Increase In Ionic Radius Research Articles

Investigations of Mechanisms Leading to Capacity Differences in Li/Na/K-Ion Batteries with Conversion-Type Transition-Metal Sulfides Anodes.

Conversion-type transition-metal sulfides (CT-TMSs) have been extensively studied as the anode of Li/Na/K-ion batteries due to their high theoretical capacity. An issue with the use of the material in the battery is that a large capacity difference is commonly observed. However, the underlying mechanism leading to the problem is still unknown. Here, the large capacity difference mechanisms of CT-TMSs anodes in the Li/Na/K-ion storage are elucidated, which arises from the difference in conversion degree and size of conversion products. Specifically, the increase in ionic radius will cause the increase in insertion-reaction ion diffuse energy barrier and conversion-reaction Gibbs free energies of phase transformation to decrease reaction kinetics, which causes a decrease in conversion degree and an increase in size of conversion products, thus leading to reduction in capacity. The increase in size and the decrease in the amount of conversion products inevitably reduce the amount of spin-polarized electrons injection into Fe and corresponding ions storage amount into sulfides during the ion-electron decoupling storage, thus reducing the capacity. The research clarifies the capacity difference mechanisms of CT-TMSs anodes in Li/Na/K storage, providing valuable insights for designing Li/Na/K storage high-capacity anodes.

Evaluating the significance of rare earth and iron doping on structure-property of lead titanate

The samples (Pb0.8Ln0.2 Fe0.2 Ti0.8O3, (Ln= La, Nd, Sm, Gd)) were synthesized successfully by mixed oxide method. A significant reduction in tetragonality is observed with the modification of structure. The grain size from FESEM study was observed to be decreasing with increase in ionic radii of rare earth ions. Specifically, the dielectric constant is found to be maximum for the Sm-doped sample. Conductivity studies at varying temperature and frequencies reveal the NTCR behaviour of these samples. In Sm, Nd and Gd doped samples, tunnelling of small polarons is responsible for conduction process whereas for La doped sample, the conduction process is mediated through the combined effect of small polaron tunnelling and bipolaron hopping. The Sm-doped sample exhibits highest remanent polarization. All the results of this comprehensive study provide valuable insights into the effect of dopant ions on various properties of the studied materials, paving the way for device applications.

Manipulating and investigating the room-temperature magnetic memory phenomenon: The impact of rare-earth ion doping on nickel oxide nanoparticles

This study investigates the relationship between point defect density and magnetic properties in nickel oxide (NiO) nanoparticles (NPs). Specifically, we explore the effects of 0.5 % trivalent rare-earth ion (RE3+: Ce3+, Pr3+, Nd3+, Sm3+, and Dy3+) doping on NiO NPs, considering the influence of RE3+ ionic radius on structural modulation and magnetic properties. Our findings reveal important trends: increased microstrain (0.08 %–0.17 %) and decreased crystalline size (36–17 nm) with increasing ionic radius (r = 0.91 to 1.01 Å), along with a preference for growth along the (1 1 1) plane over (2 0 0). Additionally, multivalent point defects increase with the increase of ionic radius. Substituting Ni2+ site with RE3+ ion promotes nearest-neighbor weak ferromagnetic interaction over next-nearest-neighbor strong antiferromagnetic (AF) interaction. This leads to a redshift of two magnons (2 M) frequency by 50 cm−1 and enhanced room temperature (RT) magnetization (0.23–0.43 emu/g) with increasing ionic radius. Ce-doped NiO (r = 1.01 Å) shows the smallest crystalline size (17 nm), maximum 2 M redshift, and enhanced RT magnetization (0.43 emu/g) based on interacting bound magnetic polaron model. Ce-, Pr-, Nd-, and Sm-doped NiO NPs exhibit RT magnetic memory effects, while Dy-doped NiO NPs (r = 0.912 Å) display AF properties. Our analysis provides valuable insights for designing RT magnetic memory materials with tailored properties through suitable RE3+ ion substitutions.

New zircon-manganites of lanthanum and alkali metals

Zircon-manganites of the composition LaMeI2ZrMnO6 (MeI – Li, Na, K). were synthesized using the ceramic technology method in the range of 800-1200°C by the interaction of lanthanum (III) oxides and lithium, sodium and potassium carbonates (analytical grade). Using X-ray diffraction methods, it was established that all synthesized zircon-manganites crystallize in a cubic system with the following lattice parameters: LaLi2ZrMnO6 – а = 16,26 ±0,02 Å; V0 = 4300,93 ±0,06 Å3; Z = 6; V° elem cell = 716,82 ± 0,02 Å3; r x-ray. = 5,49 g/сm3; r picn. = 5,42 ± 0,06 g/сm3; LaNa2ZrMnO6 – а = 16,85 ± 0,02Å; V0 = 4785,46 ± 0,02 Å3; Z = 6; V° elem cell = 795,58 ± 0,02 Å3; r x-ray. = 5,35 g/сm 3; r picn. = 5,30 ± 0,04 g/сm 3; LaK2ZrMnO6 – а = 17,45 ± 0,03 Å; V0 = 5318,85 ±0,09 Å3; Z = 6; V° elem cell = 885,81 ± 0,02 Å3; r x-ray. = 5,16 g/сm 3; r picn. = 5,08 ± 0,02 g/сm 3. It has been established that with an increase in ionic radii in the Li®Na®K series, the values of the parameter “a” and the volumes of lattices and unit cells of zircon-manganites increase.

Structural phase transitions in multicomponent La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) oxides

AbstractIn this work, the influence of compositional complexity on the structural and thermal properties of multicomponent rare‐earth ortho‐niobates from the La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) series was investigated. Based on X‐ray powder diffraction studies using synchrotron radiation, it was found that all tested materials were pure single‐phase compositions and showed stability in the monoclinic I2/c crystal structure at room temperature. High‐temperature X‐ray powder diffraction studies and dilatometry studies confirmed the presence of a structural phase transition between low‐temperature (I2/c) and high‐temperature (I41/a) polymorphs. The structural phase transition temperatures are between 676°C and 701°C. Interestingly, despite their compositional complexity, the structural phase transition temperature behaves similarly to conventional ortho‐niobates, that is, it depends on the radius of the A‐cation; that is, as the ionic radius increases, the phase transition temperature decreases. The transition has been categorized as a second‐order phase transition based on the observed relationship between the Landau order parameter and spontaneous strain. The coexistence of the tetragonal and monoclinic phases has been seen in all compositions around the temperature of the structural phase transition. The presence of two orientation states in the monoclinic structure leads to the so‐called spontaneous strain, which consists of longitudinal (u) and shear (v) strain components. The values of these strains at 300°C range between 2.42 and 2.58 × 10−2 for longitudinal, 2.98 and 3.04 × 10−2 for shear, and 5.46 and 5.57 × 10−2 for scalar spontaneous strain. It was found that the spontaneous strain in each of the materials under test was very little impacted by the variation in the complexity of the A sublattice's composition. In addition, thermal expansion coefficients of both polymorphs were determined, which range from 12.7 × 10−6 K−1 to 13.2 × 10−6 K−1 for the monoclinic structure and 9.7 × 10−6 K−1 to 9.9 × 10−6 K−1 for the tetragonal one.

Continuous supercritical hydrothermal synthesis of stabilized ZrO2 nanocomposites: Doping mechanism of typical metals and transition elements

In this study, Mg, Ce, Y and La-doped nano-zirconia particles were successfully obtained by continuous supercritical hydrothermal synthesis combined with nanotechnology and crystal stabilization technology. Through detailed characterization and analysis of the structure, crystal form, grain size of the particles and by-products, the doping amount of different element dopants was optimized, and the stable pathway of tetragonal and cubic phases was proposed. Moreover, the doping mechanisms of different elements and phase diagram of doped nano-zirconia were revealed. The results show that the crystal form is determined by the doping amount, ionic radius and intrinsic properties of ions. Y and Ce doping can completely stabilize the tetragonal or cubic phase without the formation of by-products. Mg and La doping produce by-products of Mg(OH)2 and La2O2CO3. As the ionic radius increases, the radius mismatch with Zr4+ leads to a stronger ability to stabilize the tetragonal or cubic phase. At the same time, minimum dopant for stable tetragonal or cubic phases will decrease.

STRUCTURAL CHANGES IN CdTe SINGLE CRYSTALS UPON IRRADIATION WITH HEAVY IONS OF INDERENT GASES

The paper presents the results of studies on the production of a polycrystalline or amorphous layer by irradiation of single-crystalline cadmium telluride with ions of inert gases differing in radii. The influence of the ion radius on the resistivity and structure of the (111) layer of a single crystal of cadmium telluride has been studied. The samples were irradiated with neon, argon and xenon ions with radii of 38, 71 and 108 picometers (10-12 m), respectively. The radiation dose for all ions was 250 Mrad. It has been shown that ions with a large radius have the strongest influence on structural transformations; at the same dose (250 Mrad), the drop in intensity of the (111) reflection under the influence of xenon ions is twice as high as that of neon ions. In accordance with X-ray data, as the radius of the ion increases, the resistivity increases, and the larger the radius of the ion, the greater the rate of increase r. Irradiation transforms a single crystal into a polycrystalline state with the formation of a large number of defects, which are sources of current carrier capture, which leads to an increase in r. The increasing growth of r with increasing ion radius is apparently due to the fact that ions with a larger radius have a significantly larger effective cross section for interaction with the crystal.

Influence of alkali metal ions (Li+, Na+, and K+) on the redox thermodynamics and kinetics of organic electrode materials for rechargeable batteries

Organic electrode materials have been widely applied in rechargeable Li, Na, and K batteries. However, one of the key scientific issues—the influence of Li+, Na+, and K+ ions on the redox thermodynamics and kinetics is still unclear. Herein, by using n-type poly(anthraquinonyl sulfide) (PAQS) and polyimide (PI) and p-type polytriphenylamine (PTPAn) as examples, we have systematically and deeply studied this problem though elaborate electrochemical tests and theoretical calculations. By employing three-electrode cells, the thermodynamic potentials of Li, Na, K metal electrodes as well as the PAQS, PI, and PTPAn organic electrodes have been accurately measured. They follow the order of Li+ > Na+ > K+ for PAQS and PI, and keep unchanged for PTPAn. As an application of this discovery, PAQS–PTPAn dual-ion full-cells show the highest output voltage and low-temperature performance with K+ ion. To explain the tendency, universal thermodynamic models have been established and the theoretical calculations reveal that with the increase of ionic radius, the interactions of metal ion with electrolyte solvent and discharged n-type organic (N–) become weaker, which lower down the thermodynamic potential and enhance the redox kinetics. This work provides a significant guidance for the design of high-performance organic batteries.

DFT Analysis of the Electronic and Structural Properties of Lanthanide Nitride Cluster Fullerenes Ln3N@C80

We have undertaken a DFT study of the nitride cluster fullerenes (NCFs) Ln3N@C80 for the complete series of fourteen lanthanides plus lanthanum by using the PBE functional with the Grimme’s dispersion correction (PBE-D2). We tested the DN and DND basis sets, which are equivalent to 6-31G and 6-31G(d) Pople-type basis sets, respectively. Due to the known convergence problems when treating lanthanide-containing systems, only with the DN basis set was it possible to complete the calculations (geometry optimization and analysis of selected electronic parameters) for all the fifteen NCFs. We found that the bending of the Ln3N cluster increases as the ionic radius increases, in general agreement with the available X-ray diffraction data. The Ln3N cluster becomes more planar as the Ln–N bond length is contracted, and the C80 cavity slightly deforms. The HOMO-LUMO energies and distribution, as well as the charge and spin of the encapsulated metal ions, are analyzed.

Experimental determination of the enthalpy of formation of the pyrochlore rare‐earth hafnates

In this study, enthalpies of formation of compounds RE2Hf2O7 type (where RE = La, Pr, Nd, Sm, Eu, and Gd), with pyrochlore structure have been measured by high-temperature oxide melt solution calorimetry. Results were compared with literature data, and dependencies of enthalpies of the formation of compounds with the pyrochlore structure from the ionic radius of rare-earth element were analyzed. The enthalpy of formation becomes more positive with the increase in ionic radius, which is in conformity with the results earlier observed for titanates and zirconates.

Flash Sintering Preparation and Characterizations of (M0.5Ta0.5)0.05Ti0.95O2 (M = Al, Ga, In) Colossal Dielectric Ceramics

In this paper, (M0.5Ta0.5)0.05Ti0.95O2 (M = Al, Ga, In) ceramic materials were successfully prepared by Flash Sintering (FS) under an electric field of 550 V cm−1 at 1200 °C for 18 min. The influences of different ionic radius on flash sintering behavior, crystal structure, microstructure and dielectric properties of TiO2-based colossal permittivity (CP) ceramics were systematically investigated. FS can reduce the sintering temperature by 200 °C and shorten the sintering time by more than 12 times. The results show that all flash sintering samples were pure rutile TiO2 structure. The grain size decreased with increasing ionic radius. ATTO had the lowest dielectric loss of 0.2 and ITTO had a maximum dielectric constant of 8100 at 1 kHz. XPS analysis confirms that Ti3+ content increased gradually with increasing ion radius. Impedance spectroscopy analysis shows that all flash sintering ceramics were composed of semi-conductive grains and insulating grain boundaries. The CP behavior was explained using the internal barrier layer capacitance effect. This work provides a very meaningful method for the preparation of co-doped TiO2 CP ceramic materials.

The Application of Cellulose Acetate Membranes for Separation of Fermentation Broths by the Reverse Osmosis: A Feasibility Study.

Recently, there has been a special research focus on the bioconversion of glycerol to 1,3-propanediol (1,3-PD) due to its significance in the chemical industry. However, the treatment and separation of fermentation broths is a great challenge. Currently, the reverse osmosis (RO) process is a reliable state-of-the-art technique for separation of biological solutions. This study (as the first to do so) investigated the feasibility of separation of 1,3-PD broths with the use of cellulose acetate (CA) membrane by the RO process. The experiments were carried out using the installation equipped with the plate module, under the transmembrane pressure (TMP) and temperature of 1 MPa and 298 K, respectively. It was found that the used membrane was suitable for broth separation. Indeed, it was noted that 1,3-PD, as a target product, migrated through the membrane; meanwhile, other broth components were rejected in various degrees. Moreover, it was proven that retention of carboxylic acids tended to increase with increasing molecular weight, according to the following order: succinic acid > lactic acid > acetic acid > formic acid. With regards to ions, retention degree increased with the increase of ionic radius and decrease of diffusion coefficient. Finally, it was demonstrated that the CA membrane is resistant to irreversible fouling, which has a positive effect on the economic viability of the process.

The effect of ion radius on luminescence for alkali ions doping in Y2O3: Yb3+/Ho3+ thin film

In this paper, alkali ion (Li+ Na+ K+ and Rb+)-doped Y2O3:Yb3+/Ho3+ up conversion films were prepared using the sol–gel method. The structures of the films were studied by using X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. A series of high-quality thin films with good crystallization were prepared. For all samples, two emission bands were observed: green emission at 539 (550) nm and red emission at 664 nm, which can be attributed to 5F4 (5S2)→5I7 and 5F5→5I8, respectively. The green emission is dominant, and the red emission is extremely weak. The effect of each alkali-ion dopant on the emission and color adjustment of samples was investigated. The green emission intensity is increased by a factor of 6.33 (Li), 2.03 (Na), 4.82 (K) and 1.92 (Rb) with increasing alkali-ion doping concentration, and red emission is increased by a factor of 7.80 (Li), 1.92 (Na), 4.78 (K) and 1.90 (Rb). The extreme value appears earlier with increasing ion radius. Li+ doping boosts luminescence in three ways, and the other alkali ions affect the light emission in two ways. Li+ doping and K+ doping can be used to adjust the color coordinates towards the 539 nm and 550 nm directions, respectively. Na+ and Rb+ doping can enhance emission with a stable color. This means that each alkali ion is a suitable choice as a color-regulating ion and can play a role in the regulation of luminescence.

Synthesis, crystal structure of LiCaRE5(BO3)6 (RE = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) and Eu3+ luminescence in LiCaRE5(BO3)6 (RE = Gd, Y, Lu)

A series of rare earth polyborate with the general formula LiCaRE5(BO3)6 (RE ​= ​Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) were synthesized by high temperature solid state reactions. In literature, the Cd-analogues and LiCaTb5(BO3)6 were reported, here Rietveld refinements were performed on high quality powder X-ray diffraction data and the crystallographic parameters were obtained for the title compounds. Eu3+-luminescence in LiCaRE5(BO3)6 (RE ​= ​Gd, Y, Lu) were characterized. Eu3+ activators were doped into both the close-to-centrosymmetric and strongly-distorted coordination environments. Overall, bright orange-red emission can be observed with a slight increase of the red-to-orange (R/O) ratio with RE3+ ionic radius increases.

Nanometric Fluctuations of Sound Velocity in Alkali Borate Glasses and Fragility of Respective Melts

The network structure of borate glass is remarkably modified by the addition of alkali metals. The alkali metal dependences of the first sharp diffraction peak (FSDP) and the boson peak (BP) are investigated in alkali borate glasses by elastic and inelastic neutron scattering experiments. With an increase in ionic radius of alkali ions, both the width ΔQ of FSDP and the BP energy decrease. The comparison of the characteristic length of medium‐range order (MRO) predicted by the FSDP and the position of the BP allows us to find the mean‐square fluctuations of the transverse sound velocity within series of alkali borate glasses. It is shown that the fragility of the respective alkali borate melts inversely correlates with the mean‐square fluctuations of the transverse sound velocity in glassy state.

Electrical and electrochemical properties of the Sr(Fe,Co,Mo)O3−δ system as air electrode for reversible solid oxide cells

The effects of Co and Mo doping on the properties of SrFeO3-δ perovskite as air electrode in reversible solid oxide cells have been analysed. The oxygen-ordered parent phase exhibits a high oxygen-vacancy content, which is partially reduced on doping, accompanied by stabilisation of cubic symmetry for SrFe0.9Mo0.1O3-δ and SrFe0.45Co0.45Mo0.1O3-δ phases. All compositions lose oxygen for temperatures ≥400–450 °C, with a concomitant decrease of electron-hole conductivity. Oxide-ionic conductivity determined by Faradic efficiency significantly improves for the Co-doped composition, reaching 0.026 S cm−1 at 750 °C. The increase of ionic radii with reduction of Fe/Co + IV species results in greater thermal expansion for T > 450 °C. Polarization resistance without bias lowers considerably on Co doping, from ~0.55 Ω cm2 for pure SrFeO3-δ, to ~0.2 Ω cm2 for SrFe0.45Co0.45Mo0.1O3-δ at 700 °C, but not on Mo doping (~0.5 Ω cm2). However, under cathodic and anodic polarization, a comparable, excellent performance at 650 °C of all compositions indicates their considerable promise as air electrodes for reversible solid oxide fuel cell-electrolyser systems, particularly for SrFe0.9Mo0.1O3-δ with more moderate thermal expansion.

Sandwich double-decker Er(iii) and Yb(iii) complexes containing naphthalocyanine moiety: synthesis and investigation of the effect of a paramagnetic metal center.

Novel heteroleptic Er(iii) and Yb(iii) naphthalocyaninato-phthalocyaninates containing an octa-phenyl or octa-phenoxysubstituted naphthalocyanine deck were synthesised and identified by 1H NMR, EPR and high resolution MALDI-TOF/TOF mass spectrometry. Direct synthesis of novel homoleptic Yb(iii) bis (octa-phenylnaphthalocyaninate) was carried out. Downfield lanthanide induced shifts of the aromatic protons in target compounds were observed compared with the corresponding diamagnetic Lu(iii) complexes. In the near-IR absorption spectra, an increase in ionic radius from Lu(iii) to Er(iii) resulted in a bathochromic shift of the intervalence band up to 1473 nm. This work presents the first experimental EPR study of Yb(iii) bis naphthalocyaninate, where a set of magnetic parameters and properties (including spin, magnitude and sign of magnetic anisotropy parameter D, increased splitting in a crystal field, ferromagnetic f-π interaction etc.) were determined and interpreted by both EPR and SQUID techniques and supported by theoretical considerations.

Insights into the effect of the interlayer spacings of bilayer graphene on the desolvation of H+, Li+, Na+, and K+ ions with water as a solvent: a first-principles study.

The desolvation effect of ions plays an important role in adjusting the capacity of supercapacitors and has attracted considerable attention after its discovery. Here, first-principles calculations were conducted to calculate the reaction energies of ions, water, and hydrated ions in bilayer graphene (BG) with different interlayer spacings (d) and to explore the desolvation behaviors of H+, Li+, Na+, and K+ ions. The calculated results showed that H+ can only exist in the state of H3O+ in AA-stacking BG, and desolvation exists only in the case of AB-stacking BG. The complete desolvation size for H+ ions in the AB-stacking system reached 5.6 Å, which was the largest desolvation size of the four ions studied. The critical desolvation sizes of Li+, Na+, and K+ in the BG layers of AA- and AB-stacking increased sharply as a consequence of the increasing ionic radius. However, the complete desolvation sizes of all three ions were in the range of 4-5 Å and with the increase in ionic radius, the complete desolvation sizes showed a reverse tendency. The complete desolvation size of Na+ in AB-stacking BG was slightly larger than that in AA-stacking BG. Further analysis presented that the ionic radii of H+, Li+, Na+, and K+ ions make a dominant contribution to the critical size of desolvation. Our present results provide useful information for improving the capacity of supercapacitors by precisely matching the pore structure and electrolyte through the adjustment of the pore structure of carbon materials.

Thermodynamics and Stability of Rhabdophanes, Hydrated Rare Earth Phosphates REPO4 · n H2O.

Rare earth phosphates comprise a large family of compounds proposed as possible nuclear waste disposal forms. We report structural and thermodynamic properties of a series of rare earth rhabdophanes and monazites. The water content of the rhabdophanes, including both adsorbed and structural water, decreases linearly with increase in ionic radius of the rare earth. The energetics of the transformation of rhabdophane to monazite plus water and the enthalpy of formation of rhabdophane from the constituent oxides was determined by high temperature drop solution calorimetry. The former varies linearly with the ionic radius of the lanthanide, except for cerium. By combining the enthalpy of formation determined by high temperature drop solution calorimetry and the free energy of formation determined previously by solubility experiments, a complete set of thermodynamic data was derived for the rhabdophanes. They are thermodynamically metastable with respect to the corresponding monazites plus water at all temperatures under ambient pressure conditions. This conclusion strengthens the case for monazites being an excellent nuclear waste form.

Engineering Proton Transfer in Photosynthetic Oxygen Evolution: Chloride, Nitrate, and Trehalose Reorganize a Hydrogen-Bonding Network.

Photosystem II oxidizes water at a Mn4CaO5 cluster. Oxygen evolution is accompanied by proton release through a 35 Å hydrogen-bonding network to the lumen. The mechanism of this proton-transfer reaction is not known, but the reaction is dependent on chloride. Here, vibrational spectroscopy defines the functional properties of the proton-transfer network using chloride, bromide, and nitrate as perturbative agents. As assessed by peptide C═O frequencies, bromide substitution yields a spectral Stark shift because of its increase in ionic radius. Nitrate substitution leads to more complex spectral changes, consistent with an overall increase in hydrogen-bonding interactions with the peptide backbone. The effects are similar to spectral changes previously documented in site-directed mutations in a putative lumenal pathway. Importantly, the effects of nitrate are reversed by the osmolyte, trehalose. Trehalose is known to alter hydrogen-bonding interactions in proteins. Trehalose addition also reverses a shift in an internal hydronium ion signal, consistent with an alteration in its p Ka value and a change in the basicity of bound nitrate. The spectra provide evidence that the proton-transfer pathway contains peptide carbonyl groups, internal water, a hydronium ion, and amino acid side chains. These experiments also show that the proton-transfer pathway functionally adapts to changes in electric field, p Ka, and hydrogen bonding and thereby optimizes proton transfer to the lumen.