- Investigation on self-aligned HgTe nano-crystals induced by controlled precipitation in PbTe-HgTe quasi-binary compound semiconductor alloys
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The present paper reports the results of the controlled precipitation for the HgTe nano-crystals in the PbTe semiconductor matrix and demonstrates its effectiveness in producing well-organized and crystallographically aligned semiconductor nano-crystals. Following the same procedure used in metallic alloys, the semiconductor alloys are treated at 600°C for 48 h, quenched and aged up to 400 h at 300°C and 400°C to induce homogeneous nucleation and growth of HgTe precipitates. Examination of the resulting precipitates using transmission electron microscopy (TEM) reveals that the coherent HgTe precipitates form as thin disks along the {1 0 0} habit planes of PbTe matrix. It is also found that the precipitate undergoes a gradual shape change without any noticeable coarsening, from a disk to a cube, as the aging time increases. The microstructure after full aging is found to contain almost equal sized HgTe cubes, roughly 7 nm, that maintain coherency with {1 0 0} planes of the matrix. These results combined with the extreme dimension of the precipitates and the simplicity of the formation process leads to a belief that controlled precipitation can be an effective method in preparing a desirable quantum-dot microstructure.
- Lee, Manjong,Kim, Choong-Un
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- Ordering phenomena and demixing in the quasiternary system Ga2Te3/Hg3Te3/In2Te3
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The phase diagram of the quasiternary system Ga2Te3/Hg3Te3/In2Te3 for the temperature range 650a three-phase region, there occurs also a miscibility gap within an ordered region.
- von Wensierski,Bolwin,Zeppenfeld,Leute
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- Preparation of Cu(2-x)Te and HgTe by using microwave heating
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A new method for the preparation of nanophased tellurides is described. It employs microwave heating for the synthesis of Cu(2-x) Te and HgTe. The copper telluride prepared by this method was a complex of Cu(2-x)Te and ethylenediamine, which decomposes into pure Cu(2-x)Te following annealing at 280°C. A mechanism for the micowave-assisted formation of the tellurides is proposed. (C) 2000 Academic Press.
- Palchik,Kerner,Zhu,Gedanken
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- PYROELECTRICITY OF Cd-DOPED TELLURIDE THIN FILM.
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The crystalline structure, electrical conductivity and pyroelectricity of freshly prepared Hg//0//. //7Cd//0//. //3Te thin film have been investigated in detail. In the initial heating stages, the pyroelectric current slowly falls, followed by abrupt decreases corresponding to the breaks in the curves at temperatures depending on the poling temperature, as a general trend in common. Thus 70 degree is the best poling temperature for attainment of a high generated pyroelectric current, holding up to relatively high working temperatures for the investigated HgCdTe films in the electronic and engineering industries. 13 Refs.
- Tawfik, A.,El Mekawey, F. M.
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- Convenient, room-temperature, amine-assisted routes to metal sulfides, selenides and tellurides
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The reaction of elemental powders of Ag, Pb and Hg with S, Se or Te in n-butylamine for 12-72 h produced crystalline metal chalcogenides ME (M = Pb or Hg; E = S, Se or Te) and Ag2E in good yield (>90%). The reactions of Cu with Se or Te in n-bu
- Dusastre, Vincent,Omar, Bashe,Parkin, Ivan P.,Shaw, Graham A.
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- Solution-chemical syntheses of nanostructure HgTe via a simple hydrothermal process
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HgTe rod-shape composed of crystalline particles has been prepared by a hydrothermal method, and characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transition electron microscopy (TEM). The effects of capping agents, reductants, reaction temperatures, and reaction times on crystal structures and shapes of HgTe have been investigated. The results showed that the CTAB as capping agent plays a crucial role in the hydrothermal process. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods.
- Salavati-Niasari, Masoud,Bazarganipour, Mehdi,Davar, Fatemeh
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- A new synthetic route for the preparation of metal tellurides
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A new method of synthesis for the formation of metal tellurides of the type MTe (M = Cd, Hg) is reported. The compounds were prepared by the reaction of cadmium carbonate (or mercury oxide, respectively) with tellurium and bis(diphenylphosphino)amine in toluene at 160 C. The products were characterized by powder XRD and EDX analyses. The whole chemical process is discussed.
- Kubát, Václav,Losos, Zdeněk,Trávní?ek, Zdeněk,Novosad, Josef
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- Molar heat capacities of CdTe, HgTe and CdTe-HgTe alloys in the solid state
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Using a differential scanning calorimeter, the molar heat capacities of the two components HgTe and CdTe and of ten solid alloys of the CdTe-HgTe system were measured at constant pressure between 300 K and 523 K. Irregular variations of the Cp = f(T) curves of CdTe-HgTe alloys suggest the existence of a solid-state miscibility gap in this system. The limit of the (solid ? solid(1) + solid(2)) miscibility gap and coordinates of the critical temperature (xCdTe = 0.55, T = 455 K) are proposed. From Cp data obtained in a single-phase solid region, the excess molar heat capacities (ΔCp = Cp(exp) - Cp(calc)) at 500 K were deduced: the maximum negative excess Cp is located at xCdTe = 0.5.
- Gambino,Vassiliev,Bros
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- Thermodynamic investigations of HgTe
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The free energy of formation of HgTe has been determined by an electrochemical technique using an SbCl3-KCl + 5wt.%Hg2Cl2 molten electrolyte. In the temperature range 340-410 K, the ΔGf° vs. T relationship (ΔGs
- Nasar,Shamsuddin
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- MOCVD of p-CdxHg1-xTe/GaAs heteroepitaxial structures
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Metalorganic chemical vapor deposition from Cd and Te alkyl compounds and Hg vapor is used to grow p-type CdxHg1-xTe epitaxial layers on semi-insulating GaAs(111)B substrates by the interdiffused multilayer process (alternating CdTe and HgTe layers) at a substrate temperature of 350°C, followed by postgrowth annealing. Layers are obtained with x = 0.2-0.4, 77-K carrier concentrations in the range (1-5) × 1016 cm-3, and 77-K carrier mobilities from 200 to 400 cm2/(V s). The rocking curves of the epilayers have a full width at half maximum in the range 2-4 min of arc.
- Moiseev,Kotkov,Dorofeev,Grishnova
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- Room-temperature conversion route to nanocrystalline mercury chalcogenides HgE (E = S,Se,Te)
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A convenient, simple route has been employed to synthesize the nanocrystalline HgE (E = S,Se,Te) in ethylenediamine at room temperature. Mercury oxide was used as mercury source and sulfur, selenium, tellerium, respectively, as chalcogenide sources. The obtained products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. XRD patterns show that the products were hexagonal (wurtzite structure) HgS, cubic (zincblende structure) HgSe and HgTe. We also find that the ethylenediamine plays a crucial role in the conversion process.
- Li, Yadong,Ding, Yi,Liao, Hongwei,Qian, Yitai
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- LOW TEMPERATURE SYNTHESIS OF Hg1 - xCdxTe, O less than equivalent to x less than equivalent to 1.
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Solid solutions of Hg//1// minus //xCd//xTe with O less than equivalent to x less than equivalent to 1. 0 were prepared at low temperatures, where the Hg pressure is about 1 atm. For the composition x less than 0. 7, complete reaction was observed within
- Ben-Dor,Yellin,Shaham
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- Contribution to the Study of the Silver-Mercury-Thallium-Tellurium Quaternary System: Study of AgTlTe-HgTe.
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The AgTlTe-HgTe system has been studied by DTA and X-ray diffraction techniques. The diagram is characterized by an intermediate phase Ag//3HgTl//3Te//4 (or Ag//0//. //2//7Hg//0//. //0//9Tl//0//. //2//7Te//0//. //3//6) with 25 mol% HgTe and a high-temperature phase for T greater than 597 K in the range from 30 to 60 mol% HgTe. Electric measurements have been carried out for Ag//3HgTl//3Te//4.
- Gardes,Ayral-Marin,Brun,Tedenac
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- Electronic structure of HgTe nanocrystals: An observation of p-d weakening
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Photoemission studies to identify the electronic structure of the HgTe nanocrystals revealed a new phenomenon of p-d weakening, as a consequence of size quantization effect associated with the mean crystalline size, 5.35 ± 0.83 nm. The weakening of the p-d hybridization by a factor of 0.33, to that of the bulk HgTe suggests the valence band maxima and core level shifts toward higher binding energy. The widening of the band gap due to size quantization is confirmed from optical absorption and photoluminescence measurements. The upward and downward shift of the conduction band minima and the valence band maxima with respect to the bulk value of HgTe are found to be 1.6 eV and 0.54 eV respectively.
- Rath,Sahu
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- Ordering phenomena and demixing in the quasiternary system HgTe/CdTe/In2Te3
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The phase diagram of the quasiternary system Cd(3-3k(2)-3k(1))Hg3k(1)In2k(2)Te3 for the temperature range 600≤T/K≤900 was investigated by X-ray diffraction, DTA measurements and electron microprobe analysis. It
- Weitze,Schmidtke,Leute
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- Colloidal HgTe nanocrystals with widely tunable narrow band gap energies: From telecommunications to molecular vibrations
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A convenient, aqueous-based synthesis of stable HgTe nanocrystals with widely size-tunable room temperature emission between wavelengths of 1.2 to 3.7 μm is demonstrated. By the choice of the thiols, applied as stabilizers, we optimized the growth dynamics, the luminescence quantum yields (up to 40%), and a ligand-exchange procedure, required to transfer the nanocrystals from water to nonpolar organic solvents. The latter is greatly improved and facilitated by the use of mercaptoethylamine as initial stabilizer. The possibility to tune the HgTe nanocrystal sizes from 3 to 12 nm and to control their surface functionalities (hydrophobic and hydrophilic) makes them very promising for the development of infrared optical devices, emitting in the wavelength region between the telecommunications and the molecular vibrations. Copyright
- Kovalenko, Maksym V.,Kaufmann, Erich,Pachinger, Dietmar,Roither, Juergen,Huber, Martin,Stangl, Julian,Hesser, Guenter,Schaeffler, Friedrich,Heiss, Wolfgang
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- Rb2Hg3Te4: A New Layered Compound Synthesized from Solvothermal Reactions
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A layered mercury telluride, Rb2Hg3Te4, was discovered during an exploration of hydro(solvo)thermal synthesis of tellurides at temperatures somewhat above the boiling point of ethylenediamine. Crystals of Rb2Hg3Te4 were grown from solvothermal reactions using ethylenediamine as a solvent. Single crystal X-ray diffraction analysis shows that this compound belongs to the orthorhombic system, space group Pbcn (No. 60) with lattice parameters a = 12.177(2) A?, b = 7.245(2) A?, c = 14.545(2) A?, and Z = 4. The structure contains two-dimensional layers of ∞2[Hg3Te42-] which are separated by the Rb+ counterions. The interlayer Te-Te distances imply weak van der Waals interactions. Rb2Hg3Te4 is the first two-dimensional mercury telluride prepared by an unconventional low-temperature technique.
- Li, Jing,Chen, Zhen,Lam, Kin-Chung,Mulley, Suzanne,Proserpio, Davide M.
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- Synthesis, characterization, and solution behavior of mercury(II) chloride complexes with phosphine tellurides
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The reaction of mercury(II) chloride with neutral phosphine telluride ligands (R3PTe) produced new mercury(II) complexes, HgCl2(R3PTe)2 [R = Me2N (1), Et2N (2), C4H8N
- Mallek,Sanhoury,Bahri,Khaddar,Ben Dhia
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- 3-(Diphenylchalcogenophosphoryl)propionic acids as precursors for metal selenides and tellurides
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New reaction systems leading to cadmium, mercury and lead selenides and tellurides are reported. The chalcogenides were prepared by a simple, direct reaction between chalcogen, metal oxide or carbonate, and 3-(diphenylphosphino)propionic acid. The synthesis of 3-(diphenyltellurophosphoryl)propionic acid (1) is described and X-ray structures of 3-(diphenylphosphino)propionic acid (2) and its P[dbnd]E derivatives are presented, where E?=?O (3), S (4) and Se (5).
- Kubát, Václav,Babiak, Michal,Trávní?ek, Zdeněk,Novosad, Josef
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- Bis(3-methyl-2-pyridyl)ditelluride and pyridyl tellurolate complexes of zinc, cadmium, mercury: Synthesis, characterization and their conversion to metal telluride nanoparticles
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Treatment of an acetonitrile solution of metal chloride with bis(3-methyl-2-pyridyl)ditelluride, [Te2(pyMe)2], in the same solvent yielded complexes of composition [MCl2{Te 2(pyMe)2}] (M = Zn or Cd) w
- Kedarnath,Jain, Vimal K.,Wadawale, Amey,Dey, Gautam K.
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p. 8378 - 8385
(2010/03/04)
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- Diiodobis(diphenyltelluride)mercury(II), [(Ph2Te)2HgI2]
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Diiodobis(diphenyltelluride)mercury(II), [(Ph2Te)2HgI2], is formed during the reaction of [(PhTe)2Hg] with HgI2 in refluxing THF. The same product can be obtained from a pressure reaction between PhTeI3 and elemental mercury. The mercury atom is co-ordinated in a distorted tetrahedral environment with I-Hg-I angles of 117°. Long range I...Te contacts of about 3.8 A link the [(Ph2Te)2HgI2] units to infinite chains along the b axis of the unit cell.
- Lang, Ernesto Schulz,Gatto, Claudia C.,Abram, Ulrich
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p. 335 - 336
(2008/10/08)
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- Liquid ammonia mediated metathesis: Synthesis of binary metal chalcogenides and pnictides
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Addition of stoichiometric amounts of low valent metal halides to liquid ammonia solutions of disodium chalcogenide (Na2E; E = S, Se, Te) afforded a range of both crystalline (PbE (E = S, Se, Te), TIE (E = S, Se), Tl5Te3, Ag2E (E = S, Se, Te)) and X-ray amorphous (MS (M = Ni, Cu, Zn, Cd, Hg), M2E3 (M = Ga, In; E = S, Se, Te), HgE (E = Se, Te), CuE (E = S, Se, Te), Cu2S) metal chalcogenides in good yield (95%). Reactions between metal halides and sodium pnictides (Na3Pn; Pn = As, Sb) in liquid ammonia also afforded X-ray amorphous material (M3Pn2, M = Zn, Cd; MPn, M = Fe, Co, Ni) in good yield (95%). Isolation of the metal chalcogenides and pnictides was achieved through washing with CS2 and distilled water. All reactions were complete within 36 h. Products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), electron probe analysis, FR-IR spectroscopy, Raman spectroscopy, microanalysis, and band gap measurements. Annealing amorphous material at 250-300 °C for 48 h induced sufficient crystallinity for analysis by X-ray powder diffraction.
- Shaw,Parkin
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p. 6940 - 6947
(2008/10/08)
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- Electrochemical reactions of Te(IV) and Hg(II) on carbon glass electrode in sulfate solutions
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The electrochemical reduction of Te(IV) and oxidation of the reduction products as influenced by Hg(II) in acidic solutions were studied by the potentiodynamic procedure. The wave of tellurium(IV) reduction to tellurium(0) (E1/2-0.32 V) and the maximal current of tellurium(0) reduction to Te2- (Emax -0.66 V vs. silver chloride electrode) were determined. In the presence of mercury the potential maximum shifts toward negative values by 0.22 V, which corresponds to the free energy of formation of HgTe (42.8 kJ mol-1). At positive potential the wave of HgTe oxidation (Emax 0.900 ± 0.003 V) was found.
- Dergacheva,Statsyuk,Fogel'
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p. 663 - 666
(2007/10/03)
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- Temperature dependence of the molar volume of molten mercury telluride and its description based on the two-structure model and the theory of associative equilibria
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New experimental data on the temperature dependence of the density and the molar volume of mercury telluride in the neighborhood of the crystal-melt phase transition point obtained by the method of penetrating γ-radiation are presented. It is shown that mercury telluride melts like water with compaction. Melting-induced volume jump values are discussed in terms of the Clausius-Clapeyron equation. It is shown that the temperature of fusion of mercury telluride should decrease as pressure increases. Heating the melt causes an anomalous increase in melt density. The observed temperature dependence of the molar volume of the liquid phase is analyzed in terms of the two-structure model and the theory of associative equilibria. The latter theory provides a good description of the temperature dependence of the molar volume based on the reasonable assumption of the coexistence in equiatomic melts of associates HgTe and more complex Hg2Te3 species. Calculations of the temperature dependence of the molar volume of mercury telluride in the liquid phase based on the two-structure model and the theory of associative equilibria give virtually coinciding results. This leads us to suggest that the disintegration of the clusters of the low-temperature (looser) structural component occurs as a result of thermal dissociation of the HgTe and Hg2Te3 associates present in melts.
- Glazov,Pavlova
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p. 158 - 163
(2007/10/03)
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- Convenient, room-temperature liquid ammonia routes to metal chalcogenides
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Reaction of sulfur, selenium or tellurium with elemental metals in liquid ammonia at room temperature in a pressure vessel produced metal chalcogenides ME (M = Ca, Sr, Ba, Eu, Yb, Ni, Zn, Cd, Hg, Sn or Pb; E = S, Se or Te), Ag2E, solid solutions of mixed-metal chalcogenides MxM′yEz (x + y = 1, z = 1 or 2), and metal-mixed chalcogenides MSxSey. Products showed a range of crystallite sizes from 700 A for PbSe and Ag2S to essentially amorphous (ZnS). Heating at 250-300°C under vacuum for 2 h induced crystallinity in the amorphous powders. The pre- and post-heated metal chalcogenides were analysed by X-ray powder diffraction, Fourier-transform IR, Raman microscopy, scanning electron microscopy-energy dispersive analysis of X-rays, electron microprobe, X-ray photoelectron spectroscopy, elemental analysis and magnetic susceptibility studies.
- Henshaw, Geoff,Parkin, Ivan P.,Shaw, Graham A.
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p. 231 - 236
(2007/10/03)
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- Interdiffusion in the Quasibinary Systems Cd3Te3/Ga2Te3 and Hg3Te3/Ga2Te3
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The quasibinary systems Cd3Te3/Ga2Te3 (I) and Hg3Te3/Ga2Te3 (II) form regions of extended solid solution.The interdiffusion of the cationic components in these regions is coupled with a flux of so-called structural vacancies.Peculiarities in the composition and temperature dependence of the interdiffusion coefficient, measured by an electron microprobe, are due to the effect of the thermodynamic factor.The calculation of the thermodynamic factor is based on a model of tetrahedral clusters.Special features of the phase diagrams of systems I and II are used to estimate the cluster energies.By use of these cluster energies the free excess enthalpy of the solid solution is calculated, and therefrom the thermodynamic factor can be derived.The course of the interdiffusion coefficients is caused by totally different influencies: in system I by a trend towards spinodal demixing, in system II by a trend towards ordering. Key Words: Clusters / Diffusion / Solid Solutions / Thermodynamics / Vacances
- Leute, Volkmar,Zeppenfeld, Astrid
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p. 233 - 241
(2007/10/02)
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- Application of phosphine tellurides to the preparation of group II-VI (2-16) semiconductor materials
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In order to find low-temperature routes to metal tellurides, we have investigated some of the reactions of phosphine tellurides. Via the phosphine telluride, tellurium is chemically transported by PMe3 under very mild conditions (T ≈ 150°C). Triethylphosphine telluride reacts with Hg at room temperature and with HgR2 (R = Et, Ph) at 115°C, in each case giving HgTe as the sole solid-state product. We studied the reaction with HgPh2 in greater detail, showing that Ph2Te and Ph2Te2 are the major organic products.
- Steigerwald,Sprinkle
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p. 245 - 246
(2008/10/08)
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- The Influence of a Miscibility Gap on the Reaction Behaviour of the Quasiternary System HgkCd(1-k)TelSe(1-l)
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Assuming a regular behaviour of the quasiternary alloy HGkCd(1-k)TelSe(1-l) we determined the mean molar free enthalpy, the coexistence curve and the spinodal curve.From the concentration profiles taken by an electron microprobe, we calculated the reaction paths for reaction couples of CdTe and HgSe for several reaction times and annealing temperatures.The occurrence of phase separation, precipitations and regions of uphill diffusion is discussed with regard to the influence of the miscibility gap on these phenomena.
- Leute, V.,Schmidtke, H. M.,Stratmann, W.
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p. 732 - 738
(2007/10/02)
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