Te Samples Research Articles

Interplay of boron localized states and electron transport in BxGa1-x As0.11 P0.89:Te

We study the magnetotransport properties of n-type BxGa1-x As0.11 P0.89:Te alloy samples with in magnetic fields up to 4 T between 10 and 280 K, some samples also under hydrostatic pressure up to 15 kbar. As a general trend the resistivity increases with increasing x, as both the carrier concentration and the mobility of electrons decrease. The free carrier concentration and mobility of the reference sample GaAs0.11 P0.89:Te is almost independent of the applied hydrostatic pressure, in particular, at higher temperatures whereas the B0.018Ga0.982As0.11P0.89:Te sample exhibits a different behavior. Its resistivity decreases due to a substantial increase of its free carrier concentration under pressure. This behavior is explained by the existence of a boron-related density of localized states in the vicinity of the conduction band edge of the alloy. The boron states act as electron traps as well as efficient scattering centers. Applying hydrostatic pressure shifts the energetic positions of conduction band edge at the X-point and of the boron states apart, reducing the impact of boron on the electronic transport properties of the alloy.

Enhanced thermoelectric performance of MnTe via Cu doping with optimized carrier concentration

Polycrystalline Mn1-xCuxTe (x = 0, 0.025, 0.05, 0.075) thermoelectric materials were prepared by a combined method of melt-quenching and hot press. The effect of Cu doping on the electrical resistivity, band gap, the Seebeck coefficient and thermal conductivity was investigated. The power factors of the Cu-doped samples increase greatly due to the decrease of electrical resistivity and the higher Seebeck coefficient in high temperatures. In addition, the thermal conductivities of the Cu-doped samples also reduce due to the extra phonon scattering from the point defects introduced by Cu doping. As a result, the thermoelectric performance of MnTe is greatly enhanced, and a maximum ZT value of ∼0.55 in the Mn0.925Cu0.075Te sample at 773 K is achieved, which is 35% greater than that of the pristine MnTe sample.

PENGARUH MODAL INTELEKTUAL TERHADAP KINERJA PERUSAHAAN PADA PERUSAHAAN PERBANKAN YANG TERDAFTAR DI BURSA EFEK INDONESIA

The purpose of this study is to test empirically the relationship between intellectual capital and frm performance. Intellectual capital is measured using the method Pulic namely value added intellectual coefcient (value added intellectual coefcient-VAICTM) as a measure of the efciency of venture capital and intellectual capital. The company’s performance is measured using four indicators, namely ROA, ATO, ROE, and MB. Te sample used by 27 companies listed banking sector in Indonesia Stock Exchange f rom 2007 until 2012. Data analysis too lused to test the hypothesis is Partial least square (PLS). Hypothesis test results show evidence that intellectual capital and signifcant positive efect on company performance and future performance of the company. For the rate of growth in intellectual capital (ROGIC) did not signifcantly afect the future performance of the company.Keywords: intellectual capital, company performance, Partial Least Square (PLS)

ANALISIS PENGGUNAAN SISTEM INFORMASI AKUNTANSI PADA USAHA KECIL DAN MENENGAH DI YOGYAKARTA

This study aimed to analyze the practice of the use of Accounting Information Systems (AIS) on Small and Medium Enterprises (SMEs) in Yogyakarta. In this study, analysis of the use of the SIA will be seen from the aspect of business, scale of business, company age, education owner or manager of the company, lead times, and accounting training followed by the owner or manager of the company. This research is descriptive. This research was conducted by asking questions to the respondent by distributing questionnaires. Te sampling method used is purposive sampling. Questionnaires were distributed to 100 owners or managers of SMEs in Yogyakarta, but there are six questionnaires that are not in accordance with the criteria of the sample, thus the amount of the fnal sample to 94.The results showed that the majority of SMEs in Yogyakarta have been using AIS in its operational activities. Manufacturing companies, medium-sized companies, the company that is older than 20 years, the owners or managers of companies whose educational background diploma, the owner or manager of the company that led the company for more than 5 years, the owner or manager of a company that did not get accounting training the majority of use accounting information more intensively.Keywords: Accounting Information Systems, the use of accounting information, management of operational activities, small and medium enterprises.

High Thermoelectric Performance and Enhanced Mechanical Stability of p-type Ge1–xSbxTe

High thermoelectric figure of merit, zT, of ∼1.85 at 725 K along with significant cyclable temperature stability was achieved in Pb-free p-type Ge1–xSbxTe samples through simultaneous enhancement in Seebeck coefficient and reduction of thermal conductivity. Sb doping in GeTe decreases the carrier concentration due to the donor dopant nature of Sb and enhances the valence band degeneracy by increasing the cubic nature of the sample, which collectively boost Seebeck coefficient in the temperature range of 300–773 K. Significant thermal conductivity reduction was achieved due to collective phonon scattering from various meso-structured domain variants, twin and inversion boundaries, nanostructured defect layers, and solid solution point defects. The high performance Ge0.9Sb0.1Te sample shows mechanical stability (Vickers microhardness) of ∼206 Hv, which is significantly higher compared to other popular thermoelectric materials such as Bi2Te3, PbTe, PbSe, Cu2Se, and TAGS.

Galvanomagnetic effects in tellurium whiskers

Galvanomagnetic effects on Te samples were studied. The measurements were made in the broad range of temperatures (1.5 K ≤ T ≤ 80 K) and the values of the magnetic field induction. Shubnikov–de‐Haas oscillations (SH) were detected in strong magnetic fields (ωcτ ≫ 1, where ωc is the cyclotrone frequency); as well as anomalous temperature dependence of the Hall potential in classically weak (ωcτ ≪ 1) magnetic fields. It was found out that the revealed SH oscillations are due to the Landau quantizations of the energy spectrum of three‐dimensional (3D) charge carriers (holes) in the bulk samples under study. In the area of weak magnetic fields (ωcτ ≪ 1), the effect of anomalous magnetoresistance was found, which was due to the weak localization of 3D holes in the samples . The theory of the Hall effect for holes in weak magnetic fields (B < 0.2 Т) was developed. It is based on the solution of kinetic Boltzmann equation with the specific type of the collision integral; taking into account the carriers energy spectrum in tellurium. It was shown that the peculiarities of the Hall effect temperature dependence; which were found experimentally in weak magnetic fields; can be qualitatively explained if we bear in mind the complex structure of tellurium valence band.

Thermoelectric properties of c-GeSb0.75Te0.5 to h-GeSbTe0.5 thin films through annealing treatment effects

Germanium–Antimony–Tellurium (Ge–Sb–Te) thin films were deposited on silicon wafers with 1-μm silicon dioxide (SiO2/Si) by pulsed dc magnetron sputtering from a 99.99% GeSbTe target of 1:1:1 ratio at ambient temperature. The samples were annealed at 573, 623, 673, and 723 K for 3600 s in a vacuum state. The effects of the annealing treatment on phase identification, atomic composition, morphology and film thickness, carrier concentration, mobility, and Seebeck coefficient of the Ge–Sb–Te samples have been investigated by grazing-incidence X-ray diffraction, auger electron spectroscopy, field-emission scanning electron microscopy, Hall-effect measurements, and steady state method, respectively. The results demonstrated that the as-deposited Ge–Sb–Te sample was amorphous. Atomic composition of as-deposited and annealed films at 573 K and 623 K were GeSb0.75Te0.5 while annealed films at 673 K and 723 K were GeSbTe0.5 due to Sb-rich GeSb0.75Te0.5. The samples annealed at 573 K and 623 K showed the crystal phases of cubic structure (c-GeSb0.75Te0.5) into hexagonal structure (h-GeSbTe0.5) after annealing at 673 K and 723 K. The study demonstrated the insulating condition from the as-deposited GeSbTe film, and the changes towards the thermoelectric properties from the annealing treatments. The GeSbTe films annealed at 673 K yielded excellent thermoelectric properties with the electrical resistivity, Seebeck coefficient, and power factor at approximately 1.45 × 10−5 Ωm, 71.07 μV K−1, and 3.48 × 10−4 W m−1 K−2, respectively.

Laser desorption ionization time-of-flight mass spectrometry of Ge-As-Te chalcogenides.

Ge(x)As(y)Te(z) glasses have a broad window of optical transparency and high refractive index which make them promising for applications in the infrared region. The aim of this work is to reveal structural motifs which could be present during the fabrication of Ge-As-Te thin films by plasma deposition techniques; such knowledge is important for the optimization of thin film growth. Mass spectra were acquired using a laser desorption ionization time-of-flight (LDI-TOF) mass spectrometer equipped with a nitrogen laser (337 nm) coupled with a quadrupole ion trap, and recorded in positive and negative ion reflectron modes. XRD, SEM (EDX) and Raman spectroscopy were also used for the characterization of Ge-As-Te bulk or powdered samples. Bulk Ge(x)As(y)Te(z) samples (x = 10-20%, y = 20-60%, z = 30-70%) were synthesized. LDI-MS of Ge-As-Te powders provided evidence for the formation of both positively and negatively charged clusters, whose stoichiometry was determined as Te(n)(+/-) (n = 1-4), Te(5)(+), binary AsTe(n)(+/-) (n = 1-3), GeTe(n)(+/-) (n = 1-3), As(2)Te(+/-), As(2)Te(3)(+), As(3)Te(+), AsTe(4) (+), Ge(2)H(6) (+/-), ternary GeAsTe(+), GeAsTe(2)(+/-), GeAsH5 (+), GeAsH(6)(+), GeAsH(12)(+), and tertiary GeAsTeH(5)(-), GeAsTeH(8)(-), GeAsTe(2)H(3) (+/-). The local structure of Gex Asy Tez materials is at least partly different from that of species identified in plasma by mass spectrometry, as deduced from Raman scattering spectroscopy analysis. However, LDI-TOFMS was found to be a suitable technique for the partial structure characterization of Ge-As-Te bulk samples and especially for the identification of the structural motifs present in the plasma during the preparation of the corresponding thin films.

Reduced lattice thermal conductivity in nanograined Na-doped PbTe alloys by ball milling and semisolid powder processing

Achieving grains of less than 100nm in bulk PbTe-based alloys is challenging, and yet can improve the thermoelectric performance of the alloys by reducing lattice thermal conductivity κlat. In this study, nanostructured Na0.02Pb0.98Te samples with grain sizes of 20–100nm were fabricated by high energy ball milling and semisolid powder processing. Microstructures were investigated by scanning and transmission electron microscopies. The κlat values of the samples showed significant reductions compared with those of reference samples with grains larger than 100nm, mainly due to stronger phonon scattering at grain boundaries. The κlat reached a minimum value of 0.74Wm−1K−1 at 623K.

Structuring effect of heteroepitaxial CdHgTe/CdZnTe systems under irradiation with silver ions

The characteristics of a damaged layer of p-CdxHg1 − xTe/CdZnTe (x ∼ 0.223) heterostructures after implantation by 100-keV silver ions with the implantation dose Q = 3.0 × 1013 cm−2 have been obtained using X-ray diffraction, atomic force microscopy, and electron microscopy. It has been found that, as a result of the ion implantation and subsequent annealing (75°C), a uniform array of nanostructures is formed on the surface of Hg(Cd)Te/Zn(Cd)Te samples. The X-ray diffraction patterns of the structurized Hg(Cd)Te/Zn(Cd)Te sample indicate the formation of polycrystalline Hg(Cd)Te phases of cubic structure with a composition x ∼ 0.20 and also oxide Ag2O in the subsurface (<100 nm) region of the host material. The observed effects of transformation of the defect-impurity system and structuring of the surface of the heteroepitaxial film of the low-energy-gap semiconductor have been explained using a deformation model.

English

Blood cells extraction and detection is very much important for all human beings, because there are WBCs, RBCs, Platelets in our blood, White blood cell count gives the vital information that help diagnosis many of the patient’s sickness. This work presents a new adaptive approach of extracting and detecting the WBCs in blood sample microscopic images. In the research work the author used two different approaches one is k-means clustering algorithm and second is Hough transform. Author also used to study the different parameters like radius of the cells, calculate the time for getting the output from te sample input image.

Physical mechanisms of terahertz pulse emission from photoexcited surfaces of tellurium crystals

We report on terahertz (THz) emission from tellurium crystal surfaces excited by femtosecond optical pulses. Measurements were performed on three differently cut Te samples and with different wavelength optical excitation pulses. THz pulse amplitude dependences on the azimuthal angle measured at various excitation wavelengths have evidenced that three different mechanisms are responsible for THz generation in tellurium: second order nonlinear optical rectification effect, dominating at lower excitation photon energies, as well as transverse and ordinary photo-Dember effects, which emerge at energies larger than 0.9 eV. The shapes of the azimuthal angle dependences were also explained by theoretical model.

COMPRESSIVE AND TENSILE STRENGTH OF CONCRETE USING LATERITIC SAND AND LIME STONE FILLER AS FINE AGGREGATE

This paper is part of a study investigating the str uctural characteristics of concrete using various c ombinations of lateritic sand and lime stone filler as complete replacement for criver sand fine aggregate. The lime sto ne filler obtained from limestone quarries. The concrete are made using var ying contents of lateritic and lime stone filler as fine aggregate. The quantity of laterite is varied from 0% to 100% against lime stone filler at intervals of 25%. Samples of concre te (eg.cubes and cylinders) are made in three different grades, namely: M15, M2 0 and M25. It was found that 0.55 water/cement rati o produced higher compressive strengths, tensile strength and better workability for M20 mix, proportion. Specifically c ompressive and tensile strength ranged from 21.06 -35.2 N/mm 2 and 10.06 -15.5 N/mm 2 for the mixes considered. These results compare fa vourably with those of conventional concrete. The concrete was fo und to be suitable for use as structural members fo r buildings and related structures, where laterite content did not exceed 5 0%.

Methods for the determination of stable Te isotopes of minerals in the system Au–Ag–Te by MC-ICP-MS

The measurement of stable isotopes in ore- and ore-related minerals can provide insight into the geochemistry and formation of metal-bearing ore systems. Currently, there are few high-precision studies of the natural variability of stable tellurium isotopes, most of which are focused on meteorites and sulfides and are related to cosmogenesis; there are no modern studies on the variability of tellurium isotopes within native tellurium and tellurides from ore-forming systems. Tellurium is an element of interest due to its common association with gold in geologic systems, as well as its rarity in the Earth's crust and increasing industrial demand for applications such as photovoltaics. This study presents a method by which tellurium can be sampled from Au–Ag tellurides and native tellurium, isolated by ion exchange chromatography, and analyzed for isotopic composition by multi collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS). Using a micromill, a sufficient mass of telluride or native Te sample can be extracted from coexisting ore and gangue minerals from ∼100 μm wide by ∼50 μm deep drilled holes. Acid digestion of micromilled samples and subsequent ion exchange chromatography isolated Te from matrix metals. The chromatography procedure has Te yields of 96% and produces no net fractionation of Te isotopes. MC-ICP-MS analyses were performed using two techniques, both of which employed the doping of samples using Cd to correct for instrumental mass bias. The first method was the introduction of 100 ppb Te-bearing solutions (with 100 ppb Cd) using a desolvating nebulizer (Aridus II). The second method involved solution nebulization of 2 ppm solutions of Te (with 1 ppm Cd) into the plasma of the MC-ICP-MS. Although the wet and dry methods produce statistically identical delta values, precision is increased using the wet method. The average uncertainty (two standard deviations of the mean) using the Aridus II is ±0.20‰ for 130/125Te (dry method), whereas that for the wet method is ±0.08‰. Repeated analyses of the Te standard over a period of ∼15 months by solution nebulization yielded an external precision of ±0.10‰ for 130/125Te. Natural, hypogene tellurides (calaverite, hessite, krennerite, and sylvanite) and native tellurium samples (n = 32) have a range of 1.64‰ in the isotope composition 130/125Te, demonstrating resolvable, disparate isotope ratios between samples from different areas and between samples from the same locality (e.g., Cripple Creek, Colorado). Fractionation of Te isotopes was caused by mass-dependent geological processes.

Segregation Study of Some Impurities in Three Purification Process of CdTe Ingots

Abstract Several attempts were made during the last 3 decades to improve the quality of CdTe in order to enhance its efficiency as material for nuclear and photovoltaic devices. These attempts considered the high values of impurity segregation coefficients and the contamination problems due to handling at high temperature. In this study, we prepared three high purity CdTe single crystals with high resistivity. The three starting Te samples were purified through three purification processes: horizontal zone refining, vacuum distillation, and by combining both processes. Purities were characterized, by determining the concentration of 22 impurities by Atomic Absorption (AASGF), for the three kinds of tellurium ingots and the corresponding elaborated CdTe materials. A series of four effective segregation coefficients for metallic impurities: Ag, Al, Cu, and Fe were found in CdTe. Their high values confirmed the difficulty to remove them by the purification processes using the segregation phenomenon. In addition, the low concentration values of impurities in CdTe samples (≥ 6N purity) make from our CdTe high quality electronic grade materials.

A vaporization study of the Ru–Te binary system by Knudsen effusion mass spectrometry

Vaporization studies on some Ru–Te samples with initial compositions 40.0 and 50.5at.% Te, corresponding to the two-phase field (Ru+RuTe2) and of initial compositions 69.5 and 71.5at.% Te, corresponding to the two-phase field (RuTe2+Te) were conducted by Knudsen effusion mass spectrometry. The vaporization was found to be one of incongruent in nature with the vapor phase consisting only of the component tellurium. The partial pressures of Te2(g) and Te(g) were measured over (Ru+RuTe2) in the temperature range of (860–1030)K and the p–T relations were deduced as: Log [p(Te2)/Pa]=[−(14,335±148)/(T/K)]+(14.416±0.154) and Log [p(Te)/Pa]=[−(13,838±218)/(T/K)]+(12.480±0.226). The relative mole fraction of Te(g) was<0.05. From the partial pressures, the thermodynamic data for the vaporization reactions RuTe2(s)=Ru(s)+2/i Tei(g) where i=2 and 1 were deduced and so also were for the formation of RuTe2(s):ΔrHmo(298.15K)/(kJmol-1)=284.3±16.4(i=2)and537.7±24.7(i=1);ΔrSmo(298.15K)/(Jmol-1K-1)=200.2±10.4(i=2)and155.0±4.3(i=1);ΔfHmo(RuTe2,s,298.15K)/(kJmol-1)=-(121.1±16.4);ΔfSmo(RuTe2,s,298.15K)/(Jmol-1K-1)=-(39.8±10.4).The p(Te) and p(Te2) values over this two-phase field are consistent with those previously measured by us over other binary metal-tellurium systems with regard to equilibrium constant for the dissociation reaction Te2(g)=2 Te(g). The preferential vaporization of tellurium was utilized to make the sample traverse from the (RuTe2+Te) two-phase field to (Ru+RuTe2) two-phase field via the single phase region of RuTe2 and the evolution of Te2(g) monitored all through. That there is a composition range of existence for the RuTe2 phase and that the Ru-rich boundary composition is close to stoichiometric value became confirmed from these measurements.

A Slightly Oxidizing Etchant for Polishing of CdTe and CdZnTe Surfaces

New iodine-evolving etching solutions were developed for surface treatment of CdTe and CdZnTe crystals. The nature of the chemical dissolution of CdTe samples with (100), (110), and (111) orientations, and also of (211) Cd0.96Zn0.04Te samples, in KIO3-KI-lactic acid solution was studied. It was established that this dissolution is diffusion controlled. Surface roughness measurements revealed highly polishing properties of the etchant. A study of the chemical composition and structure of the (211)B Cd0.96Zn0.04Te surfaces etched under different conditions was carried out. The thickness of the Te oxide layer was evaluated in the course of heating in vacuum. KIO3-KI-lactic acid treatment appears to be preferable in terms of elimination of Te oxides from the surface as compared with standard Br2-methanol solution. The etching compositions were shown to be useful for chemical polishing of CdTe-based surfaces.

Synthesis, characterization and performance of Cd1−xInxTe compound for solar cell applications

Cd1−xInxTe (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples have been synthesized chemically using wet chemical method from precursor compounds, CdSO4, InCl3, and TeCl4. The hydroxide form of the solution mixture was obtained by using ammonia solution and the pH of the mixture was adjusted to 9. A suitable amount of NaBH4 solution was added to reduce the hydroxide phase to the metalloid alloy. The crystal structure has been studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The 300°C annealed samples revealed a cubic crystal structure. The morphology of the prepared samples is very fine and the average diameter is between 1 and 2.5μm. The optical properties were determined using UV–vis–NIR spectrophotometer and band gap energy of 1.37eV for Cd0.6In0.4Te was obtained. The best photovoltaic conversion efficiency of 1.89% was obtained for the Cd0.6In0.4Te sample with a short circuit current density (Jsc) of 15.3mAcm−2, an open circuit voltage (Voc) of 0.668V, and a filling factor (FF) of 69.31%.

THERMAL AND MINERALOGICAL STUDIES OF MOROCCAN RIF BITUMINOUS ROCKS

A study was conducted on four bituminous rock samples from Tangier, Tetouan, Bab Taza and Arba Ayach deposits (samples TA, TE, BT, AA, respectively) in the Rif region of northern Morocco. The study was carried out using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XFR), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and scanning electron microscopy with energy dispersive spectrum analysis (SEM-EDX). The results obtained by these methods showed that the organic part of TA, TE, BT and AA samples was 5.59 wt%, 6.73 wt%, 4.77 wt% and 7.53 wt%, respectively. Therefore these bituminous rocks can be considered a perspective energy resource. The dominant mineral phase in all samples is quartz (70.04-84.46 wt%). Clay minerals (illite, chlorite) and other mineral components are present in different low-weight proportions.

Antilocalization effect in HgCdTe film

The antilocalization effect is observed by magnetotransport measurement at low temperature on a Hg0.77Cd0.23 Te sample prepared by liquid epitaxy technique,which suggests a strong spin-orbit interaction within this system.The phase coherence time and spin-orbit scattering time of electrons are extracted by fitting the experiment data with the Hikami-Larkin-Nagaoka(HLN) theory plus the Drude conductance model.According to the temperature dependence of phase coherence time,we also find that the Nyquist mechanism dominates the dephasing process.