Interionic Distance Research Articles

Could λ-Ti3O5 with lamellar and channel microstructure characteristics determine the excellent properties of LIBs? The first-principles study of λ-Ti3O5 lithiation mechanism

While people are searching for potential electrode materials for Li-ion batteries (LIBs), it is controversial whether the microstructure is a critical factor of electrochemistry property. λ-Ti3O5 is an example due to its lamellar and channel microstructure characteristics to discuss whether the microstructure characteristic is the critical factor of properties of LIBs. The intercalation/de-intercalation mechanisms and diffusion behavior of Li-ion in λ-Ti3O5 are studied by DFT. The binding energies with the different number of Li-ions are from − 3.1 to − 2.2 eV, and the volume changes are from 0.1% to 1.3%, indicating λ-Ti3O5 is stable during lithiation. The supercell and (001) slab of λ-Ti3O5 is constructed to investigate the diffusion behaviors of Li-ion in bulk and Li-ion escaping from the system, respectively. The former energy barriers are about 1.0 eV, and the latter energy barriers are above 2.0 eV, suggesting it is difficult for Li-ion to diffuse in or escape from the system. It presumably can be inferred that the microstructure is not the critical factor of diffusion property for electrode materials. More studies are needed to optimize the performance of λ-Ti3O5 as an electrode material, such as interionic distance and strength of bonding.

Fast estimation of ion-pairing for screening electrolytes: A cluster can approximate a bulk liquid.

The propensity for ion-pairing can often dictate the thermodynamic and kinetic properties of electrolyte solutions. Fast and accurate estimates of ion-pairing can thus be extremely valuable for supplementing design and screening efforts for novel electrolytes. We introduce an efficient cluster model to estimate the local ion-pair potential-of-mean-force between ionic solutes in electrolytes. The model incorporates an ion-pair and a few layers of explicit solvent in a gas-phase cluster and leverages an enhanced sampling approach to achieve high efficiency and accuracy. We employ harmonic restraints to prevent solvent escape from the cluster and restrict sampling of large inter-ion distances. We develop a cluster ion-pair sampling tool that implements our cluster model and demonstrate its potential utility for screening simple and poly-electrolyte systems.

Study of the influence of MoO3 concentration on the chemical structure, physical properties, and radiation absorption prowess of alumino lead borate glasses

The present study presents the preparation of a glass system with composition of 55B2O3 - 30Pb3O4- Al2O3- MoO3, where by melt quenching conventional method. The structure of the synthesized samples was examined by XRD and FT-IR techniques. It was found that the molybdenum acts as a modifier and enhances the change between BO3 and BO4 structural units. Increasing MoO3 in the sample improved the glass network compactness. The influence of MoO3 content was studied on several physical parameters such as inter-ionic distance (Ri), the polaron radius (rp) and internuclear distance (ri), B—B separation (dB-B) average coordination number, number of bonds, field strength of (Mo+3), and the floppy modes. Increasing MoO3 doping concentration from 0–5 mol % produced corresponding increase in fast neutron effective removal cross section from 0.07127–0.10825 cm−1, total cross section for thermal neutrons from 68.35875–105.7526 cm−1, and an increment in the cold neutron scattering cross section. Furthermore, the influence of MoO3 doping in the glasses was such that the stopping powers and ranges RCSDA /Rp of electrons, proton, alpha particles, and carbon ion follows the trend: BPAM-G1 > BPAM-G2 > BPAM-G3 > BPAM-G4 > BPAM-G5, and (RCSDA /Rp)BPAM-G1 > (RCSDA /Rp)BPAM-G2 > (RCSDA /Rp)BPAM-G3 > (RCSDA /Rp)BPAM-G4 > ((RCSDA /Rp)BPAM-G5 respectively. On the other hand, the doping produced no noticeable differences in the equivalent atomic number and the exposure buildup factor of the glasses.

Energy landscapes and dynamics of ion translocation through membrane transporters: a meeting ground for physics, chemistry, and biology.

The dynamics of ion translocation through membrane transporters is visualized from a comprehensive point of view by a Gibbs energy landscape approach. The ΔG calculations have been performed with the Kirkwood-Tanford-Warshel (KTW) electrostatic theory that properly takes into account the self-energies of the ions. The Gibbs energy landscapes for translocation of a single charge and an ion pair are calculated, compared, and contrasted as a function of the order parameter, and the characteristics of the frustrated system with bistability for the ion pair are described and quantified in considerable detail. These calculations have been compared with experimental data on the ΔG of ion pairs in proteins. It is shown that, under suitable conditions, the adverse Gibbs energy barrier can be almost completely compensated by the sum of the electrostatic energy of the charge-charge interactions and the solvation energy of the ion pair. The maxima in ΔGKTW with interionic distance in the bound H+ -A- charge pair on the enzyme is interpreted in thermodynamic and molecular mechanistic terms, and biological implications for molecular mechanisms of ATP synthesis are discussed. The timescale at which the order parameter moves between two stable states has been estimated by solving the dynamical equations of motion, and a wealth of novel insights into energy transduction during ATP synthesis by the membrane-bound FOF1-ATP synthase transporter is offered. In summary, a unifying analytical framework that integrates physics, chemistry, and biology has been developed for ion translocation by membrane transporters for the first time by means of a Gibbs energy landscape approach.

Influence of Cu2+ substitution on structural and optical properties of Mg-Zn ferrite nanoparticles

The Cu2+ doped CuxMg0.5Zn0.5-xFe2O4 [x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5] ferrite nanoparticles were synthesized by co-precipitation method using oxalate precipitant. The synthesized oxalate precursors have been characterized by Elemental analysis, FT-IR and Thermogravimetry. The structural and optical properties of final ferrite samples have been investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FT-IR) and UV–Vis Diffuse Reflectance Spectroscopy. The XRD patterns reveals no additional peaks due to second phase i.e. single phase cubic Cu-Mg-Zn ferrites nanoparticles are formed. The parameters like theoretical and experimental lattice constant, crystallite size, X-ray density and unit cell volume extracted from XRD data. It is noticed that with increasing Cu2+ doping lattice parameter and unit cell volume are decreased while X-ray densities are increased. The interionic distances like ionic radii, bond lengths, hopping lengths and anion-anion distance were also evaluated. FT-IR spectra exhibit two distinct absorption bands in the range of 568–589 cm−1 and 448–461 cm−1 which are characteristic of ferrite. Different force constants and Debye temperature for synthesized samples found in agreement with literature. The absorption spectra and Energy band gaps are evaluated by using UV–Vis DRS. The energy band gaps Cu-Mg-Zn ferrites found in the range of 1.643 eV–1.557 eV. UV–Vis DRS analysis showed that the band gap energy decreases with increasing Cu2+ doping.

Structure and cationic distribution dependent soft magnetic properties of single-domain Mg1−xNixFe2O4 (0 ≤ x ≤ 1.0) nanocrystals

The effects of Ni2+ doping on the crystalline lattice and corresponding magnetic properties of Mg1−xNixFe2O4 nanocrystals, synthesized by a microwave combustion, are systematically studied. Highly crystalline nanoparticles with average size of 20–30 nm and stoichiometric chemical compositions are indicated by results of transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The structural properties including lattice parameter, cationic radii, cationic distribution, bond lengths and angles have been estimated based on Rietveld analysis of the x-ray diffraction (XRD) patterns. Mostly inverse spinel structure in MgFe2O4 with an observed nonmonotonic increase of the inversion factor by Ni substitution and almost complete inversion for × ≳ 0.5 indicate competitive site preferences of the cations. The synthesized nanocrystals exhibit soft single-domain magnetic properties within a critical domain size of about 30–40 nm and magnetic moment that is well theoretically generated based on the cationic distribution, consistently estimated from the XRD and Mössbauer spectroscopy analyses. A monotonic increase in the magnetization and drastic decrease in coercivity by Ni substitution result in low anisotropy constant of about 5500 erg/g for the mostly soft ferromagnet Mg0.5Ni0.5Fe2O4. We discuss the evolution of the magnetic properties in a correlation with the cationic re-distribution and corresponding structural changes in the interionic distances and angles by Ni doping.

Synthesis of Pb3O4-SiO2-ZnO-WO3 Glasses and their Fundamental Properties for Gamma Shielding Applications

Zinc lead silicate glass system contains different amount of WO3 were fabricated using the classical melt-quench technique. The nature of the samples was investigated using X-ray diffraction. The ultrasonic velocities and elastic moduli were tested experimentally after that the results were compared by using the theoretical consideration. With increasing the WO3 content, decreasing the molar volume causes a decrease in the inter-ionic distance Ri. The FLUKA code were used to estimate the main attenuation considerations mass attenuation coefficients (MAC) and linear attenuation coefficients (LAC). The LAC increment from 0.728 cm-1 to 0.856 cm−1 as the WO3 concentration increment from 0 to 5 mol%, resulting in high shielding performance for G5. The dose rate at energy of 0.6 MeV with the G5 sample found to be declines from 2.35 × 107 R/h at 1 mm to 4.71 × 106 R/h at 4 mm. The values of mean free path (MFP) and the half value layer (HVL) are smaller than those of the traditional photon shields signifying that the fabricated samples (particularly G5) have interesting shielding characteristics to be used in applications involving x/gamma rays.

Molecular-Field Approximation in the Theory of Ferromagnetic Phase Transition in Diluted Magnetic Semiconductors

In this pedagogical paper, the comparative analysis of two common approaches describing the ferromagnetic phase transition in diluted magnetic semiconductors (DMS) is expounded in terms of the Weiss field approximation. Assuming a finite spin polarization of the magnetic ions, the treatment of carrier-ion exchange interaction in the first order evokes a homogeneous Weiss molecular field that polarizes the spins of free carriers. In turn, this spin polarization of the free carriers exerts the effective field that may stabilize the DMS spin polarization belowa critical temperature TC. The treatment of such self-consistent spontaneous DMS magnetization can be done in terms of the spin-spin interaction independent of the inter-ion distance and the infinitesimal in thermodynamic limit. On the other hand, by additionally accounting for the second-order effects of the carrier-ion exchange interaction, we can treat a Weiss field in terms of the Ruderman–Kittel–Kasuya–Yosida indirect spin-spin interaction, which oscillates and does not disappear at finite inter-ion distances in the case of a finite concentration of carriers. These both approaches result in the same Curie temperature TC provided a non-correlated homogeneous random distribution of the localized spin moments over the sample volume. We discuss the origin of such coincidence and show when this is not a case in other more realistic models of the conducting DMSs.

Efficient white upconversion luminescence in Yb3+/Eu3+ doubly-doped transparent glass ceramic.

Efficient white upconversion (UC) luminescence is obtained in Yb3+/Eu3+ doubly-doped optical glass ceramic (GC) for the first time. KYb3F10 nanocrystals are controllably precipitated from the amorphous networks via the inducing of Yb3+. Yb3+ ions are spontaneously confined within the compact fluoride crystal structures to produce efficient blue UC emissions of Yb3+-Yb3+ pairs. Eu3+ ions are easily incorporated into the KYb3F10 crystal lattices. Owing to the extremely short interionic distance in the crystal structures, intense green UC emissions apart from the red emissions of Eu3+ are observed, which are not obtained by the traditional Yb3+/Eu3+ doubly-doped GCs. As a result, white UC emissions are synthesized based on the three-primary-color principle and the emission intensities of GCs are dramatically enhanced as compared to glass. The designed GCs provide novel optical gain materials for the promising applications in three-dimensional display, solid-state lighting and tunable fiber lasers.

Physical, optical, structural and thermoluminescence behaviour of borosilicate glasses doped with trivalent neodymium ions

Trivalent neodymium ion (Nd 3+ ) activated sodium magnesium borosilicate glasses having composition (60 – x) B 2 O 3 –20SiO 2 – 10 Na 2 O – 10 MgO – x Nd 2 O 3 (where x = 0, 0.04, 0.08, 0.12, 0.16, 0.2 mol%) were synthesized by melt quenching method to study the structural, physical, optical and thermoluminescence behaviour. The physical parameters like molar volume, density, molecular weight, average boron-boron separation, field strength, ion concentration, polaron radius, interionic distance, oxygen packing density and optical basicity were obtained. The structural information was acquired through Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD spectra suggested the amorphous nature of present media and FTIR spectra highlighted the bands present in this amorphous media. To study the optical parameters such as direct band gap, indirect band gap, refractive index, optical dielectric constant, reflection loss, dielectric constant, molar refractivity, molar polarizability, metallization, electronic polarizability, oxide ion polarizability, transmission coefficient, energy band gap based metallization criterion, refractive index based metallization criterion, non-linear optical susceptibility, non-linear refractive index and Urbach model, optical absorption spectra was recorded in the range of 190–1100 nm. These glasses were irradiated with gamma rays to study the thermoluminescence glow curve at six different doses such as 50 Gy, 100 Gy, 500 Gy, 1 kGy, 5 kGy and 10 kGy. The trapping or kinetic parameters like frequency factor, activation energy and kinetic order were also studied by using peak shape method. Linear dose response curve indicates that the 59.92 B 2 O 3 – 20 SiO 2 – 10 Na 2 O – 10 MgO – 0.08 Nd 2 O 3 sample can be considered as a potential candidate for radiation dosimetry. • Fabrication of Trivalent neodymium ion (Nd 3+ ) activated sodium magnesium borosilicate glasses. • The density increases from 1.616 to 2.079 (gcm −3 ) with increase in Nd 2 O 3 concentration from 0 to 0.2 mol%. • The direct and indirect band gap energy values decrease from 3.408 to 3.253 eV and 1.537–1.446 eV respectively with increase in content of Nd 2 O 3 . • 59.92 B 2 O 3 – 20 SiO 2 – 10 Na 2 O – 10 MgO – 0.08 Nd 2 O 3 sample can be considered as a potential candidate for radiation dosimetry.

Fabrication and characterization of barium based bioactive glasses in terms of physical, structural, mechanical and radiation shielding properties

A novel bioactive glass system 20SiO2- 7.5Na2O- 7.5K2O- (65-x)P2O5- xBaO (where x = 2.5, 5.0, 7.5 and 10.0 mol %) has been fabricated using melt quenching method and corresponding samples named as GB1, GB2, GB3 and GB4, respectively. The formation of glass has been confirmed by X-ray diffraction (XRD) analysis. Physical and structural properties include measurement of density (ρGlass), molar volume (Vm), oxygen packing density (OPD), oxygen molar volume (Vmo), ionic concentration measurement (N), interionic distance (R), Polaron radius (Rp) and Phosphorous molar volume Vmpfor all the selected glass samples. Mechanical properties include packing density (Vt), Young's modulus (Y), bulk modulus (K), shear modulus (S), longitudinal modulus (L), hardness (H) and Poisson's ratio (σ) has been studied using Makishima-Mackenzie and Rocherulle models. Radiation shielding properties viz. mass attenuation coefficient (MAC), effective atomic number (EAN), effective electron number (EEN), half value layer (HVL) and tenth value layer (TVL) have been evaluated theoretically using the WinXCom and PSD software packages for all the glass samples and experimentally verified at selected photon energies of 511 keV (Na22), 662 keV (Cs137), 1173 keV and 1332 keV (Co60) using gamma ray spectroscopy. Additionally, some of these radiation shielding properties for the fabricated glasses were compared with commercially used concretes, radiation shielding glass (RS253 G-18) and registered 45S5 Bioglass®. GB4 glass sample is found to possess all the qualities which are essential for an ideal radiation shielding material and can easily replace commercially used radiation shielding materials.

Research on the Effects of Yttrium on Bismuth Titanate Borosilicate Glass System

Glasses with the chemical composition of 52B2O3 – 12SiO2–26Bi2O3 – (10 − x)TiO2 - xY2O3, :(0 ≤ x ≤ 10) prepared using the melt-quench method. The goal of this study is to investigate the structural, mechanical, and radiation shielding characteristics of these samples. XRD analysis has explored the nature of the glass system. Molar volume obtained reduced while the density denotes increased in the present system. As the molar volume decrease inter-ionic distance, polaron radius, inter-nuclear distance, and Y-Y separation of the investigated glasses decreased. The mechanical characteristics depend on the glass structure of the current glasses sample. Ultrasonic velocities and elastic moduli (experimental and theoretical) for these glasses obtained they were observed to get enhanced. The radiation shielding efficiency was investigated by Phy-X/PSD software. The mass attenuation coefficient, mean free path, half-value layer, tenth value layer, and effective atomic number of glasses have been designed to simulate gamma photon energies between 0.015 and 15 MeV.

Structural, optical, thermal and other physical properties of Bi2O3 modified Lithium Zinc Silicate glasses

A series of 60SiO2–15ZnO-(25-x)Li2O-xBi2O3 glasses with x = 0, 5, 10, 15 and 20 mol% were synthesized using conventional melt-quenching method and their amorphous nature was ascertained by X-ray diffraction technique. The variation in physical parameters viz. density (ρ), crystalline volume (Vc), molar volume (Vm) and oxygen packing density (OPD) with composition of as- prepared glass samples has been analyzed. The physical properties related parameters such as average value of silicon- silicon (Si-Si) separation 〈dSi-Si〉, polaron radius (Rp), Bi3+ ion concentration (N), bismuth yield field strength (F) and interionic distance (Ri) have been determined. Investigations of infrared and Raman spectra reveal that tetrahedral [ZnO4] and [SiO4] structural units are main building blocks of glass network, whereas, Bi2O3 exists as both network modifier octahedral [BiO6] and network former pyramidal [BiO3] structural units. Optical bandgap energy (Eg) values determined by UV–VIS-IR spectroscopy indicate a decreasing trend with increasing Bi2O3%. The as-prepared glasses possess relatively high values of the optical basicity (1.069–1.208), electronic oxide ion polarizability (4.522–7.893 Å3), third order non-linear optical susceptibility (0.086–0.922 × 10−11esu) and metallization criterion (0.2991–0.4396) thereby implying that the present glasses may be suitable in non-linear optical applications.

Structural and Photoluminescence Investigations of Tb3+/Eu3+ Co-Doped Silicate Sol-Gel Glass-Ceramics Containing CaF2 Nanocrystals.

In this work, the series of Tb3+/Eu3+ co-doped xerogels and derivative glass-ceramics containing CaF2 nanocrystals were prepared and characterized. The in situ formation of fluoride crystals was verified by an X-ray diffraction technique (XRD) and transmission electron microscopy (TEM). The studies of the Tb3+/Eu3+ energy transfer (ET) process were performed based on excitation and emission spectra along with luminescence decay analysis. According to emission spectra recorded under near-ultraviolet (NUV) excitation (351 nm, 7F6 → 5L9 transition of Tb3+), the mutual coexistence of the 5D4 → 7FJ (J = 6–3) (Tb3+) and the 5D0 → 7FJ (J = 0–4) (Eu3+) luminescence bands was clearly observed. The co-doping also resulted in gradual shortening of a lifetime from the 5D4 state of Tb3+ ions, and the ET efficiencies were varied from ηET = 11.9% (Tb3+:Eu3+ = 1:0.5) to ηET = 22.9% (Tb3+:Eu3+ = 1:2) for xerogels, and from ηET = 25.7% (Tb3+:Eu3+ = 1:0.5) up to ηET = 67.4% (Tb3+:Eu3+ = 1:2) for glass-ceramics. Performed decay analysis from the 5D0 (Eu3+) and the 5D4 (Tb3+) state revealed a correlation with the change in Tb3+–Eu3+ and Eu3+–Eu3+ interionic distances resulting from both the variable Tb3+:Eu3+ molar ratio and their partial segregation in CaF2 nanophase.

Racah Parameter and Nephelauxetic Effect on Er<sup>3+</sup>/Nd<sup>3+</sup> Codoped Lithium Niobate Tellurite Glass

The modification of absorption characteristics in rare-earth doped tellurite glasses is important in photonics application. The Er3+/Nd3+ doped glasses of the form (69-x)TeO2-15Li2CO3-15Nb2O5-1Er2O3-(x)Nd2O3 with x= 0.4, 0.8 and 1.0 mol % are successfully made by using conventional melt-quenching technique. Physical properties such as polaron radius, interionic distance, field strength and average distance between acceptors and donors are determined. The absorption spectra reveal eleven prominent peaks centered at 6535.9 cm-1, 10245.9 cm-1, 11415.5 cm-1, 12437.8 cm-1, 13369.0 cm-1, 15267.2 cm-1, 15949.2 cm-1, 17127.1 cm-1, 19084.0 cm-1, 20449.9 cm-1 and 22271.7 cm-1 which corresponding to the transitions from ground state to various states of Nd3+ ions. The crystal field site increases from 8.120 to 8.169 cm-1 due to increase in contraction of Nd3+-ligand. The nephelauxetic function, increase 0.104 to 0.107. The increasing in value describes, the increasing in ionic bond from-0.0004 to-0.0011. The increment in exhibits the increase in the number of effective positive charge connected to neodymium atom and attracts the electrons from ligands as it increases from 1.0004 to 1.0011. These present glass shows the potential candidate of broadband amplifiers and lasers as it is comparable with other Nd3+ doped another host.

COMPARATIVE CRYSTAL FIELD ANALYSIS OF THE NI2+ ENERGY LEVEL SCHEME IN CdCl2, CdBr2, CdI2 CRYSTALS

The exchange charge model of crystal field was used to calculate the crystal field splitting of all Ni2+ energy levels (3d8 electron configuration) in three structurally similar crystals of CdCl2, CdBr2, and CdI2. The influence of the nature of the ligands and interionic distances on the values of the crystal field parameters and location of the split energy levels and relative intervals between them was identified. Comparison of the calculated energy levels with the experimental results available in the literature yielded good agreement.

Spectral investigations of dysprosium (Dy3+) ions doped ZnBiNaPSr oxyfluoride glasses for intense white light emitting diodes (w-LEDs)

Oxyfluoride (P2O5 + Bi2O3 + Na2CO3 + SrCO3 + ZnF2) glasses doped with different dysprosium (Dy3+) ion concentrations (0.5, 1.0, 1.5 & 2 mol %) have been synthesized using conventional melt quenching technique. The Physical and optical parameters such as density (ρ), refractive index (n), polaron radius (rp), interionic distance (ri), field strength (F), electron polarizability (αe), molar refractivity (RM), reflection loss (R), etc., were evaluated. The X-ray diffractograms were recorded in the 10–900 region, showed amorphous nature. Surface morphological studies were performed with SEM and elemental analysis has also been performed with EDS. The absorption spectra consist of a few well-defined high intense bands in the UV–Vis-NIR region. The optical band gaps were estimated from the tauc’s plots drawn from the absorption spectra and obtained values exhibited nonlinear behaviour with dopant ion concentration. The emission spectra were recorded by monitoring the excitation wavelength at 453 nm which consists of three emission bands at 487, 557 and 667 nm, due to f-f characteristic transitions of Dy3+ ion. The Judd-Ofelt and radiative parameters have been calculated from absorption and luminescence spectra. It has been noticed that the concentration quenching effect was observed for higher concentrations (1.5 and 2.0 mol %) in the present glass series. The emission intensity ratio between yellow and blue color bands and CIE color coordinates were evaluated. The correlated color temperature (CCT) and color purity (CP) has been evaluated using CIE 1931 chromaticity diagram. The ZnBiNaPSr: Dy1.0 glass exhibits superior luminescent properties than other concentrations and it was found to be the most prominent device for white light applications.

Hydration, Ion Distribution, and Ionic Network Formation in Sulfonated Poly(arylene ether sulfones)

We use molecular dynamics simulations to probe hydration, ion spacing, and cation-anion interaction in two sulfonated polysulfones with different ion distributions along the polymer backbone. At room temperature, these polymers remain in a glassy state even with water contents more than 10%. At the equilibrium water uptake, the ions exhibit a similar level of hydration as they would in their saturated aqueous solution. The framework of Manning's limiting law for counterion condensation is used to examine ionic interactions in the simulated polysulfones. The dielectric constant that the ions experience can be well approximated by a volume-weighted average of the dielectric constants of the polymer backbone and water. Our results show that a reasonable estimate of the average inter-ion distance, b, is obtained by using the distance where the sulfonate-sulfonate coordination number reaches 1. The spacing of the sulfonate ions along the polysulfone backbone plays a role in determining their spatial distribution inside the hydrated polymer. As a result, the value of b is slightly larger for polymers where the sulfonate ions are more evenly spaced along the backbone, which is consistent with experimental evidence. The simulations reveal that the sulfonate ions and sodium counterions form fibrillar aggregates at water contents below the equilibrium water uptake. Such extensive ionic aggregates are expected to facilitate ion transport in sulfonated polysulfone membranes, without the need for long-range chain motion as in the case of traditional rubbery ionic polymers. Our estimates for the dielectric constant and b are used in conjunction with Manning's theory to estimate the fraction of counterions condensed to the fixed ions. The prediction of Manning's theory agrees well with the simulation result.

Optical properties of bismuth tellurite glasses doped with holmium oxide

The study of polarizability, optical basicity, and electric susceptibility carried out on the new and very rare set of bismuth - tellurite glasses doped with Ho3+ ions were fabricated by the conventional melt quenching process. The non-crystalline nature was confirmed by X-ray diffractometer measurements. Physical properties such as rare earth ion concentration, interionic distance, polaron radius, and average tellurium - tellurium separation were investigated by appropriate formulae. By UV absorption spectra, optical properties of Ho3+ ions doped glasses were found in the wavelength limit from 400 to 700 nm. The optical properties like optical dielectric constant, electronic polarizability, metallization criterion, electronegativity, optical basicity, and electric susceptibility were measured with appropriate mathematical relations. The impact of Ho3+ ions on nonlinearity in optical parameters discloses bismuth tellurite glass as a new applicant for holmium doped fiber amplifier applications.

Physical, Radiation Shielding and Crystallization Properties of Na2O-Bi2O3- MoO3-B2O3- SiO2-Fe2O3 Glasses

The melt-quenching method has been used to fabricate 9Na2O-(30-x) Bi2O3- xMoO3-40B2O3- 20SiO2-1Fe2O3 glass system where x = (0 ≤ x ≤ 15 mol%). The XRD diffractometer procedure was used to check the status of these samples. Inter-ionic distance (Ri) between Mo–Mo, Polaron radius rp, and inter-nuclear distance ri reduce with the Mo content due to reduce of molar volume. The two-photon absorption coefficient TPA increase with the increase of MoO3 this increased connected to Eg. The values of ionicity Ib slightly increase and the covalency of these glasses reduce with a growth in MoO3 content. The XRD patterns of glass-ceramic show (Na2B4O7), B2Si2O5, Na2SiO3, Fe7BSi3O18, and LiBi (MoO4)2. The morphological of the glass-ceramic has been studied by SEM. FT-IR spectroscopic investigations of the glass-ceramic samples were applied to check the characteristic structure. Mass attenuation coefficient of the prepared samples decreased with the energy increase and with the addition of MoO3.