Thallic Oxide Research Articles

Nature of the band gap ofTl2O3

The ground state electronic structure of thallic oxide has been a source of controversy in the literature, with Tl${}_{2}$O${}_{3}$ reported to be either a degenerate $n$-type semiconductor or an intrinsic semimetal with no band gap. Using a screened hybrid density functional theory (DFT) approach, we show that Tl${}_{2}$O${}_{3}$ is a semiconductor with a predicted band gap of 0.33 $\mathrm{eV}$. We rationalize the large optical band gaps reported in experimental studies and demonstrate that previous ``standard'' DFT approaches wrongly predict Tl${}_{2}$O${}_{3}$ to be a semimetal. Doubly ionized oxygen vacancies are shown to be the origin of the high carrier concentrations seen experimentally.

Epitaxial electrodeposition of thallic oxide on single crystal gold

Thin films of thallic oxide Tl 2O 3 (Ia3, a=1.0534 nm) were electrodeposited on the three low-index surfaces of single crystal Au (Fm3m, a=0.4079 nm). Epitaxial films of Tl 2O 3 with a strong out-of-plane (100) texture were obtained in the case of the (100) and (111) Au substrates, while the film on the (110) Au substrate did not show a preferred out-of-plane orientation. Studies of the in-plane orientation of the films revealed that the large lattice mismatch between Au and Tl 2O 3 is accommodated by the formation of the coincidence lattices on (100) and (111) Au.

Conductivity and photoelectric response of electrodeposited thallic oxide films

Highly conductive polycrystalline and amorphous Tl 2O 3 films are prepared by electrodeposition method. The resistivity of the polycrystalline film is lower than that of the amorphous one. A resisitivity of only 3.2×10 -4 Ω cm was obtained for the polycrystalline film. It is found that the electrodeposited Tl 2O 3 films exhibit photoelectric response of n-type semiconductors. This photoelectric response may find use for further application of the Tl 2O 3 films.

Analytical Applications and Catalytic Activities of Electrodeposited Thallic Oxide Films

Abstract Thallic oxide (Tl2O3) were electrodeposited onto indium tin oxide (ITO) conducting glass substrates in alkaline solutions. It has a high catalytic activity for the anodic oxidation of sulfite (SO32−) and thiosulfate (S2O32−) anions. Also it can be used for electroanalysis of nitrite ions (NO2−) with an excellent stability and a detection limit of 4.0 × 10−6 mol/dm3.

The structure and electrical properties of lithium borate glasses containing thallic oxide

Lithium borate glasses containing were prepared and annealed. The results of deconvolution analysis of infrared spectra, molar volume and electrical conductivities (DC and AC) show that thallium ions are distributed as network formers in the glass matrix. The analysis of IR spectra shows that the formation of tetrahedral groups is not affected by the addition of ions and that ions are associated between and to convert them to and units. The introduction of ions into lithium borate glasses causes a decrease in the conductivity while the associated activation energy increases.

Rapid Determination of Metal Particles on Air Sampling Filters Using Laser-Induced Breakdown Spectroscopy

A preliminary investigation of an alternative method of analysis for metal particles is presented. The mass of thallium (TI) particles on filters was determined in less than 1 minute using the technique of laser-induced breakdown spectroscopy (LIBS).Thallium was collected by passing contaminated air through a filter or by wiping a TI-contaminated surface with a filter. The particles (<20 µm diameter) were in the form of thallic oxide used in the manufacture of superconducting metals. Thallium was detected by forming a series of laser sparks across the filter surface. The sparks vaporized the particles and excited the resulting atoms. Thallium was detected by temporally and spectrally resolving the spark light. The detection limit for TI was 40 ng/cm2 on a filter surface. The useful dynamic range extends from 0.2 to 40 µg/filter using the strong 535.05 nm neutral TI emission line. The LIBS method of detection is intended to supplement (rather than replace) conventional analytical methods such as atomic abs...

An Investigation of Electrochemical Properties for Thallic Oxide/Thallous Ion Couple in a High Temperature Aqueous System

Electrochemical properties of thallic oxide have been studied in high temperature water (275°C). The overall electrochemical reaction for the equilibrium potential was elucidated by electrochemical techniques and x‐ray diffraction analysis. The electrode potential dependencies on both pH and thallous ion activity were consistent with those predicted by thermodynamic data. The x‐ray diffraction pattern of the product from anodic electrolysis of the thallous ion was consistent with that of the standard for thallic oxide. The thallic oxide electrode gives the thermodynamic potential, and can be employed for measuring electrochemical potential.

NMR Study of Metallic Thallic Oxides; Tl2O3-δ

Thallic oxide, Tl 2 O 3-δ , an oxide with high conductivity, has been investigated using the pulsed NMR method. The shift and spin-lattice relaxation time ( T 1 ) measured for 205 Tl nuclei showed Korringa-like behavior, but their values were found to be strongly sample dependent. This suggests that the carriers belong to the thallium 6s band, and that the materials which we regard as Tl 2 O 3 are not stoichiometric and deficient in oxygen.

Kinetics and Mechanism of the Ruthenium, Osmium and Neodymium Catalysed thallic Oxidation of 2,4-Diamino-4-Oxobutanoic Acid in Perchloric Acid Medium

Kinetics and Mechanism of the Ruthenium, Osmium and Neodymium Catalysed thallic Oxidation of 2,4-Diamino-4-Oxobutanoic Acid in Perchloric Acid Medium

Kinetics and Mechanism of the Ruthenium, Osmium and Neodymium Catalysed thallic Oxidation of 2,4-Diamino-4-Oxobutanoic Acid in Perchloric Acid Medium

Kinetics and Mechanism of the Ruthenium, Osmium and Neodymium Catalysed thallic Oxidation of 2,4-Diamino-4-Oxobutanoic Acid in Perchloric Acid Medium

Anodic oxidation — an improved technique in the chemical recovery and refinement of isotopic thallium

The Electromagnetic Isotope Separations Program of the Oak Ridge National Laboratory has been involved in the seperation, chemical recovery and refinement of the stable isotopes of thallium since 1947. The initial interest was in obtaining chemically pure, isotopically enriched samples of each of the stable isotopes of thallium for basic physical research. Recently, the major emphasis has shifted to 203Tl which is used to produce the radiopharmaceutical isotope 201Tl. Two persistent problems in the chemistry of isotopic thallium have been the production of unoxidized, homogeneous ingots of thallium metal and the elimination of sulfur contamination in thallic oxide. The application of anodic oxidation in the chemistry has resulted in a significant reduction of the problems previously encountered as well as considerable improvement in the chemical purity of the product. The details of this procedure and a general description of all of the appropriate thallium chemistry will be presented. In addition, the generalization of the technique to the refinement of other elements will be discussed.

Some studies on thallium oxalates. I. Thermal decomposition of ammonium bisoxalatothallate(III)

Trivalent thallium is precipitated in the presence of 0.1 M HNO 3 (or 0.05 M H 2SO 4) and O.1 M NH 4NO 3 (or 0.05 M (NH 4) 2SO 4) with oxalic acid. The chemical analysis of the salt obtained correspondens to the formula, NH 4[Tl(C 2O 4) 2]·3H 2O. The thermal decomposition studies of the complex indicate the formation of the intermediates ammonium thallous oxalate (stable from 150° to 160°C) and thallous oxalate (stable up to 290°C) and the final product to be a mixture of 25% of thallous oxide and 75% of thallic oxide (stable from 450° to 650°C). The infrared absorption spectra, X-ray diffraction patterns, microscopic observations and the electrical resistance measurements are used to characterise the complex and the intermediates of its thermal decomposition.

Organothallium Compounds. XV. Thallation of Polyfluoroaromatic Compounds

Thallic trifluoromethanesulfonate has been prepared by reaction of trifluoromethanesulfonic acid with either thallic oxide or solutions of thallic trifluoroacetate in trifluoroacetic acid, and has been isolated as the trihydrate on crystallization fromnitromethane. The polyfluoroarenes,p-CH3OC6F4H, p-CH3C6F4H, m-H2C6F4, o-H2C6F4, p-H2C6F4, C6F5H, 1,3,5-F3C6H3 or 1,2,4-F3C6H3, have been thallated by thallic trifluoromethanesulfonate in trifluoroacetic acid, giving the corresponding poly- fluorophenylthallium(III) bis(trifluoromethanesulfonates), which have been characterized spectroscopically and by conversion into the corresponding (polyfluoro)iodobenzenes on treatment with sodium iodide. Only slight thallation of m-BrC6F4H and m-O2NC6F4H was observed. By contrast with thallic trifluoromethanesulfonate, thallic trifluoroacetate in trifluoroacetic acid induced little thallation of the most reactive polyfluorobenzene, p-CH3OC6F4H. Thallic trifluoromethanesulfonate also thallated p-CH3OC6F4H in nitromethane, sulfolane, and with the substrate as solvent, but p-CH3C6F4H failed to react. Treatment of the polyfluorophenylthallium(III) bis(trifluoromethane- sulfonates) with boiling aqueous sodium acetate caused symmetrization into the corresponding acetatobis(polyfluorophenyl)thallium(III) compounds. A similar reaction between 2,4,6-trifluoro- phenylthallium(III) bis(trifluoromethanesulfonate) and sodium acetate at room temperature yielded 2,4,6-trifluorophenylthallium(III) diacetate. 2,3,4,6-Tetrafluorophenylthallium(III) bis(trifluor0- methanesulfonate) was converted by boiling water into bis(2,3,4,6-tetrafluorophenyl)thallium(III) trifluoromethanesulfonate.

Electrical Conduction in Single‐Crystal Thallic Oxide: I, Crystals “As‐Grown” from the Vapor in Air

Thallic oxide, “T12O3,” has been shown to be a degenerate n‐type semiconductor with resistivity varying from 60 to 150 μΩ‐cm over the range 4° to 900°K. The carrier concentration was 7 × 1020 cm−3 and is temperature independent. Room‐temperature Hall mobility was 105 cm2 V−1 s−1, increasing to 130 cm2 V−1 s−1 below 70°K. Donor states were shown to be native defects, probably oxygen vacancies.

Electrical Conduction in Single‐Crystal Thallic Oxide: II, Effects of Annealing at 923°K in Oxygen Pressures from 0.01 to 1 Atmosphere

The low‐temperature conductivity of thallic oxide (Tl2O3) is relatively insensitive to the equilibrium partial pressure of oxygen during annealing at 923°K, i.e. the maximum variation is ∼15% over the range of 0.01 to 1 atm O2, with a relative maximum occurring at ∼0.2 atm. The insensitivity in conductivity results from the compensating effects of increasing mobility and decreasing carrier concentration with increasing oxygen pressure during annealing. At low oxygen pressures, defect interactions complicate the interpretation of the measurements, but a calculated Fermi energy on the order of 0.8 eV is sufficiently close to other reported values to confirm the model of a highly degenerate semiconductor with a simple S‐like conduction band described by a parabolic density‐of‐states function.

Thermal behaviour of thallous perchlorate

Thermal decomposition characteristics of thallous perchlorate are investigated in nitrogen and in air using TG and DTA techniques. Isothermal studies at 380°, 400°, 420° and 440° in air and in nitrogen showed that the relative amounts of the decomposition products, namely, thallic oxide and thallous chloride, depend upon both the temperature and the atmosphere around the sample. At low pressures (5×10−1 mm/Hg) there is volatilization of thallous perchlorate even at 200°.

Ring C Functionalized Diterpenoids. Part IV. Minor Products from the Cleavage of the Cyclopropane Ring in Methyl ent-Trachyloban-19-oate with Thallic Acetate

Structures are assigned to seven minor products (6b, 9, 11b, 12b, 13b, 16, and 25b) obtained from treatment of methyl ent-trachyloban-19-oate (1) with thallic oxide in acetic acid. The mechanism of the oxidative cleavage is discussed. Formation of the major products, described earlier, and all but one (25b) of the minor products may be rationalized in terms of initial scission of the C13—C16 bond.

Mitochondrial modification and respiratory deficiency in the yeast cell caused by cadmium poisoning

Cells of Fleischmann bakers' yeast were grown in standard nutrient broth and in broth to which cobalt, or cadmium, or thallium, had been added. The cells were fixed by glutaradehyde-permanganate and sectioned. Electron microscopy showed that ( a) the endoplasmic reticulum was fixed well in cells grown in cobalt or cadmium, but the endoplasmic reticulum was not fixed in cells grown in normal or thallium broth; ( b) the cristate mitochondria were normal in all cells except those grown in cadmium. No cristae were visible in the “cristate” mitochondria of cells grown in cadmium broth; ( c) a large fraction of the cells recovered from cadmium broth were respiratory-deficient; ( d) thallic oxide was present in the cristate mitochondria of cells recovered from thallium broth.

Mitochondrial modification and respiratory deficiency in the yeast cell caused by cadmium poisoning

Cells of Fleischmann bakers' yeast were grown in standard nutrient broth and in broth to which cobalt, or cadmium, or thallium, had been added. The cells were fixed by glutaradehyde-permanganate and sectioned. Electron microscopy showed that ( a ) the endoplasmic reticulum was fixed well in cells grown in cobalt or cadmium, but the endoplasmic reticulum was not fixed in cells grown in normal or thallium broth; ( b ) the cristate mitochondria were normal in all cells except those grown in cadmium. No cristae were visible in the “cristate” mitochondria of cells grown in cadmium broth; ( c ) a large fraction of the cells recovered from cadmium broth were respiratory-deficient; ( d ) thallic oxide was present in the cristate mitochondria of cells recovered from thallium broth.

The catalytic oxidative dimerization of propylene

Studies have been made of the catalytic oxidation of propylene to hexadiene over thallium oxides. The reaction is selective to the 1,5-diene, the only other product being carbon dioxide which originates from the overoxidation of the hexadiene. The active component has been found to be the thallic oxide, which is reduced during the course of the reaction. Permanent deactivation of the catalyst, which occurs if thallous salts distil out of the reactor, may be avoided if sufficient oxygen is present to rapidly reoxidize the catalyst. The production of hexadiene is favored at high temperatures, although the catalyst may deactivate faster under these conditions. A reaction mechanism is proposed in which the high selectivity to the 1,5-dimer is explained in terms of the simultaneous donation of two electrons to a Tl 3+ ion.