Thallium Atoms Research Articles

T-cut slotted quartz tube-atom trap strategy for the on-line preconcentration of thallium in well water samples

In this study, an on-line preconcentration system was developed for the quantitative determination of thallium in well water samples using hydrogen-assisted T-cut slotted quartz tube atom trapping (HA-T-SQT-AT) coupled to flame atomic absorption spectrometry (FAAS). The method is based on trapping the thallium atoms on the inner surface of the T-SQT for a short period using sample aspiration and lean flame conditions. Then, hydrogen gas as a reducing agent was released instantly to free the trapped analyte atoms, resulting in a sharp and narrow signal. The system analytical performance was enhanced by performing comprehensive optimization of several factors. The linear range and LOD/LOQ values of the optimized method were found to be 7.5–––200 ng/mL and 2.6/8.7 ng/mL, respectively. Accuracy/practicability of the presented method were verified using well water samples, and the percent recoveries calculated using the external calibration approach were all above 80%.

Doping of two thallium atoms in silicene nanoribbons in the electric field

Abstract The low-dimensional material that revolutionizes technology, silicene is a monolayer of silicon molecules, which is a potential material. Silicene nanoribbons (SNRs) are one-system silicene ribbons with two hydrogen-modified edges. Two thallium atoms will be doped in each unit cell of the SNRs, the electric field acting on the doped system has a magnitude of 0.1V/angstrom. The configurations studied here all exhibit stability because of the bonds between atoms. The configurations studied here all exhibit stability because of the bonds between atoms. Density functional theory (DFT) and VASP software are used to study and simulate materials.

Точечные дефекты висмута в кристаллах TlInTe-=SUB=-2-=/SUB=-, электрофизические и диэлектрические свойства твердых растворов

In this work, to determine the solubility of bismuth in TlInTe2 crystals by the methods of physicochemical analysis, we studied the phase diagram of TlInTe2 - Bi in the concentration range of 0-10 at.% Bi and studied the electrical and dielectric properties of (TlInTe2)1-x Bix solid solutions. Analyzing the obtained experimental data, we assume that bismuth atoms, penetrating into the TlInTe2 lattice, form interstitial solid solutions, occupying octahedral voids between thallium atoms in the crystallographic direction 001 (z = 0.5). The influence of bismuth impurities on the dielectric properties of TlInTe2 crystals is also observed, while forming barriers to the movement of thallium ions, bismuth impurities increase the temperature of the phase transition to the ion-conductive phase (Ti): in the crystallographic direction 001-69 K, and in the direction 110-87 K.

Study of doping a thallium atom in silicene nanoribbons in an electrical field

Silicene is a two-dimensional material made up of silicon atoms, the silicene nanoribbons (SNRs) studied here are made of silicene with edges modified by hydrogen atoms. The work doped a thallium atom into the unit cell of SNRs, the electric field acting on the system has a constant magnitude: 0.15V/Å. There are two doped structures studied, top structure and valley structure. Density functional theory (DFT) is used in this study, the bands of energy and states of the configurations will be plotted, investigated, and analysed. The partial states (s, p) will be studied.

Relativistic B-Spline R-Matrix Calculations for Electron Scattering from Thallium Atoms

The Dirac B-spline R-matrix (DBSR) method is employed to treat low-energy electron collisions with thallium atoms. Special emphasis is placed on spin polarization phenomena that are investigated through calculations of the differential cross-section and the spin asymmetry function. Overall, good agreement between the present calculations and the available experimental measurements is found. The contributions of electron exchange to the spin asymmetry cannot be ignored at low impact energies, while the spin–orbit interaction plays an increasingly significant role as the impact energy rises.

Effect of nuclear magnetization distribution within the Woods-Saxon model: Hyperfine splitting in neutral Tl

Three models of the nuclear magnetization distribution are applied to predict the hyperfine structure of the hydrogenlike heavy ions and neutral thallium atoms: the uniformly magnetized ball model and single-particle models for the valence nucleon with the uniform distribution and the distribution determined by the Woods-Saxon potential. Results for the hydrogenlike ions are in excellent agreement with previous studies. The application of the Woods-Saxon model is now extended to the neutral systems with the explicit treatment of the electron correlation effects within the relativistic coupled cluster theory using the Dirac-Coulomb Hamiltonian. We estimate the uncertainty for the ratio of magnetic anomalies and numerically confirm its near nuclear-model independence. The ratio is used as a theoretical input to predict the nuclear magnetic moments of short-lived thallium isotopes. We also show that the differential magnetic anomalies are strongly model dependent. The accuracy of the single-particle models significantly surpasses the accuracy of the simplest uniformly magnetized ball model for the prediction of this quantity. Skripnikov [Skripnikov, J. Chem. Phys. 153, 114114 (2020)] has shown that the Bohr-Weisskopf contribution to the magnetic dipole hyperfine structure constant for an atom or a molecule induced by a heavy nucleus can be factorized into the electronic part and the universal nuclear magnetization dependent part. We numerically confirm this factorization for the Woods-Saxon single-particle model with an uncertainty less than 1%.

Features of IR reflection spectra of β-Tl1-xCuxInS2 single crystals (0 ≤ X ≤ 0.015)

The method of long-wave spectroscopy made it possible to study the IR reflection spectra of layered single crystals β-Tl1-xCuxInS2 (0≤X≤0.015) in in the frequency range of 40-500 cm−1 and the temperature range of 84 ¸ 300 K. It was shown that partial substitution of thallium atoms with copper atoms leads to a decrease in the frequencies of the corresponding oscillations in the frequency range of 40-500 cm−1 and does not lead (at these concentrations) to local oscillations. It was found that solid solutions β-Tl1-xCuxInS2 (X=0 ÷ 0.015) exhibit the characteristic single-mode behavior. It was shown that partial substitution of thallium atoms with copper atoms in single crystals β-Tl1-xCuxInS2 (X = 0.005; 0.010; 0.015) weakens the ionic bond in Tl–S, as a result of which the frequencies of “internal” oscillations shift towards low temperatures.

Hydro-flux synthesis and crystal structure of Tl3IO.

Single-crystals of thallium(I) iodide oxide Tl3IO were obtained as by-product in a hydro-flux synthesis at 473 K for 10 h. A potassium hydroxide hydro-flux with a water-base molar ratio of 1.6 and the starting materials TlNO3, RhI3 and Ba(NO3)2 was used, resulting in a few black needle-shaped crystals. X-ray diffraction on a single-crystal revealed the hexa-gonal space group P63/mmc (No. 194) with lattice parameters a = 7.1512 (3) Å and c = 6.3639 (3) Å. Tl3IO crystallizes as hexa-gonal anti-perovskite (anti-BaNiO3 type) and is thus structurally related to the alkali-metal halide/auride oxides M 3 XO (M = K, Rb, Cs; X = Cl, Br, I, Au). The oxygen atoms center thallium octa-hedra. The [OTl6] octa-hedra share trans faces, forming a linear chain along [001]. Twelve thallium atoms surround each iodine atom in an [ITl12] anti-cubocta-hedron. Thallium and iodine atoms together form a hexa-gonal close-sphere packing, in which every fourth octa-hedral void is occupied by oxygen.

Thallium ionic conductivity of new thallium indium hafnium molybdate ceramics

In the process of studying the system Tl2MoO4–In2(MoO4)3–Hf(MoO4)2, a new thallium indium hafnium molybdate was found. The crystal structure of the molybdate Tl5InHf(MoO4)6 was determined in the centrosymmetric space group R $$ \overline{3} $$ c (a = 10.63893 (5) A, c = 38.1447(3) A; V = 3739.04 (4) A3, Z = 6). The structure is a three-dimensional framework consisting of alternating (Hf,In)O6-octahedra connected by МоО4-tetrahedra. Each octahedron has common vertices with tetrahedra. The atoms arranged in this way form channels extended along with the a and b axes, in which thallium atoms are located. The conductivity behavior of Tl5InHf(MoO4)6 ceramics was studied in the temperature range from 300 to 870 K. The conductivity of the heavy cations of thallium is activated with increasing temperature.

Hyperfine structure in thallium atom: Study of nuclear magnetization distribution effects.

The influence of the nuclear magnetization distribution effects on the hyperfine structure of electronic states of thallium atom is studied within the relativistic coupled cluster theory. Relative significance of these effects is demonstrated for the first excited electronic state 6P3/2 of neutral Tl. Based on the obtained theoretical and available experimental data, the nuclear magnetic moments of short-lived 191Tlm and 193Tlm isotopes are predicted: μ191 = 3.79(2) μN and μ193 = 3.84(3) μN, respectively. Using theoretical and experimental data for the neutral Tl, the magnetic anomalies 205Δ203 for the 7S1/2 state of the neutral Tl atom and the 1S1/2 state of the hydrogen-like ion are also predicted.

THE TlPb2Br5–MPb2Br5 (M = K, Rb) SYSTEMS AND CRYSTAL STRUCTURE OF THE K0.45Tl0.55Pb2Br5 PHASE

Physico-chemical interaction in the TlPb2Br5–КPb2Br5 and TlPb2Br5–RbPb2Br5 systems was investigated by XRD and differential thermal analysis methods. Lattice parameters of the samples were calculated using WinCSD software package. Crystallographic parameters were refined using Rietveld method.Phase diagrams of the quasi-binary systems TlPb2Br5–МPb2Br5 (M = K, Rb) were constructed using physico-chemical analysis methods (XRD, DTA). The investigated systems are of eutectic type with the eutectic point coordinates 73 mol.% KPb2Br5, 645 K and 71 mol.% RbPb2Br5, 633 K. The TlPb2Br5–КPb2Br5 system is characterized by the formation below the temperature of the phase transition of TlPb2Br5 of a continuous solid solutions series with the monoclinic structure (S.G. Р21/с). The TlPb2Br5–RbPb2Br5 system features two solid solution ranges, of the low-temperature modification of TlPb2Br5 with the monoclinic structure (S.G. Р21/с) extending to 57 mol.%, and of RbPb2Br5 with the tetragonal structure (S.G. I4/mcm) extending to 21 mol.%.The K0.45Tl0.55Pb2Br5 single crystal was grown by the solution-melt method at a Bridgman-Stockbarger set-up. The upper and lower zone temperatures were 710 K and 570 K, respectively. The temperature gradient at the solid-melt interface was 12 K/cm, and the lowering rate of the container was 8 mm/day.The quaternary phase K0.45Tl0.55Pb2Br5 crystallizes in the NH4Pb2Cl5 structure type (S.G. Р21/с, a=0.92745(8), b=0.83504(7), c= 1.3026(1) nm, β=89.90(2)°). It is formed by the isovalent substitution of thallium atoms by potassium in the TlPb2Br5 structure. All atoms in the structure occupy the 4e sites. However, the partial occupation of the site with Tl and K atoms is 0.55 and 0.45, respectively. The position of K atoms corresponds to the defect position of Tl atoms in the TlPb2Br5 structure. The closest surrounding of Pb1 and Pb2 atoms of eight Br atoms corresponds to the trigonal prism with two additional atoms. Tl atoms coordinate nine Br atoms forming a trigonal prism with three additional atoms against the side faces. The coordination surrounding of K atoms has 6 Br atoms and a neighboring Tl atom forming a trigonal antiprism. This arrangement of the atoms may give rise to new properties of the quaternary phase K0.45Tl0.55Pb2Br5 compared to the original ternary compounds.

Adsorption and Diffusion of Atoms of Groups 1, 2 and 13 Elements on Antimony Telluride Surface

The paper presents ab initio calculations of the adsorption and diffusion of atoms of groups 1, 2 and 13 elements on the (0001) surface of antimony telluride (Sb2Te3) topological insulator. It is shown that most of the investigated adatoms possess minimum energy when occupying the face-centered cubic (FCC) hollow site. Exceptions are presented only for beryllium, boron, indium and thallium atoms which adsorb at the hexagonal close-packed (HCP) hollow site. The adatom diffusion on Sb2Te3 (0001) surface occurs in two stages, i.e. adatoms hop from an FCC site to an HCP site and vice versa. For beryllium, boron, indium and thallium atoms the order of these hops is modified because the HCP hollow site is more favorable location in terms of the absorption energy. The energy barriers are determined for hops on Sb2Te3 (0001) surface, and the obtained hop frquencies are used to analytically calculate the diffusion lengths. The diffusion activation temperature is determined, when the adatom passes through the interatomic spacing of 2.5 A in one minute. It is found that the highest (165 K) activation temperature belongs to beryllium, while the lowest (39 K) corresponds to cesium.

Preparation, electronic structure and piezooptical properties of solid solutions Tl3PbBr5–I

Abstact Phase diagram of the Tl3PbBr5–Tl3PbI5 section of the reciprocal system 2TlI + PbBr2⇔2TlBr + PbI2 was investigated by differential thermal and X-ray phase analysis methods on 18 alloys. The section is quasi-binary, of eutectic type, with the invariant point coordinates 76 mol% Tl3PbI5 and 355 °C. The addition of Tl3PbI5 results in stabilization of the high-temperature (HT) modification of Tl3PbBr5 forming a substitution solid solution, which at room temperature occupies the concentration range of ∼9–71 mol% Tl3PbI5. The solid solution range of low-temperature (LT) Tl3PbBr5 is minor (0–∼6 mol% Tl3PbI5), and that of Tl3PbI5 is in the range of ∼71–100 mol% Tl3PbI5. Tl3PbBr2.5I2.5 crystals were grown by Bridgman-Stockbarger method; they belong to wide-gap semiconductors with Eg decreasing from 2.45 eV at 100 K to 2.36 eV at 300 K. Based on X-ray photoelectron (XP) core-level spectra, one can conclude that the Tl3PbBr2.5I2.5 crystal reveals the XP fine-structure peculiarities well ascribed to thallium, lead, bromine and iodine, constituent atoms of the quaternary halide under consideration. Treatment of the Tl3PbBr2.5I2.5 crystal with 3 keV Ar+ ions reveals that the Pb–I bonds are somewhat weaker in this compound, as compared to the Pb–Br, Tl–Br and Tl–I bonds. Comparison with the similar XP measurements of the related ternary bromide and iodide (Tl3PbBr5 and Tl3PbI5) indicates that the positive effective charge of lead atoms gradually decreases when going from Tl3PbBr5 to Tl3PbBr2.5I2.5 and, further, to Tl3PbI5, while the charge state of thallium atoms does not change in the above sequence of compounds. In the sequence Tl3PbBr5 → Tl3PbBr2.5I2.5 → Tl3PbI5 the relative peak intensity of the XP valence-band spectrum monotonously decreases. The laser stimulated piezooptics at 1150 nm excited by 1540 nm Er:glass nanosecond laser and its second harmonic generation are reported.

Relativistic coupled-cluster calculations of the polarizabilities of atomic thallium

Using the relativistic coupled-cluster method, we calculate the static dipole polarizabilities of the $6p$, $7s$, $7p$, $8s$, $8p$, and $6d$ states and the dynamic dipole polarizabilities of the $6p$ and $7s$ states of the thallium atom. The trivalent thallium atom is computationally treated as a monovalent system, together with all linear and nonlinear terms of single- and double-cluster operators included in the correlation calculations. We observe that the dominating contributions to the static scalar polarizabilities of the $7{s}_{1/2}$, $7{p}_{1/2}$, $8{p}_{1/2}$, and $8{p}_{3/2}$ states are from one or two specific transitions. The matrix elements of these specific transitions can be determined by combining the experimental values of relevant static scalar polarizabilities. A number of magic wavelengths for the $6{p}_{1/2}$--$7s$ and $6{p}_{3/2}$--$7s$ transitions in the range of 488--1300 nm and the longest tune-out wavelength of the ground state are determined. These magic wavelengths and tune-out wavelength may be useful for further thallium experiments. Experimental measurements of the magic wavelengths near 1245 nm would give estimates of the $7{s}_{1/2}$--$7{p}_{1/2}$ and $7{s}_{1/2}$--$7{p}_{3/2}$ transition matrix elements and their ratio. Furthermore, lifetimes of many excited states, as well as the Stark-induced scalar and vector dipole polarizabilities for the $6{p}_{1/2}$--$7{p}_{1/2}$ transition, are also evaluated and compared with available theoretical and experimental values.

Interaction between Thallium and the Au(111) Surface. Quantum-Chemical Analysis

The interaction between thallium atoms and the Au(111) surface is studied using the cluster metal surface model and the density functional method. An adsorbed thallium atom forms a strong chemical bond with surface gold atoms. The adsorption energy barely depends on the location of the thallium atom. The electron density is appreciably displaced from thallium to gold in the process of adsorption. Thallium exists on the surface in the cationic form. The analysis of the density of state (DOS) spectra demonstrates that the atomic orbitals of thallium participate in the formation of lower molecular orbitals in the thallium–gold system when the surface is slightly filled with thallium. When the surface is filled to a substantial degree, the contribution of thallium to the molecular orbitals with the least negative energy appreciably grows. The possible change in the electronic work function upon the surface modification of gold with the adsorbed thallium is estimated.

Electronic structure and basic optical constants of TlHgBr3: Density functional theory calculations

We provide data of density functional theory (DFT) calculations of total and partial densities of states of TlHgBr3 using the method of augmented plane wave–local orbitals. The calculated density of states yields information regarding hybridization between the electronic states and on the chemical bonding of TlHgBr3. The DFT calculations predict that the principal contributors to the valence band (VB) of TlHgBr3 are 4p electronic states of bromine atoms at the central and upper regions of the band, with their slightly smaller input in other VB regions. Substantial contributions of 6s electronic states of thallium atoms lie at the upper part and bottom of the VB, and 6s states of mercury atoms occupy the bottom attributing to a specific electronic structure of TlHgBr3. The unoccupied Hg 6s electronic states, with somewhat lesser input of the unoccupied Br 4p states, contribute to the lower part of the conduction band (CB) of TlHgBr3. The theoretically derived electronic band structure demonstrates that the CB minimum and the VB maximum are positioned at the point Z of the Brillouin zone denoting a direct nature of band gap. Basic optical constants of TlHgBr3 are explored in the present work in relation to calculated electronic band structure.

Two-component relativistic coupled-cluster methods using mean-field spin-orbit integrals

A novel implementation of the two-component spin-orbit (SO) coupled-cluster singles and doubles (CCSD) method and the CCSD augmented with the perturbative inclusion of triple excitations [CCSD(T)] method using mean-field SO integrals is reported. The new formulation of SO-CCSD(T) features an atomic-orbital-based algorithm for the particle-particle ladder term in the CCSD equation, which not only removes the computational bottleneck associated with the large molecular-orbital integral file but also accelerates the evaluation of the particle-particle ladder term by around a factor of 4 by taking advantage of the spin-free nature of the instantaneous electron-electron Coulomb interaction. Benchmark calculations of the SO splittings for the thallium atom and a set of diatomic 2Π radicals as well as of the bond lengths and harmonic frequencies for a set of closed-shell diatomic molecules are presented. The basis-set and core-correlation effects in the calculations of these properties have been carefully analyzed.

The Excitation of Rydberg Atoms of Thallium in an Electric Field

The spectrum of excitation of Rydberg states of thallium atoms has been investigated using a collimated atomic beam in a two-step isotope selective laser scheme 62P1/2 → 62D3/2 → Tl** in the presence of an electric field with a strength of up to 1.5 kV/cm near the level 16F5/2. The optical transitions 6D3/2 → 18D3/2 and 6D3/2 → 16G7/2, which were induced by an external electric field and dipole-forbidden, have been studied experimentally. The values for the scalar polarizabilities (in units сm–1/(kV/сm)2) α0(16F5/2) = 3.71 ± 0.3, α0(18D3/2) = 11.70 ± 0.25, and α0(16G7/2) = 44.1 ± 0.9, which are compared with the calculated one, have been obtained. The new values of energy parameters for the states 18D3/2 and 16G7/2 have been determined.

Tl2Ag12Se7: A New pnp Conduction Switching Material with Extraordinarily Low Thermal Conductivity

While continuing our investigations of thallium chalcogenides because of their outstanding thermoelectric properties, we discovered a new selenide with an interesting pnp switching behavior around 400 K. Tl2Ag12Se7 was prepared via high temperature reaction from the elements in the stoichiometric ratio. This selenide crystallizes in a new structure type, namely a √3 × √3 × 1 super cell of the Zr2Fe12P7 type, adopting space group P3, a = b = 18.9153(18) A, c = 4.3783(4) A, and V = 1356.6(2) A3 (Z = 3). The structure consists of a complex network of three-dimensionally connected AgSe4 tetrahedra that include linear channels filled with thallium atoms. This material is a semiconductor with an experimentally derived activation gap of 0.8 eV and extraordinarily low thermal conductivity of <0.45 W m–1 K–1. A reversible phase transition causes a pnp switch from p-type to n-type and back to p-type conduction beginning around 390 K, with the thermopower changing fast from +230 μV K–1 at 390 K to −230 μV K–1 at 41...

A new telluride topology: the crystal structure of honeaite Au3TlTe2

AbstractThe crystal structure of the first thallium-bearing gold telluride, honeaite Au3TlTe2, is reported and its topological novelty discussed. Honeaite is orthorhombic, space group Pbcm and unit-cell parameters a = 8.9671(4), b = 8.8758(4), c= 7.8419(5) Å, V = 624.14(6) Å3 (Z = 4). Its structure has been refined to R1 = 0.033, wR2 = 0.053, Goof = 1.087. The structure is based upon a corrugated double-sheet comprising two sub-sheets, each composed of six-memberedrings of corner-linked TeAu3 pyramids in which the Te lone pair is stereoactive. Rows of thallium atoms lie in the grooves between sheets and provide the only inter-sheet connectivity via Tl-Au bonds. There is extensive Au-Au bonding linking the two sub-sheets of the double-sheet.The structure is distinct from those of the 1:2 (Au,Ag)-tellurides: calaverite AuTe2, sylvanite AuAgTe4 and krennerite Au3AgTe8, which are based upon sheet structures with no connecting inter-sheet atoms. It also differs fundamentally from the structuresof synthetic phases Ag3TlTe2 and Ag18Tl4Te11, both of which have an analogous stoichiometry. In contrast to the pyramidal TeAu3 group of honeaite and krennerite, Ag does not form the corresponding TeAg3 group in itstellurides.