of any solute in the liquid may occur if the solvent interacts extensively with the polymeric section, hence, the nucleation in gels in these cases apparently occurs at relatively low supersaturations. However, if the pore size is small enough, there is a possibility that a higher supersaturation is needed, due to the compartmentalization of solvents. Finally, this may also represent an effect in the diffusion of substances. This review is divided into three main parts; the first evaluates the theory and practice used for the obtainment of polymorphs. The second part describes the use of gels into crystallogenesis of different substances. The last part is related to the particularities of protein crystal polymorphism, as well as modern trends in gel growth for high-resolution X-ray crystallography.

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 89 ◽  
Jolanta Prywer ◽  
Lesław Sieroń ◽  
Agnieszka Czylkowska

In this article, we report the crystallization of struvite in sodium metasilicate gel by single diffusion gel growth technique. The obtained crystals have a very rich morphology displaying 18 faces. In this study, the habit and morphology of the obtained struvite crystals are analyzed. The crystals were examined and identified as pure struvite by single X-ray diffraction (XRD). The orthorhombic polar noncentrosymmetric space group Pmn21 was identified. The structure of the crystal was determined at a temperature of 90 K. Our research indicates a lack of polymorphism, resulting from the temperature lowering to 90 K, which has not been previously reported. The determined unit cell parameters are as follows a = 6.9650(2) Å, b = 6.1165(2) Å, c = 11.2056(3) Å. The structure of struvite is presented here with a residual factor R1 = 1.2% at 0.80 Å resolution. We also present thermoanalytical study of struvite using thermal analysis techniques such as thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA).

2018 ◽  
Vol 87 ◽  
pp. 98-109 ◽  
Deyu Kong ◽  
Senle Huang ◽  
David Corr ◽  
Yang Yang ◽  
Surendra P. Shah

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