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The mixing behaviour of Cd-Tl, In-Tl and Sn-Tl liquid alloys have been examined using formalism that relates viscosity and chemical diffusion with thermodynamic properties. We found that the atomic interactions in these systems are weak; Cd-Tl has the weakest atomic interactions, while the interactions in Sn-Tl are weaker than in In-Tl. Also, the systems exhibit weak homocoordination tendency; Cd-Tl is the most homocoordinated when C, while Sn-Tl is the most homocoordinated when C. Additionally, enthalpic and entropic effects significantly influenced the viscosity of Cd-Tl in the entire thallium composition but only influenced the viscosities of In-Tl and Sn-Tl in some thallium compositions. Furthermore, the atomic size difference has the most pronounced effect on the viscosity of Cd-Tl, while it has more effect on the viscosity of In-Tl than on the viscosity of Sn-Tl. This study provides useful insight on the structure and binding in three thallium-based alloys. [ABSTRACT FROM AUTHOR]

The new mixed compound Tl 1.90 Rb 0.10 (SO 4 ) 0.92 (SeO 4 ) 0.08 Te(OH) 6 (TlRbSSeTe) has been synthesized in order to determine the temperature transitions and to specify the electrical properties as well as the conduction mechanism. It is obtained by slow evaporation at room temperature and prove to crystallize in the monoclinic system with P 2 1 / c space group using X-ray diffractometer data. The basic property of these atomic arrangements is the coexistence of three different anions ( SO 4 2 − , SeO 4 2 − and TeO 6 6 − groups) in the unit cell, related by O−H…O hydrogen bonds building up the crystal. Thermal analysis (DSC, DTA and TG) of the title compound confirms the presence of the phase transitions and the temperature of the decomposition of the studied salt. In order to characterize the phase transitions, Raman spectra have been recorded at various temperatures in the wavenumber range from 50–1200 cm −1 . Detailed dielectric and electrical properties of the material have been analyzed as a function of frequency (100 Hz–10 MHz) and temperature (383–518 K). Besides, the analysis of Nyquist plots were well fitted to an equivalent circuit consisting of a series of combination of grains and grain boundary elements. The variation of the DC and AC conductivity confirms all the transitions of our sample. Furthermore, The frequency dependence of alternative current (AC) conductivity is interpreted in terms of Jonscher's law (developed). The alternative current (AC) electrical conduction in TlRbSSeTe material is accounted for in terms of two processes that can be assigned to a hopping transport mechanism. These processes are the correlated barrier hopping (CBH) model in some regions, as well as the non-overlapping small polaron tunneling (NSPT) model in the other regions. The conduction mechanism for each phase is determined with the help of Elliot's theory. [ABSTRACT FROM AUTHOR]

The paper describes the determination of bromide by evaluating the molecular absorption of thallium mono-bromide (TlBr) at the rotational line at 342.9815 nm by making use a high-resolution continuum source graphite furnace atomic absorption spectrometer. The effects of variables such as the wavelength, graphite furnace program, amount of Tl and the use of a modifier were investigated and optimized. Various chemical modifiers have been studied, such as Pd, Mg, Ag and a mixture of Pd/Mg. It was found that best results were obtained by using Ag which prevents losses of bromide during pyrolysis step through precipitation of bromide as AgBr. In this way, a maximum pyrolysis temperature of 400 °C could be used. The optimum molecule forming temperature was found to be 900 °C. Bromide concentrations in various water samples (CRM, bottled drinking water and tap water) were determined. The quantification was made by both linear calibration and standard addition techniques. The results were matched well those of the reference method. The calibration curve was linear in the range between 1 and 1000 ng Br with a correlation coefficient R = 0.999. The limit of detection and characteristic mass of the method were 0.3 ng and 4.4 ng of Br. [ABSTRACT FROM AUTHOR]

Spectroscopic, thermal and fluorescence properties of various thallium and tin complexes, X-Tl(III)t(4-Y)PP and X-Sn(IV)t(4-Y)PP where X = 5-SOH-2-OHOCH,(5-SSA); 5-Cl-2-OHOCH,(5-CSA); and 5-NH-2-OHOCH,(5-NSA) and Y = -Cl, -OCH, are investigated in detail. Analysis of the spectral data [IR, UV-Vis and NMR (H and Sn)] of complexes suggests that the two trans-axial ligands are strongly bound in a symmetric manner at the tin center in these complexes. Whereas the absorption and emission studies of thallium complexes characterized the sitting-Atop (SAT) feature of the complexes, the fluorescence lifetime of the tin complexes is found to be higher than thallium complexes. The structure and morphology of complexes were studied by X-ray powdered diffraction analysis. From the X-ray diffractograms, it could be revealed that the complexes are crystallized in mixed crystalline forms. Thermal studies of these porphyrins were carried out in an argon atmosphere from room temperature to 800 °C using thermal analyzer. Evaluation of the thermal analysis of the two metal complexes reveals that the tin(IV) porphyrin complexes are more stable than thallium(III) complexes. Some of the synthesized complexes of thallium and tin have been screened for biological activity against B. subtilis, M. luteus, S. aureus, P. florescens and E. coli by agar well diffusion methods that were found to be inactive against bacterial strains. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Thallium is a non essential and highly toxic metal listed by USEPA and the European Water Framework Directive as a priority pollutant. It is present in the environment mainly as Tl(I) and Tl(III) usually at very low concentrations, which makes it a challenging element requiring high sensitive instrumental techniques to measure it in complex matrices. The average concentration of thallium in the Earth's crust is generally below 1 ppm and its geochemical behaviour and mobility is often compared to that of potassium. In non-contaminated freshwater, the thallium concentration is generally below 1 μg/L and rarely exceeds 20 ng/L in the open ocean. The affinity of thallium for iron and manganese oxyhydroxides is often observed in soil and sediment where its concentrations normally remain in the low ppm except for mine and contaminated areas. Thallium is present at low ng/m 3 in aerosols and air particulates but can increase to higher levels in highly urbanized areas and in mining and industrialized zones. For this review, more than 285 papers containing information of thallium in natural waters, soils, sediments and air particulates have been consulted but only a low number of them present information on the speciation of the metal. [ABSTRACT FROM AUTHOR]

In the present work, details of the crystal growth (Bridgeman method) and optical reflection spectroscopy for two single crystals (X = S, Te) were reported. Detailed ab-initio DFT calculations of the structural, electronic and optical properties of the crystals were performed for a deeper understanding of the experimentally obtained optical data. The special attention is paid to the electron charge density distribution, carrier mobility, optical reflectivity spectra and finally the anisotropy of the corresponding optical functions were studied. Were established a relations with carrier mobility, the optical anisotropy and electronic band structures for the titled crystals and compared with the optical reflectance spectra, covering the range of principal inter-band transitions. The origin of the calculated bands and effects of the anion substitution (Se by Te) on the crystal properties are studied. The role of screening effects is discussed by a comparison of the GGA and LDA approaches, including the electronic band dispersion and effective masses anisotropy. The possible changes of the inter-band transition are considered. The relation between the space charge density distribution and optical features is established. Finally was explained the origin of the observed discrepancies between the experimental and theoretical data. [ABSTRACT FROM AUTHOR]

We have studied the vortex dynamics of the Tl KFeSe single crystal through the measurements of temperature and magnetic field dependencies of electrical resistivity. Due to the existence of intra-layer Fe-site vacancy and inter-layer Josephson coupling, it is found that the pinning of vortices is very strong, which hinders the flux flow. A very high upper critical field H value and a moderate anisotropy parameter γ are obtained, similar to those found in YBaCuO superconductor. These results suggest that the Tl KFeSe superconductor has a good sustainability under high magnetic field, indicating a good potential for application. [ABSTRACT FROM AUTHOR]

Trap centers in TlGaInS single crystals have been investigated by thermoluminescence (TL) measurements in the temperature range of 10-110 K. Curve-fitting method was utilized to evaluate the activation energies (12 and 26 meV) of revealed two trap centers. Thermal cleaning method was applied to the spectra and two overlapping peaks were reduced to one single peak corresponding to deeper trap level. The characteristics of heating rate dependence and trap distribution of the separated peak have been studied using experimental techniques based on various heating rates and various illumination temperatures, respectively. Anomalous heating rate dependence was observed carrying out TL measurements with various heating rate between 0.2 and 1.2 K s. This behavior was explained on the base of a semi-localized transition model. Moreover, increase of activation energy from 27 to 67 meV was revealed for the applied illumination temperature range of 26-36 K. [ABSTRACT FROM AUTHOR]

Structural and electronic properties of zinc blende TlxIn1-xN alloy have been evaluated from first principles. The band structures have been obtained within density functional theory (DFT) with the modified Becke-Johnson (MBJLDA) approach for the exchange-correlation potential, and atoms represented by the fully relativistic pseudopotentials. The calculated band-gap dependence on Tl content in this hypothetical alloy exhibits a linear behavior up to the 25% of thallium content where its value approaches zero. In turn, the split-off energy at the Γ point of the Brillouin zone, related to the spin-orbit coupling, is predicted to be comparable in value to the band-gap for relatively low thallium content of about 5%. These findings point to TlxIn1-xN alloy as a promising material for optoelectronic applications. Furthermore, the band structure of TlN reveals some specific properties exhibited by topological insulators. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Tl–TlTe–I system is investigated. [•] The fields of primary crystallization are determined. [•] Homogeneity range for Tl5Te3−xI x solid solution is established. [•] The partial molar thermodynamic functions of Tl in Tl5Te3−xI x are calculated. [•] Standard integral thermodynamic functions of Tl5Te3−xI x are calculated. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, annealing was carried out in air after cutting, polishing and etching to eliminate defects introduced by crystal and wafer preparation work. The effect of annealing temperature and time on the properties of TlBr crystals was investigated. The crystal quality was characterized by infrared (IR) transmittance spectrum, I–V measurement, XRD and energy response spectrum. In the annealing temperature range (100–320°C) applied, it was found that higher temperature was more effective for improving quality. Furthermore, it is proved that an appropriate annealing time is vital for better crystal quality. [Copyright &y& Elsevier]

Highlights: [•] The magnetic behavior of Tl9CeTe6, Tl9PrTe6, Tl9TbTe6, Tl9SmTe6, is presented. [•] All samples are paramagnetic at low magnetic fields. [•] The Ce representative stands out with different thermoelectric properties and lower unit cell volume. [•] Fitting the magnetic susceptibility data reveals the existence of mixed valent cerium. [Copyright &y& Elsevier]

Highlights: [•] The Tl2Te–TlBr–TlI system is investigated. [•] The fields of primary crystallization are determined. [•] Formation of the unlimited Tl5Te2I1−x Br x solid solution is established. [•] The partial molar thermodynamic functions of Tl in Tl5Te2Br x I1−x are calculated. [ABSTRACT FROM AUTHOR]

The study of multi-component systems without exact knowledge of the binary phase diagrams and their thermodynamic properties leads to erroneous results of such systems. This work is devoted to a critical analysis of binary thallium-selenium, and thalliumtellurium systems, and presents a continuance of the thermodynamic analysis of the phase diagram of thallium-sulfur system*). Thallium chalcogenides and their derived materials with other elements at the solid, liquid and glassy states have a wide range of properties for use in industry. The knowledge of thermodynamic properties and phase diagrams of binary, ternary and many component systems is necessary for solving material science problems and for designing new products and technologies fitted to actual needs. [ABSTRACT FROM AUTHOR]

Single crystals of the previously unknown thallium silicate T14Si5O12 Have been prepared from hydrothermal crystallization of a glassy starting material at 500 °C and lkbar. Structure analysis resulted in the following basic crystallographic data: monoclinic symmetry, space group C2/c, a = 9.2059(5) Å, b = 11.5796(6) Å, c = 13.0963(7) Å, β = 94.534(5)°. From a structural point of view the compound can be classified as an interrupted framework silicate with Q3- and Q4-units in the ratio 2:1. Within the framework 4-, 6-, and 12-membered rings can be distinguished. The framework density of 14.4 T-atoms/1000 Å3 is comparable with the values observed in zeolitic materials like Linde type A, for example. The thallium cations show a pronounced one-sided coordination each occupying the apex of a distorted trigonal T1O3 pyramid. Obviously, this reflects the presence of a stereochemically active 6s2 lone pair electron. The porous structure contains channels running along [110] and [–1 1 0], respectively, where the T1+ cations are located for charge compensation. Structural investigations have been completed by Raman spectroscopy. The interpretation of the spectroscopic data and the allocation of the bands to certain vibrational species have been aided by DFT calculations, which were also employed to study the electronic structure of the compound. [ABSTRACT FROM AUTHOR]

Abstract: The formation of nitrogen-induced defects and the reduction of their concentration after rapid thermal annealing in TlInGaAsN alloy system are studied in detail, employing the photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) studies. XPS analysis revealed that the N-induced defect configurations are most likely attributed to the N–As spilt interstitials and (NAs–AsGa) nearest neighbor pairs. Rapid thermal annealing (RTA) treatment reduces the defect concentration and induces a significant improvement in the PL efficiency of the TlInGaAsN material system. [Copyright &y& Elsevier]

Abstract: In this study, effects of the vanadium substitution for Ca sites on the Tl-2223 superconductor have been studied. The samples with nominal composition Tl2Ba2Ca2−x V x Cu3O y (x=0.0, 0.1, 0.3, 0.5, 0.7) have been prepared by the solid-state reaction method. The obtained samples have been characterized by x-ray diffraction, scanning electron microscope and the superconductivity of these samples have been investigated by electrical resistivity. X-ray powder diffraction pattern showed that there are some impurity phases as well as Tl-1223 main phase. Although the critical temperature (T c ) has increased for the first two substitution values, for the last two substitution values T c has decreased. Higher amounts of vanadium substitution have caused non-superconductor. As a result, low vanadium substitution for Ca sites improved the Tl-2223 superconducting properties. [Copyright &y& Elsevier]

A study of the corrosion-electrochemical and thermal properties of the thallium-alloyed Al + 2.18% Fe alloy demonstrated that the corrosion potential of the alloy can be raised and the heat conductivity be improved. [ABSTRACT FROM AUTHOR]

In this paper, an effective method for improving emissions from Josephson junction arrays was proposed. We took the substrate as a dielectric resonance antenna to improve the coupling of intrinsic junctions to electromagnetic waves. Electromagnetic simulations were performed in parallel with experiment investigations. Sharp radiation peaks at 76.9 GHz were detected from intrinsic Josephson junction arrays in misaligned TlBaCaCuO thin films at 78 K. Experimental results proved the effectiveness of this method, which offered a competitive choice for coherent emission from intrinsic Josephson junction arrays. [ABSTRACT FROM AUTHOR]

Abstract: The temperature effects on the capacitance–voltage characteristics as well as the room temperature capacitance–frequency characteristics of TlGaTe2 crystals are investigated. A very wide range of linearly varying tunable capacitance from 6.0μF to 60pF was recorded. The capacitance–voltage characteristics, being recorded in the temperature range of 290–380K, revealed a linear increase in the build in voltage associated with exponential decrease in the density of non-compensated ionized carriers with increasing temperature. The high temperature (up to 380K) biasing ability, the linear tunability and the high dielectric constant values (∼103) make the TlGaTe2 crystals applicable in microelectronic components. [Copyright &y& Elsevier]

A series of single-phase polycrystalline (TlSbTe2)x(Tl0.02Pb0.98Te)1-x (x=0, 0.05,0.1) compounds were made to reduce thermal conductivity while maintaining the enhanced Seebeck coefficients found in PbTe doped with Tl. Transport property measurements confirmed that high Seebeck coefficients from doping with Tl are retained by alloying with TlSbTe2. At the same time, a thermal conductivity as low as 0.8 W/mK at room temperature, and 0.6 W/mK at 673 K was observed, corresponding to a 30% reduction in lattice thermal conductivity at 673 K compared with 2%Tl-PbTe. However, the maximum zT in this system is 0.8 (at 623 K), which is lower than that of 2%Tl-PbTe prepared in this work (1.2 at 673 K) owing to a decrease of the charge-carrier mobility when alloying with TlSbTe2. Possible influences on the mobility are discussed. [ABSTRACT FROM AUTHOR]

Zimmer and collaborators have recently proposed an alternative approach to Landau's for phase transformations, in which they replace the energy expression in terms of polynomials, a stiff family of functions, with one in terms of more flexible functions, for instance certain splines. One of the arguments in favor of this more flexible choice is the inability of an energy proposed earlier by Ericksen and James to fit reasonably well all the elasticities of an InTl alloy, in particular the wide difference in the measured L ̂ 44 and L̂ 44 elasticities of the InTl martensite. While the proposal of Zimmer is theoretically very interesting and fit for numerical applications, and shows potential for modelling materials with complex internal structure, here I show that the pessimism about the standard Landau approach is indeed excessive as far as the weak points of the Ericksen–James energy are concerned. I propose a fourth–degree polynomial energy which extends the one of Ericksen and provides a fairly accurate fit of the equilibria as well as the elasticities for an In15.5 %Tl alloy and perhaps also for different compositions in the InTl family. The starting point is the version of Ericksen's theory [5] given in [12]. [ABSTRACT FROM AUTHOR]

Abstract: The phase diagram for the quasi-binary Tl2Se–SnSe2 system was constructed based on the results of studies by both thermal analysis and X-ray diffraction. The diagram was compared with two other diagrams for the same system published earlier by other authors. The study produced substantial evidence corroborating the formation of two new chemical compounds. [Copyright &y& Elsevier]

Abstract: The important features of nitrides materials include extreme hardness, high thermal conductivities, and make them as strategic material system for device applications at high pressure and temperature. The purpose of the present study is to predict novel ternary III–V alloys based on the TlN compound. We present and analyse first the important features of pure TlN before handling the complete contribution regarding the predictive alloy Ga1−x Tl x N. From the obtained results we notice the inverted band gap in TlN, which reflects a semi-metallic character and a strong charge transfer towards the nitrogen atom. For Ga1−x Tl x N alloys, the optical band gap bowing (i.e., the nonlinearity noticed in the variation of the alloy as a function of the amount of concentration x) is found to be strong and composition dependent following the same tendency of the other highly mismatched III–V alloys, where the composition induces disorder in bond lengths. [Copyright &y& Elsevier]

Abstract: The thermodynamic properties and phase diagrams of the Cd–Na and Cd–Tl binary systems have been optimized by the CALPHAD method. The liquid, hcp and bcc phases of the Cd–Tl binary system as well as the liquid phase of the Cd–Na binary system are treated with the substitutional solution model. The binary intermetallics, Cd11Na2 and Cd2Na, are considered to be stoichiometric. Experimental information available in the literature on phase equilibria, enthalpies of mixing, enthalpies of formation and activities is employed. Self-consistent thermodynamic parameters formulating the Gibbs free energies of various phases are obtained. The calculated phase diagrams and thermodynamic properties are in satisfactory agreement with those reported experimental data. [Copyright &y& Elsevier]

Abstract: TlBi(1−x)Sb x Te2 quaternary crystals that crystallize in a rhombohedral structure and according to their properties are classified between semimetals and narrow energy gap semiconductors, are studied. The study of their optical and electrical behavior reveal that they are quite sensitive to the Sb content x, and it is found that the substitution of Bi- with Sb-atoms in TlBiTe2 crystals leads initially to a decrease in the plasma frequency. However, for higher Sb contents, the plasma frequency increases. At room temperature, samples with x <0.8 are n-type semiconductors, becoming p-type ones for x >0.8. A model suggesting a suppression of the free electron concentration induced by the incorporation of Sb atoms into the crystal lattice of TlBiTe2 is used to explain this transition in the conductivity type. [Copyright &y& Elsevier]

The polytypes of monoclinic TlInS2 ( c ∼ 15, 60, 120 Å) and triclinic TlInS2 ( c ∼ 30 Å) were prepared. The positions of edge excitons and the band gaps were determined by the optical and photoelectric measurements. It was found that the maxima in the temperature dependences of dielectric constants of pure polytypes are situated at different temperatures. The photoconductivity spectra and the capacitive measurements showed that pure polytypes are unstable and transform with time into a mixture of the monoclinic polytypes of TlInS2. It is also established that all polytypes of monoclinic crystals tend to transform to the triclinic system. [ABSTRACT FROM AUTHOR]

The existence of two polytypes at room temperatures, C-TlInS2 and 2 C-TlInS2, with different monoclinic cell parameters, c and 2 c, has been revealed. Significant differences in crystal lattice dynamics of these polytypes have been found. In particular, two phase transitions (PTs) have been detected for the polytype C-TlInS2 as the temperature varies: a second-order PT from paraphase to incommensurate phase at T i = 215 K and a first-order ferroelectric PT accompanied by a quadrupling of the parameter c at T c = 197 K. No PT accompanied by an increase in unit cell parameter c has been found in the polytype 2 C-TlInS2, but a global temperature hysteresis characteristic of crystals with an incommensurately modulated structure has been detected at T = 180–230 K. [ABSTRACT FROM AUTHOR]

The existence of two polytypes at room temperatures, C-TlInS2 and 2 C-TlInS2, with different monoclinic cell parameters, c and 2 c, has been revealed. Significant differences in crystal lattice dynamics of these polytypes have been found. In particular, two phase transitions (PTs) have been detected for the polytype C-TlInS2 as the temperature varies: a second-order PT from paraphase to incommensurate phase at T i = 215 K and a first-order ferroelectric PT accompanied by a quadrupling of the parameter c at T c = 197 K. No PT accompanied by an increase in unit cell parameter c has been found in the polytype 2 C-TlInS2, but a global temperature hysteresis characteristic of crystals with an incommensurately modulated structure has been detected at T = 180–230 K. [ABSTRACT FROM AUTHOR]

The polytypes of monoclinic TlInS2 ( c ∼ 15, 60, 120 Å) and triclinic TlInS2 ( c ∼ 30 Å) were prepared. The positions of edge excitons and the band gaps were determined by the optical and photoelectric measurements. It was found that the maxima in the temperature dependences of dielectric constants of pure polytypes are situated at different temperatures. The photoconductivity spectra and the capacitive measurements showed that pure polytypes are unstable and transform with time into a mixture of the monoclinic polytypes of TlInS2. It is also established that all polytypes of monoclinic crystals tend to transform to the triclinic system. [ABSTRACT FROM AUTHOR]

Abstract: The surface phase transition (SPT) line has been calculated at the Ga-rich side of the binary Ga–Tl system. The liquid alloys at a given temperature can be divided into the following four different regions as a function of Tl-content of the alloy: (i) at very low Tl-content one bulk Ga-rich alloy is obtained not covered by any nano-layer, (ii) at a somewhat higher Tl-content one bulk Ga-rich liquid phase is obtained, covered by a Tl-rich nano-layer, (iii) at medium Tl-content two bulk liquids are obtained, (iv) at high Tl-content one Tl-rich liquid is obtained with no nano-layer on it. An improved version of the Ga–Tl phase diagram is offered, showing the equilibrium SPT line and the region of the Ga-rich bulk liquid, covered by a Tl-rich nano-layer. The presence of the latter changes some physical properties of the system. Particularly, the temperature coefficient of the surface tension changes from a low negative value to a high positive value when increasing the Tl-composition of the alloy and the SPT line is crossed. The position of the SPT line is essential to control Marangoni convection in liquid monotectic alloys. [Copyright &y& Elsevier]

Abstract: This paper describes the present status and prospects for further development of transparent conducting oxide materials for use as Indium-Tin-Oxide (ITO) substitutes in the thin-film transparent electrodes of liquid crystal displays (LCDs), currently the largest use of ITO, and, thus, of indium. The best substitute material for the ITO transparent electrodes used in LCDs is impurity-doped ZnO, e.g., Al- and Ga-doped ZnO (AZO and GZO). From resource and environmental points of view, AZO is the best candidate. The most important problems associated with substituting impurity-doped ZnO for the ITO used in LCDs have already been resolved in laboratory trials. Under the present circumstances, (rf and dc)-magnetron sputtering (rf+dc-MS) deposition, both with and without H2 gas introduction, has been found to be the best deposition method to prepare impurity-doped ZnO thin films for practical use; AZO thin films with a resistivity on the order of 10− 4 Ω cm were prepared on glass substrates with an approximately uniform resistivity spatial distribution and a thickness above 100 nm. In order to improve the resistivity stability, AZO and GZO thin films co-doped with another impurity have been newly developed. A 50 nm-thick V-co-doped AZO (AZO:V) thin film was stable enough to be acceptable for use in practical transparent electrode applications. However, it seems likely that obtaining a stability comparable to that of ITO using impurity-doped ZnO will be difficult for thin films with a thickness below approximately 30 nm. [Copyright &y& Elsevier]

Abstract: Tin-doped In2O3 (indium-tin-oxide) films were deposited on non-flat Si substrates using an original spray chemical vapor deposition (CVD) system. When the deposition temperature was 300–350 °C, ITO films covered all surfaces (top surface, side walls, and bottom; opening size was 1 μm) after being sprayed 50 times. The step coverage decreased as the number of spray increased because the opening size became smaller due to the layered ITO films, and it therefore became increasingly difficult to supply raw materials. The ITO films could not be deposited when the grooves narrowed to less than 0.18 μm. The step coverage of ITO films clearly increased, although the deposition rate decreased due to the decreasing deposition temperature. [Copyright &y& Elsevier]

Abstract: High power pulsed magnetron sputtering (HPPMS) has been used in order to study the deposition of transparent conducting oxides. We summarize the studies carried out on different materials (indium tin oxide-ITO and aluminium-doped zinc oxide-AZO) using rather different technological approaches, namely sputtering of ceramic targets and reactive sputtering. For the deposition of AZO reactive HPPMS for metallic targets has been used. A feedback control loop has been implemented in order to stabilize the discharge at any given setpoint on the hysteresis curve. The hysteresis was also found to have a rather untypical form. Reactive HPPMS was found to be a promising tool for obtaining high quality films of low total thickness. In the case of ITO deposition a ceramic target has been used. The process has been characterized in terms of its plasma emission and increasing indium ionization was found for higher peak power densities. The properties of the deposited films were compared to DC sputtered films. While for DC sputtering the choice of oxygen addition and shieldings is crucial for determining surface morphology and resistivity, in HPPMS sputtering peak power density has been found to be a good parameter for influencing the crystal structure. The morphologies obtained differ strongly from those seen in DC sputtering. At high power densities films with low surface roughness and excellent resistivity could be deposited without the use of shieldings. [Copyright &y& Elsevier]

Abstract: ITO and ZnO:Al films have been deposited by magnetron sputtering from ceramic and metallic targets at different substrate temperatures and with different plasma excitation modes: DC and RF (13.56 and 27.12 MHz). Temperature-dependent conductivity and Hall measurements (down to 50 K) were used to determine the carrier concentrations N D and the Hall mobilities μ. From the μ(N D) dependences, which were fitted by a carrier transport model taking into account ionized impurity and grain barrier scattering, the trap densities at the grain boundaries were estimated. ITO films show much lower trap densities down to N t ≈1.5·1012 cm−2, compared to N t values up to 3.1013 cm−2 for ZnO:Al films. The temperature-dependent mobilities were fitted by a phenomenological model with a T-independent term and a metal-like contribution or a thermally-activated part due to grain barrier-limited transport. Seebeck coefficient measurements as a function of the carrier concentration give hints to different transport mechanisms in ITO and ZnO. [Copyright &y& Elsevier]

Experimental studies of CsI(TI) crystals with different amounts of TI activator are presented. Properties such as non-proportionality, energy resolution and the number of photoelectrons per 1 MeV-γ were inspected at two different shaping time constants, i.e., 3 and 12 μs. A CsI(Tl) crystal was coupled to the XP5212 PMT with a photocathode blue sensitivity of 12.2 μA/ImF. Six CsI(TI) crystals of different sizes were tested. Among them, three samples were of known TI concentration, which amounted roughly 0.05, 0.1 and 0.25 mol%. The data analysis showed a much more proportional character of the crystal response, higher number of photoelectrons/MeV-γ, and consequently, a better overall energy resolution obtained for 12 μs time constant for all tested samples. The calculated intrinsic resolution improved for longer shaping time constants as well, indicating that, for CsI(TI) crystals, a more proportional response implies better intrinsic energy resolution of the host crystal. In contrast, the intrinsic resolution at the low energy region (below about 30 keV) deteriorated for the longer shaping time constant. An α/γ ratio was also measured for each tested CsI(TI) crystal in order to find any indication of an explanation of the intrinsic resolution deterioration for low energy photons at the 12 μs integration time. [ABSTRACT FROM AUTHOR]

Abstract: Photoluminescence (PL), photoluminescence excitation (PLE) and selective excitation (SE-PL) studies were performed in an attempt to identify the origin of the emission bands in a pseudomorphic In0.05Ga0.95N/GaN film. Besides the InGaN near-band-edge PL emission centred at 3.25 eV an additional blue band centred at 2.74 eV was observed. The lower energy PL peak is characterized by an energy separation between absorption and emission–the Stokes’ shift–(500 meV) much larger than expected. A systematic PLE and selective excitation analysis has shown that the PL peak at 2.74 eV is related to an absorption band observed below the InGaN band gap. We propose the blue emission and its related absorption band are associated to defect levels, which can be formed inside either the InGaN or GaN band gap. [Copyright &y& Elsevier]

Internal friction and dynamic shear modulus in an indium–21&ThickSpace;at.% thallium alloy were measured as functions of frequency and cooling rate using broadband viscoelastic spectroscopy during the martensitic transformation which occurs in this material occurs around 50°C. Microstructural evolution of martensitic bands was captured using time-lapse optical microscopy. The amplitude of damping peaks due to the temperature-induced transformation in the polycrystalline alloy was found to exceed those reported by others for single crystals of similar alloy compositions, in contrast to the usual reduction in damping in polycrystals. The high temperature portion of the damping peak occurs before martensitic bands are observed; therefore this portion cannot be due to interfacial motion. Constrained negative stiffness of the grains can account for this damping, as well as for amplification of internal friction peaks in these polycrystals and for sigmoid-shaped anomalies in the shear modulus at high cooling rates. Surface features associated with a previously unreported pre-martensitic phenomenon are seen at temperatures above martensite-start. [ABSTRACT FROM AUTHOR]

Describes the development of textured buffer layers that are compatible with thallium-based superconductor films on metallic substrates. Crucial properties involved in the development; Thallination process; Buffer layer materials investigated.

The band structures, absorption coefficients, and Auger recombination rates in narrow-gap alloys HgCdTe, InTIP, InTlAs, and InTlSb in the zinc blende structure, along with those of GaAs, are calculated using a hybrid pseudopotential and tight-binding method. The composition-dependent band gaps of the thallium-based alloys are reported along with those of several other semiconductor alloys. Within 50 meV from the absorption edge, the absorption coefficient of InxTl1−xP is found to have about the same magnitude as that of HgxCd1−xTe and GaAs, while that of InxTl1−xAs and InxTl1−xSb is much smaller. In agreement with previous theories, the calculated Auger lifetimes in Hg0.78Cd0.22Te with unit or k • p overlap agree very well with experiments. Among the thallium alloys studied, the Auger lifetimes are longest in In0.33Tl0.67P, but still shorter than those in Hg0.78Cd0.22Te by an order of magnitude. In addition, realistic overlaps produce lifetimes one to two orders of magnitude larger than those observed. [ABSTRACT FROM AUTHOR]

We proprose the ternary semiconducting Al1-xTlxN alloys as new material for optoelectronic applications. Ab initio calculations have been performed to study structural, electronic, and optical properties of the theoretically designed thallium-aluminum based nitride alloys. We found that the lattice constants vary linearly with thallium composition whereas the band gap and absorption edge span from ultraviolet to infrared energy region by increasing thallium content which make the predicted material interesting for infrared optical devices among other technological applications. [ABSTRACT FROM AUTHOR]

Examines the magnetic and transport properties of high-critical-current Tl[sub 2]Ba[sub 2]Ca[sub 2]Cu[sub 3]O[sub x] superconducting thin films. Fabrication of the films by single-target direct current sputtering ; Linear temperature dependence of the zero-field critical current at low temperature.

Several polythermal sections, the isothermal section at 300 K, and the projection of the liquidus surface of the Tl-TlI-Se system are constructed using DTA, XRD, and EMF methods. [ABSTRACT FROM AUTHOR]