Variable temperature PXRD investigation of the phase changes during the dehydration of potassium Tutton salts

Morales, Ana C.; Cooper, N.; Reisner, Barbara A.; Devore, T. C.

doi:10.1007/s10973-018-7107-0

Cited by 14 publications

(1 citation statement)

References 24 publications

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“…As illustrated in Table 8, some physical events were analyzed from the DTA curves. At around 361 °C, the KMn/Ni sample thermogram shows a broad endothermal peak characteristic of a phase transition from an anhydrous amorphous structure to an anhydrous crystalline one, similar to the one reported by A. Morales et al [49]. In the KMn/Ni sample, the dehydration process causes the breakdown of numerous intermolecular interactions and makes the amorphous system.…”

Section: Thermal Propertiessupporting

confidence: 82%

Assessing the Novel Mixed Tutton Salts K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 for Thermochemical Heat Storage Applications: An Experimental–Theoretical Study

de Oliveira Neto,

Viana,

Lima

et al. 2023

Molecules

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In this paper, novel mixed Tutton salts with the chemical formulas K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 were synthesized and studied as compounds for thermochemical heat storage potential. The crystallographic structures of single crystals were determined by X-ray diffraction. Additionally, a comprehensive computational study, based on density functional theory (DFT) calculations and Hirshfeld surface analysis, was performed to calculate structural, electronic, and thermodynamic properties of the coordination complexes [MII(H2O)6]2+ (MII = Mn, Ni, and Cu), as well as to investigate intermolecular interactions and voids in the framework. The axial compressions relative to octahedral coordination geometry observed in the crystal structures were correlated and elucidated using DFT investigations regarding Jahn–Teller effects arising from complexes with different spin multiplicities. The spatial distributions of the frontier molecular orbital and spin densities, as well as energy gaps, provided further insights into the stability of these complexes. Thermogravimetry, differential thermal analysis, and differential scanning calorimetry techniques were also applied to identify the thermal stability and physicochemical properties of the mixed crystals. Values of dehydration enthalpy and storage energy density per volume were also estimated. The two mixed sulfate hydrates reported here have low dehydration temperatures and high energy densities. Both have promising thermal properties for residential heat storage systems, superior to the Tutton salts previously reported.

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Section: Thermal Propertiessupporting

confidence: 82%

Assessing the Novel Mixed Tutton Salts K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 for Thermochemical Heat Storage Applications: An Experimental–Theoretical Study

de Oliveira Neto,

Viana,

Lima

et al. 2023

Molecules

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Tutton salt (NH4)2Zn(SO4)2(H2O)6: thermostructural, spectroscopic, Hirshfeld surface, and DFT investigations

de Oliveira Neto,

Viana,

Abreu

et al. 2024

J Mol Model

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Context Ammonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h. Methods Computational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed. Graphical abstract

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Mixed tutton salts K2Mn0.15Co0.85(SO4)2(H2O)6 and K2Mn0.16Zn0.84(SO4)2(H2O)6 for applications in thermochemical devices: experimental physicochemical properties combined with first-principles calculations

de Oliveira Neto,

da Silva,

Alves

et al. 2024

J Mater Sci

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Variable temperature PXRD investigation of the phase changes during the dehydration of potassium Tutton salts

Cited by 14 publications

References 24 publications

Assessing the Novel Mixed Tutton Salts K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 for Thermochemical Heat Storage Applications: An Experimental–Theoretical Study

Assessing the Novel Mixed Tutton Salts K2Mn0.03Ni0.97(SO4)2(H2O)6 and K2Mn0.18Cu0.82(SO4)2(H2O)6 for Thermochemical Heat Storage Applications: An Experimental–Theoretical Study

Tutton salt (NH4)2Zn(SO4)2(H2O)6: thermostructural, spectroscopic, Hirshfeld surface, and DFT investigations

Mixed tutton salts K2Mn0.15Co0.85(SO4)2(H2O)6 and K2Mn0.16Zn0.84(SO4)2(H2O)6 for applications in thermochemical devices: experimental physicochemical properties combined with first-principles calculations

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