Ionic Volume Research Articles

Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study.

Nickel orthovanadate is a promising material with potential applications in energy storage and photocatalytic devices. The crystal structure of Ni3V2O8 at 299 (3) K and 1323 (8) K was studied using X-ray powder diffraction. The sample was a single-phase orthorhombic kagome-staircase-Ni3(VO4)2-type structure (space group Cmca) at both temperatures. The phase purity and morphology was studied using energy-dispersive X-ray spectroscopy and scanning electron microscopy. The refined unit-cell parameters at 299 (3) K are a = 5.93384 (4) Å, b = 11.38318 (7) Å and c = 8.23818 (5) Å, and at 1323 (8) K are a= 6.02077 (7) Å, b = 11.48838 (7) Å and c = 8.32611 (9) Å. The obtained results indicate thermal expansion anisotropy, with a largest expansivity along a. Variations in Ni-O and V-O bonds with temperature are observed. The variation in the Ni-O bond is about one order higher in magnitude than that of the V-O bond, signifying the high rigidity of V-O bonds. The unit-cell size variations with rising effective ionic volume of the divalent A ion in the A3B2O8 family [A = Ni, Mg, Zn, Co, Mn (experimental data) and also A = Cu, Cd (theoretical data), B = V or As] are analyzed. Based on experimental and theoretical data, trends within the family are observed and the unit-cell size for reported solid solution of nickel (87%) and copper (13%) mixture in (Ni1-xCux)3V2O8 are predicted. Predictions are also provided for some hypothetical A3B2O8 ternary compound and solid solutions.

General Trends in the Compression of Glasses and Liquids

The present work relates the isothermal volumes of silicate glasses and melts to the combined ionic volumes of their chemical constituents. The relation is an extension of a relation that has already been established for crystalline oxides, silicates, alumosilicates, and other materials that have O2− as a constituent anion. The relation provides constraints on bond coordination, indicates pressure-induced changes in coordination in melts and glasses and interatomic distances, and quantifies the extent of transitory regions in pressure-induced coordination changes.

Effect of thermal pre‐compressing on ionic conductivity and mechanical properties of PEO‐based solid‐state electrolytes

AbstractPolyethylene oxide (PEO)‐based solid polymer electrolytes are regarded as promising electrolyte materials because of their safety and flexibility. However, low ionic conductivity at ambient temperature and poor mechanical properties have been a hindrance to its development. In this work, we thermally compressed the PEO‐based electrolytes and explored the ionic conductivity, mechanical performance, free volume, and thermal properties of the electrolyte under different thermal pre‐compressing strains (TPC‐strains). The results show that TPC‐strain can significantly improve the ionic conductivity, in‐plane strength, stiffness, and cell specific capacity as well as the mechanical integrity of solid polymer electrolytes within the battery environment. However, it also results in a reduction in the modulus and stiffness of the SPEs in the through‐plane. In particular, applying a TPC‐strain of 10%–20% to the SPEs by thermal compressing may be a suitable option, which can increase the ionic conductivity of the through‐plane to a factor of 3.4 compared with the uncompressed electrolyte, and increase the in‐plane strength by up to 141%, resulting in better mechanical integrity during charging/discharging processes. At the same time, the compression modulus can be maintained at 80% or higher.

Ionic-liquid/Carbowax 20 M functionalized capsule phase microextraction platform for the extraction of phosphodiesterase-5 inhibitors from human serum and urine prior to their determination by LC–MS

Capsule phase microextraction (CPME) is an efficient bioanalytical technique that streamlines the sample preparation by integrating the filtration and stirring mechanism directly into the device. A novel composite sorbent designed to be selective towards the target analytes consisting of mixed-mode sorbent chemistry synthesized by sol–gel technology is found promising and superior to the conventional C18 sorbents. Herein we describe the encapsulation of an ionic liquid (IL)/Carbowax 20M-functionalized sol–gel sorbent (sol–gel IL/Carbowax 20 M) in the lumen of porous polypropylene tubes for the capsule phase microextraction of three phosphodiesterase-5 inhibitors namely avanafil, sildenafil, and tadalafil in human serum and urine samples. The CPME device was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR). The experimental parameters of CPME procedure (e.g. sample pH and ionic strength, extraction time, stirring rate, elution solvent and volume) were carefully optimized to achieve the highest possible extraction efficiency for the analytes. Method validation was conducted in terms of precision, linearity, accuracy, matrix effect, lower limits of quantification, and limits of detection (LOD). The method linearity was investigated in the range of 50–1000 ng mL−1 for all analytes while the precision was less than 11.8 % in all cases. For all analytes, the LOD values were 17 ng mL−1. The IL/CW 20M-functionalized microextraction capsules could be reused at least 25 times both for urine and serum samples. The green character and the applicability of the proposed method were evaluated using the ComplexGAPI and BAGI indexes. The optimized CPME protocol exhibited reduced consumption of organic solvent and generation of waste, cost-effectiveness, and simplicity. Finally, the proposed method was successfully applied to the analysis of sildenafil in human urine after administration of drug-containing formulation.

Subsurface Profiling of Ion Migration and Swelling in Conducting Polymer Actuators with Modulated Electrochemical Atomic Force Microscopy.

Understanding the dynamics of ion migration and volume change is crucial to studying the functionality and long-term stability of soft polymeric materials operating at liquid interfaces, but the subsurface characterization of swelling processes in these systems remains elusive. In this work, we address the issue using modulated electrochemical atomic force microscopy as a depth-sensitive technique to study electroswelling effects in the high-performance actuator material polypyrrole doped with dodecylbenzenesulfonate (Ppy:DBS). We perform multidimensional measurements combining local electroswelling and electrochemical impedance spectroscopies on microstructured Ppy:DBS actuators. We interpret charge accumulation in the polymeric matrix with a quantitative model, giving access to both the spatiotemporal dynamics of ion migration and the distribution of electroswelling in the electroactive polymer layer. The findings demonstrate a nonuniform distribution of the effective ionic volume in the Ppy:DBS layer depending on the film morphology and redox state. Our findings indicate that the highly efficient actuation performance of Ppy:DBS is caused by rearrangements of the polymer microstructure induced by charge accumulation in the soft polymeric matrix, increasing the effective ionic volume in the bulk of the electroactive film for up to two times the value measured in free water.

Heat capacities and role of defects in ion transfer of quinuclidinium hexafluorophosphate plastic crystal

To study the phase behavior and role of defects in the ion conduction of a well-investigated plastic crystal electrolyte, we measured the low-temperature heat capacities of quinuclidinium hexafluorophosphate ([HQ]PF6) plastic crystal and the defects of pure [HQ]PF6 and its mixtures containing lithium ions and chloride ions. The heat capacities of the pure material show two solid‒solid phase transitions at room temperature and a low temperature. Positron annihilation lifetime spectroscopy (PALS) revealed the phase dependence of the defect size for both the pure material and the mixtures. The defects in these two mixtures expand largely to approximately 2 (with Li+) and 2.5 (with Cl−) times larger than those in the pure material. The relationships between the ionic conductivity and vacancy volume of the pure material and the mixtures obey the Cohen−Turnbull free volume model, which is also phase dependent. This work help elucidate defect-assisted ion transfer in organic ionic plastic crystals.

Crystal Structure Complexity and Approximate Limits of Possible Crystal Structures Based on Symmetry-Normalized Volumes.

Rules that control the arrangement of chemical species within crystalline arrays of different symmetry and structural complexity are of fundamental importance in geoscience, material science, physics, and chemistry. Here, the volume of crystal phases is normalized by their ionic volume and an algebraic index that is based on their space-group and crystal site symmetries. In correlation with the number of chemical formula units Z, the normalized volumes exhibit upper and lower limits of possible structures. A bottleneck of narrowing limits occurs for Z around 80 to 100, but the field of allowed crystalline configurations widens above 100 due to a change in the slope of the lower limit. For small Z, the highest count of structures is closer to the upper limit, but at large Z, most materials assume structures close to the lower limit. In particular, for large Z, the normalized volume provides rather narrow constraints for the prediction of novel crystalline phases. In addition, an index of higher and lower complexity of crystalline phases is derived from the normalized volume and tested against key criteria.

Finite ion size effects on electrophoresis of a dielectric surfactant-laden droplet in a non-dilute electrolyte

The ion steric repulsion and ion-solvent interactions, due to the finite size of ions, are analyzed for electrophoresis of a droplet in a non-dilute electrolyte in which the ionic volume fraction is O(0.01). In this study, the viscosity of the suspension medium is considered to be dependent on the local ionic volume fraction. The electrochemical potential of the finite-sized ions is modified to take into account the steric interactions. The impact of the Marangoni stress due to the non-uniform distribution of the non-ionized surfactant is taken into account. Governing equations are solved under a weak applied field consideration. At a lower range of surface charge density, the mobility is found to increase with the droplet viscosity, in which the Marangoni stress is found to enhance the mobility. The counterion saturation created by the ion steric interaction attenuates the screening of the surface charge and hence, enhances the mobility. However, the enhanced viscosity of the medium for the non-dilute electrolyte reduces the mobility and this reduction is higher in a monovalent electrolyte as compared to a multivalent electrolyte. The standard model shows a singularity in mobility when the surface potential is varied. However, the dependence of mobility on surface potential in the modified model is found to exhibit a smooth variation.

Concentrated aqueous solutions of multivalent macroions enhance the electrical double layer capacitance and differential capacitance of a planar supercapacitor

The electrostatic properties of the ionic cloud, or electrical double layer, neutralizing a charged electrode are relevant to improve the storage of electrical energy and the efficiency of supercapacitors and/or batteries using coulombic fluids. In this work, we study the microscopic profiles of charged particles, integrated surface charge density, and the mean electrostatic potential associated to a pair of infinite parallel plates uncharged or, else, with opposite charge, in the presence of a salt-free aqueous solution constituted by big positive macroions and small anions, which interact via an explicit electrostatic coulombic potential and are dissolved in an implicit solvent. The particle profiles and the integrated surface charge density associated to Monte Carlo simulations and integral equations theory display an oscillatory or non-monotonic behaviour producing the phenomena of charge inversion and charge reversal. These phenomena are not predicted by the non-linear Poisson-Boltzmann equation, which highlights the importance of ion correlations and ionic volume excluded effects. The phenomenon of surface charge amplification is observed near the point of zero charge, which is yielded by the particle size-asymmetry. For a fixed concentration of macroions, a monotonic increase of the mean electrostatic potential difference between the charged parallel plates is predicted by simulations and theories as a function of the electrodes' charge. For a fixed surface charge density, the capacitance of the parallel plates capacitor increases when the ionic strength of the macroion's solution increases. A concavity inversion and an augment of the differential capacitance is also observed for an electrode near the point of zero charge as function of the macroion's concentration.

Isothermal compressibility, internal pressure studies of aqueous rare earth nitrate solutions at 298.15 K: An attempt to estimate ionic radii and understand inner– and outer–sphere exchange water structural interactions

In this communication, we report our analysis and results concerning the determination of ionic radii in aqueous solution phase for Lanthanum (La+3), Neodymium (Nd+3), Erbium (Er+3) and Ytterbium (Yb+3) ions in presence of nitrate (NO3-) anion at 298.15 K. The literature data for density, adiabatic compressibility, and specific heat capacity of solutions at constant pressure have been used to compute isothermal compressibility, internal pressure of solutions in limiting concentration range. The apparent molar isothermal compressibility of electrolytes and hydration numbers have been obtained. The electrostriction for rare earth cations and intrinsic volumes have been calculated using thermodynamic equations. The ionic radii of cations have been obtained using the ionic partial molar volume data of NO3- ions and the results are compared with those obtained for rare earth chlorides. The two series affect is also observed for ionic radii and internal pressure. The results have been explained on the basis of water structural effects due to electrostatic field and water dipole interaction between the inner– and outer–sphere water exchange reaction.

Systematics of Crystalline Oxide and Framework Compression

A universal equation of state of solids is one of the far goals of condensed matter science. Here, it is shown that within pressures of 2–100 GPa, the compression of oxides and oxide-based networks follows a linear relation between the molar volume and the combined ionic volume that is based on the pressure-dependent crystal radii at any pressure. This relation holds for simple and complex oxides and modified networks such as alumosilicates, beryllosilicates, borates, and empty zeolites. Available compression data for halides and metal-organic frameworks are also consistent with this relation. Thus, the observed relation also serves as a measure for pore-space filling in cage structures.

Characterizations of structural, optical, and dielectric properties of oxynitride perovskites ACa0.2M0.8O2.6N0.4 (A= Sr, Ba; M = Nb, Ta)

Perovskite-type oxynitrides ACa0.2M0.8O2.6N0.4 (A = Sr, Ba; M = Nb, Ta) were synthesized via the ammonolytic reaction between A5M4O15 and CaCl2, where the Ca2+ insertion and O2−/N3− substitution occurred cooperatively. In terms of the average structure, SrCa0.2Nb0.8O2.6N0.4 and SrCa0.2Ta0.8O2.6N0.4 belong to the orthorhombic Pnma space group, and BaCa0.2Nb0.8O2.6N0.4 and BaCa0.2Ta0.8O2.6N0.4, the primitive cubic Pm3‾m group. The comparison between the experimental lattice volume and the summed ionic volume suggested that ACa0.2M0.8O2.6N0.4 have higher degrees of ionicity than AM'0.2M0.8O3−xNx (M′ = Li, Mg, Mn), but are more covalent than ANa0.2M0.8O2.8N0.2. Despite the significant mismatches of size and charge between Ca2+ and Nb5+ (or Ta5+), no cation ordering was detected on the octahedral site. On the other hand, the O/N distribution appeared to depend on the bonding geometry around the anion sites in a way N favors the straighter bonding connectivity of M−N−M. The band gap energies of ACa0.2M0.8O2.6N0.4 were estimated to be 1.9–2.25 eV depending on A and M. The band gaps and color properties of AMO2N and AM'0.2M0.8O3−xNx (A = Sr, Ba; M = Nb, Ta; M′ = Li, Na, Mg, Ca, Mn) are compared. Thermogravimetry and differential scanning calorimetry were conducted in the air to assess the oxynitride stability. The electrical behaviors were studied by the equivalent circuit analysis of the impedance spectrum using compacted polycrystalline specimens, where BaCa0.2Ta0.8O2.6N0.4 was found to possess a bulk dielectric constant of 4550 along with an electrical conductivity of ≈10−6 S/cm at 27 °C. It remains, however, necessary to assess the extrinsic effects arising from the non-ideal sintering to interpret thoroughly the electrical property of BaCa0.2Ta0.8O2.6N0.4.

Niobium sulfide nanocomposites as cathode materials for all-solid-state lithium batteries with enhanced electrochemical performance.

All-solid-state lithium batteries coupled with transition metal sulfide cathodes have gained significant attention due to their high energy density and exceptional safety. However, there are still critical challenges impeding their practical application, such as limited capacity delivery, weak ionic reaction kinetics and volume expansion. Herein, an a-NbS4/20%VGCF@15%Li7P3S11 nanocomposite cathode material is employed in all-solid-state batteries. A certain proportion of VGCF is introduced into crystalline NbS4 in order to mitigate the volume expansion and improve electronic conductivity. At the same time, a-NbS4/20%VGCF is in situ coated with a Li7P3S11 solid electrolyte layer to achieve an intimate interfacial contact. The obtained a-NbS4/20%VGCF@15%Li7P3S11 nanocomposite exhibits a remarkable electronic conductivity (1.0 × 10-1 S cm-1) and ionic conductivity (5.5 × 10-4 S cm-1), which are improved by five and two orders of magnitude compared to those of NbS4, respectively. The Li/Li6PS5Cl/a-NbS4/20%VGCF@15%Li7P3S11 battery exhibits a high initial discharge capacity of 1043.25 mA h g-1 at 0.1 A g-1. Even at 0.5 A g-1, it could provide a reversible capacity of 403.2 mA h g-1 after 500 cycles. This work provides a promising cathode material for all-solid-state lithium batteries with improved ionic/electronic conductivity, high reversible capacity and superior cycling stability.

Exploiting the potential of fabric phase sorptive extraction for forensic food safety: Analysis of food samples in cases of drug facilitated crimes

Drug-facilitated crimes (DFCs) entail the use of a single drug or a mixture of drugs to render a victim unable. Traditionally, biological samples have been gathered from victims and conducting analysis to establish evidence of drug administration. Nevertheless, the rapid metabolism of various drugs and delays in analysis can impede the identification of such substances. For this, the present article describes a rapid, sustainable, highly efficient and miniaturized protocol for the identification and quantification of three sedative-hypnotic drugs namely diazepam, chlordiazepoxide and ketamine in alcoholic beverages and complex food samples (cream of biscuit, flavoured milk, juice, cake, tea, sweets and chocolate). The methodology involves utilizing fabric phase sorptive extraction (FPSE) to extract diazepam (DZ), chlordiazepoxide (CDP), and ketamine (KET), Subsequently, the extracted sample are subjected to analysis using gas chromatography-mass spectrometry (GC–MS). Several parameters, including type of membrane, pH, agitation time and speed, ionic strength, sample volume, elution volume and time, and type of elution solvent, were screened and thoroughly optimized. Sol-gel Carbowax 20M (CW-20M) has demonstrated most effective extraction efficiency for the target analytes among all evaluated membranes. Under optimal conditions, the method displayed linearity within the range of 0.3–10 µg mL−1 (or µg g−1), exhibiting a coefficient of determination (R2) ranging from 0.996 to 0.999. The limits of detection (LODs) and limits of quantification (LOQs) for liquid samples ranging between 0.020 and 0.069 µg mL−1 and 0.066–0.22 µg mL−1, respectively. Correspondingly, the LODs for solid samples ranged from 0.056 to 0.090 µg g−1, while the LOQs ranged from 0.18 to 0.29 µg g−1. Notably, the method showcased better precision, with repeatability and reproducibility both below 5% and 10%, respectively. Furthermore, the FPSE-GC–MS method proved effective in determining diazepam (DZ) in forensic food samples connected to drug-facilitated crimes (DFCs). Additionally, the proposed method underwent evaluation for its whiteness using the RGB12 algorithm.

Numerical model supplemented by thin-layer analysis for diffusiophoresis of a particle incorporating finite ion size effects

The impact of finite-sized ions on the diffusiophoresis of a charged colloid subjected to a concentration gradient of electrolyte solution consisting monovalent or multivalent ionic species, is studied. In diffusiophoresis, the ion concentration is of O(1M). In this non-dilute electrolyte solutions, the ion–ion steric interaction is important. We have adopted the Boublik–Mansoori–Carnahan–Starling–Leland (BMCSL) model to account for the ion steric interactions and the Batchelor–Green expression for the relative viscosity of suspension. We have solved the standard model numerically considering ions as point charge (PNP-model), the modified Nernst–Planck equations incorporating the ion steric interaction with constant viscosity (MNP-model), and modification of the MNP-model by incorporating the viscosity variation with the ionic volume fraction (MNPV-model). Semi-analytical expressions for mobility based on a linear perturbation technique under a thinner Debye length is presented for PNP- and MNP-models. In the MNP-model, counterion saturation in the Debye layer due to the ion steric interaction enhances the surface potential by attenuating the shielding effect, diminishes the surface conduction, and magnifies the induced electric field. These in combination create a larger mobility at a thinner Debye length compared with the PNP-model. This increment in mobility attenuates when the MNPV-model is considered. The MNPV-model is more appropriate to analyze the finite ion size effects, and it is found to yield the mobility values more close to the experimental data compared with the MNP- and PNP-model. The semi-analytical expressions for mobility based on the PNP- and MNP-models agree with the corresponding exact numerical solutions when the surface potential is in the order of thermal potential. However, a large discrepancy between the simplified expression and the exact numerical results is found for a concentrated electrolyte in which the induced electric field is large.

Simulation Study on Heat Generation Characteristics of Lithium-Ion Battery Aging Process

Lithium-ion battery heat generation characteristics during aging are crucial for the creation of thermal management solutions. The heat generation characteristics of 21700 (NCA) cylindrical lithium-ion batteries during aging were investigated using the mathematical model that was created in this study to couple electrochemical mechanisms, heat transfer, and aging loss. These findings indicate that, at the same operating current, the heat generation power of the cell increased significantly with battery aging. This increase was primarily due to the energy loss caused by the growth of the solid–electrolyte interface (SEI) and a reduction in the negative porosity and other physical characteristics of the SEI, such as its ionic conductivity and molar volume, which also had an impact on the heat generation power. By investigating the variations in battery heat generation in different aging modes, the electrochemical mechanisms underlying the effects of aging on battery heat generation can be comprehended in depth.

Lithium-Ion and Chloride-Ion Transfer in Chiral and Racemic 3-Hydroxyquinuclidinium Perchlorate: Influence of Defects and a Mixed Plastic Crystal Matrix

Organic ionic plastic crystals (OIPCs) are promising solid electrolytes. To observe the effect of defects and a mixed OIPC matrix on ionic conductivity, lithium-ion transfer and chloride-ion transfer in chiral and racemic (+/±)-3-hydroxyquinuclidinium perchlorate plastic crystals were studied. The pure chiral material and racemic mixture and their corresponding doped mixtures showed different thermal behaviors. Powder X-ray diffraction revealed that the cubic crystal structure appeared in both the high-temperature phase of the pure chiral material and the whole temperature range for the racemic system. Solid-state nuclear magnetic resonance spectra indicated the possible ion mobility of the two undoped matrices. The lithium-ion conductivity in the chiral material (above −10 °C) and racemic mixture (in the whole temperature region) increased 2.5–3 orders of magnitude, while the chloride-ion conductivity in the chiral material only increased obviously above 50 °C. Positron annihilation lifetime spectroscopy demonstrated the dependence of ionic conductivity on defect volumes of the pure chiral material and its doped mixtures, and the defects of the doped mixtures expanded largely. The ionic conductivity and defect volume of the doped mixtures containing lithium ions and chloride ions qualitatively obeyed the Cohen–Turnbull free volume theory.

Numerical study supplemented with simplified model on electrophoresis of a hydrophobic colloid incorporating finite ion size effects and ion-solvent interactions.

We consider a modified electrokinetic model to study the electrophoresis of a hydrophobic particle by considering the finite sized ions. The mathematical model adopted in this study incorporates the ion steric repulsion, ion-solvent interactions as well as Maxwell stress on the electrolyte. The dielectric permittivity and viscosity of the electrolyte is considered to vary with the local ionic volume fraction. Based on this modified model for the electrokinetics we have analyzed the electrophoresis in a single as well as mixture of electrolytes of monovalent and non- electrolytes. The dependence of viscosity on local ionic volume fraction modifies the hydrodynamic drag as well as diffusivity of ions, which are ignored in existing studies on electrophoresis. A simplified model for electrophoresis of a hydrophobic particle incorporating the ion steric repulsion and ion-solvent interactions is developed based on the first-order perturbation on applied electric field. This simplified model is established to be efficient for a Debye layer thinner than the particle size and a smaller range of slip length. This model can be implemented for any number of ionic species as well as non- electrolytes. It is established that the ion steric interactions and dielectric decrement creates a counterion saturation in the Debye layer leading to an enhanced mobility compared to the standard model. However, experimental data for non-dilute cases often under predicts the theoretically determined mobility. The present modified model fills this lacuna and demonstrate that the consideration of finite ion size modifies the medium viscosity and hence, ionic mobility, which in combination lowers the mobilityvalue.

Determination of Trace Sudan I in Spices by Novel, Green Ionic Liquid Based Microextraction with Spectrophotometry

A new, green method has been developed for the determination of the trace Sudan I prior to spectrophotometric determination. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), was used as an extraction solvent for Sudan I. The analytical parameters which influence the recovery of Sudan I, such as the pH, ionic liquid volume, and sample volume, were optimized. Sudan I was quantitatively extracted at pH 6.0. The influences of matrix components upon the analysis were investigated. The limits of detection (LOD) and quantification (LOQ) were 0.039 µg/L and 0.108 µg/L, respectively. The method was employed to determine Sudan I in food.

Local stress within a granular molecular solvent matrix, a mechanism for individual ion hydration

• Individual ion hydration values are estimated from a matrix of full hydration values for complete salts. • Ionic volume relative to the volume of water shown to dictate hydration requirements. • Solutes may conceptually behave as substitutional defects in a water matrix, inducing tensile or compressive stresses. • This model may advance the understanding of solute activity, ion diffusion, solution viscosity, and the Hofmeister series. The activity of water is important in many natural systems and directed processes. To better understand water activity, the hydration of individual ions is approximated for a recently developed speciation-based solution model. A matrix of values for hydration of complete salts (anion and cation) was used as source data to calculate individual ion hydration values. Some electrolytes were excluded from calculations of individual ion hydration due to the prevalence of ion pairing and resulting liberation of water upon ion pairing. Evaluation of the periodic trends emerging from individual ion hydration values suggests that ionic volume, relative to the volume of molecular water, dictates both modeled hydration requirements (related to vapor–liquid-equilibrium-derived activity) as well as properties historically described by hydrodynamic radius (ion diffusion and solution viscosity). When water is conceptualized as a granular three-dimensional matrix, solutes may function as substitutional defects (dilation or constriction) inducing local compressive or tensile stress. These results have implications on the mechanism of the Hofmeister series and series reversals.