scholarly journals Lead Telluride Doped with Au as a Very Promising Material for Thermoelectric Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Pantelija M. Nikolic ◽  
Konstantinos M. Paraskevopoulos ◽  
Triantafyllia T. Zorba ◽  
Zorka Z. Vasiljevic ◽  
Eleni Pavlidou ◽  
...  
Keyword(s):  
Electronic Transport ◽  
Room Temperature ◽  
Plasma Frequency ◽  
Lead Telluride ◽  
Far Infrared ◽  
Optical Parameters ◽  
High Quality ◽  
Free Carriers ◽  
Reflectivity Spectra

PbTe single crystals doped with monovalent Au or Cu were grown using the Bridgman method. Far infrared reflectivity spectra were measured at room temperature for all samples and plasma minima were registered. These experimental spectra were numerically analyzed and optical parameters were calculated. All the samples of PbTe doped with Au or Cu were of the “n” type. The properties of these compositions were analyzed and compared with PbTe containing other dopants. The samples of PbTe doped with only 3.3 at% Au were the best among the PbTe + Au samples having the lowest plasma frequency and the highest mobility of free carriers-electrons, while PbTe doped with Cu was the opposite. Samples with the lowest Cu concentration of 0.23 at% Cu had the best properties. Thermal diffusivity and electronic transport properties of the same PbTe doped samples were also investigated using a photoacoustic (PA) method with the transmission detection configuration. The results obtained with the far infrared and photoacoustic characterization of PbTe doped samples were compared and discussed. Both methods confirmed that when PbTe was doped with 3.3 at% Au, thermoelectric and electrical properties of this doped semiconductor were both significantly improved, so Au as a dopant in PbTe could be used as a new high quality thermoelectric material.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXIV Syntheses, Spectroscopy and Structures of Some 1 : 4 Adducts of Copper(I) and Silver(I) Perchlorates with Triphenylarsine and Triphenylstibine

1997 ◽  
Vol 50 (6) ◽  
pp. 539 ◽  
Author(s):  
Graham A. Bowmaker ◽  
Effendy ◽  
Robert D. Hart ◽  
John D. Kildea ◽  
Brian W. Skelton ◽  
...  
Keyword(s):  
Room Temperature ◽  
Far Infrared ◽  
Lewis Base ◽  
X Ray ◽  
Cation Disorder ◽  
Structure Determinations ◽  
Consistent Picture ◽  
Far Infrared Spectra

Syntheses and room-temperature single crystal X-ray structure determinations are recorded for adducts [M(EPh3)4] (ClO4), M = Cu, E = As (1), Sb (2); M = Ag, E = As (3), Sb (4), enabling comparison with analogous, previously studied MP4 and MN4 environments. The four complexes so characterized all crystallize in the familiar rhombohedral R-3 array (a ≈ 14·4, c ≈ 52 Å, hexagonal setting) with the metal and chlorine atoms located on crystallographic threefold axes. In these arrays Cu–E (axial, off axis) are 2·493(2), 2·533(1) for (1), and 2·572(1), 2·577(1) Å for (2), the disparity in the two independent M-E distances being diminished relative to those of previously studied phosphorus analogues, perhaps in consequence of increasing E size. In (3) and (4), some cation disorder is evident in respect of the ligand pnictide atom (E); for the major components Ag-E are 2·652(3), 2·680(2) in (3); 2·732(2), 2·7295(8) Å in (4). Problems associated in defining the metal atom environment geometries in the latter are, nevertheless, more satisfactorily overcome in two further determinations of nitrate salts: [Ag(SbPh3)4] (NO3) (5) is of the rhombohedral family with no cation core disorder, Ag–E (axial, off axis) being 2·720(4), 2·725(2) Å, while the structural characterization of a 1 : 4 triphenylarsine adduct of silver nitrate is recorded as its tetraethanol solvate, namely [Ag(AsPh3)4] (NO3).~ 4C2H5OH(6), monoclinic, C2/c, a 18·373(4), b 20·786(5), c 21·070(8) Å, β 108·18(3)°, Z = 4 f.u. The silver atom of the [Ag(AsPh3)4]+cation unusually lies on a crystallographic 2 (rather than a 3 ) axis of the incipiently23 (T) array, with Ag-As 2·649(2), 2·650(2) Å and As-Ag-As ranging from 108·22(4) to 111·41(6)°. The structure determination of a chloroform solvate of (2), denoted (2a), of low precision, is noted, together with the structure of an interesting artefact, isomorphous with the rhombohedral oxoanion array, modelled as [Ag(PPh3)4]2 (SiF6).py (7). Bands in the far-infrared spectra of [M(AsPh3)4] (ClO4) are assigned to v(MAs) vibrations at 119 (M = Cu) and 103 cm¯1 (M = Ag); this produces a more consistent picture of the variation in the wavenumbers of the v(ME) modes in [M(EPh3)4]+ compounds than was available previously.

Infrared reflectance spectroscopy of MgAl2O4 nanoparticles substituted by K+ ions

2018 ◽  
Vol 32 (06) ◽  
pp. 1850067 ◽  
Author(s):  
Javed Ahmad ◽  
M. Qadeer Awan ◽  
Roomana Yasmin ◽  
Maria Sabir ◽  
Shafiq Anwar ◽  
...  
Keyword(s):  
Room Temperature ◽  
Longitudinal Optical ◽  
Reflectance Spectroscopy ◽  
Optical Parameters ◽  
Frequency Range ◽  
Phonon Modes ◽  
Metallic Behavior ◽  
Lorentz Oscillator ◽  
Reflectivity Spectra ◽  
Ftir Spectrometer

The infrared reflectivity spectra for potassium-doped polycrystalline magnesium aluminates Mg[Formula: see text]K[Formula: see text]Al2O4 (x=0, 0.25, 0.50, 0.75, 1) are measured in the frequency range between 10–15, 500 cm[Formula: see text] using FTIR spectrometer at room-temperature. Four optical phonon modes are observed in measured spectra, which are fitted by Lorentz oscillator model for semiconducting behavior and Lorentz–Drude model for metallic behavior. Moreover, optical parameters are also determined for these modes which may attribute to spinel structure for samples Mg[Formula: see text]K[Formula: see text]Al2O4, their reflectivity spectra shows a typical semiconducting nature. To study ionicity and effect of polarization, Born and Szigeti effective charges are calculated from longitudinal optical and transverse optical (LO–TO) splitting of modes for all samples. Optical bandgap has been estimated through optical conductivity ([Formula: see text]([Formula: see text])) and found to be x dependent.

Nonmonotonous Behavior of Temperature-Dependence of Plasma Frequency and Effect of a Local Instability of the PbTe:In,Ga Lattice

1997 ◽  
Vol 484 ◽  
Author(s):  
A. I. Belogorokihov ◽  
L. I. Belogorokhova ◽  
D. R. Khokhlov
Keyword(s):  
Temperature Dependence ◽  
Plasma Frequency ◽  
Lattice Structure ◽  
Lead Telluride ◽  
Far Infrared ◽  
Infrared Region ◽  
Anomalous Behavior ◽  
Local Instability ◽  
Impurity Centers ◽  
First Time

AbstractThe optical spectra of PbTe:In,Ga samples were studied in the Far Infrared region at temperatures T=11 K–3 50K. Anomalous behavior of the temperature dependence of the plasma frequency at 65K–80K was observed for the first time. This is explained by means of a model of localized changes in the lead telluride lattice structure near impurity centers.

Synthesis and characterization of single-crystal indium nitride nanowires

2004 ◽  
Vol 19 (2) ◽  
pp. 423-426 ◽  
Author(s):  
Tao Tang ◽  
Song Han ◽  
Wu Jin ◽  
Xiaolei Liu ◽  
Chao Li ◽  
...  
Keyword(s):  
Electronic Transport ◽  
Room Temperature ◽  
Thermal Emission ◽  
Indium Nitride ◽  
Chemical Vapor ◽  
Gold Clusters ◽  
Vapor Generation ◽  
Vapor Deposition Technique ◽  
Single Nanowires

InN nanowires were synthesized and characterized using a variety of techniques. A two-zone chemical vapor deposition technique was used to operate the vapor generation and the nanowire growth at differential temperatures, leading to high-quality single-crystalline nanowires and growth rates as high as 4–10 μm/h. Precise diameter control was achieved by using monodispersed gold clusters as the catalyst. Photoluminescence and Raman studies have been carried out for the InN nanowires at room temperature. Devices consisting of single nanowires have been fabricated to explore their electronic transport properties. The temperature dependence of the conductance revealed thermal emission as the dominating transport mechanism.

Nanoindentation as a Tool for Formation of Thin Film-Based Barrier Structures

2005 ◽  
Vol 864 ◽  
Author(s):  
H. Khlyap ◽  
P. Sydorchuk
Keyword(s):  
Room Temperature ◽  
Far Infrared ◽  
Point Of View ◽  
Surface Barrier ◽  
Defect Engineering ◽  
High Quality ◽  
Laser Technology ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Selection Of

AbstractA2B6 semiconductors and their solid solutions (ZnSe, ZnTe, CdTe, ZnCdHgTe) are matter of choice for near- and far-infrared optoelectronics. The importance of maximally reduced degree of defectness for these materials is not subjected to discussion. However, preparation of high quality barrier structures based on these compounds by means of MBE, laser technology or liquid phase technique is not always successful due to lattice parameters mismatch. At the same time, good selection of a proper buffer layer may also pose some unavoidable problems. From this point of view the nanoindentation as a tool of defect engineering can be effective for fabrication of surface barrier structures. The first experimental results and numerical simulation of experimental data obtained under investigation of nanoindentation effect on electric characteristics (in particular, current – voltage (I-V) and capacitance – voltage (C-V)) of ZnCdHgTe thin films and ZnCdHgTe/Cd(Zn)Te heterostructures at the room temperature are presented.

Solution Growth and Characterization of Icosahedral Boron Arsenide (B12As2)

2011 ◽  
Vol 1307 ◽  
Author(s):  
C.E. Whiteley ◽  
Y. Zhang ◽  
A. Mayo ◽  
J.H. Edgar ◽  
Y. Gong ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solution Growth ◽  
High Quality ◽  
Burgers Vector ◽  
X Ray ◽  
Dislocation Densities ◽  
Boron Arsenide ◽  
Viable Method ◽  
Molten Nickel

ABSTRACTThe crystallographic properties of bulk icosahedral boron arsenide (B12As2) crystals grown by precipitation from molten nickel solutions were characterized. Large crystals (5-8 mm) were produced by dissolving the boron in nickel at 1150°C for 48-72 hours, reacting with arsenic vapor, and slowly cooling to room temperature. The crystals varied in color from black and opaque to clear and transparent. Raman spectroscopy, x-ray topography (XRT), and defect selective etching revealed that the B12As2 single crystals were high quality with low dislocation densities. Furthermore, XRT results suggest that the major face of the plate-like crystals was (111) type, while (100), (010) and (001) type facets were also observed optically. The predominant defect in these crystals was edge character growth dislocations with a <001> Burgers vector, and <-110> line direction. In short, XRT characterization shows that solution growth is a viable method for producing good quality B12As2 crystals.

The Growth and Characterization of Large Diameter Silicon Carbide Substrates

2000 ◽  
Vol 640 ◽  
Author(s):  
A. Gupta ◽  
M. Yoganathan ◽  
J. Burton ◽  
N. Byrd ◽  
A. Dimondi ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Raman Spectroscopy ◽  
Room Temperature ◽  
New Technologies ◽  
Large Diameter ◽  
Wide Band ◽  
Wide Band Gap ◽  
High Quality ◽  
Industrial Environment

ABSTRACTAffordable, high quality SiC wafers are very desirable for a variety of new technologies including GaN based lighting, RF, and high-power electronics based on wide band gap materials. At Litton Airtron we have a major effort in the growth and characterization of SiC. We will present data on 35, 50 and 75-mm diameter crystals. We are growing both n-type, semiinsulating 4H, 6H, and 15R material. A variety of characterization techniques are being used at Litton Airtron to determine wafer quality. These include Raman microscopy, digital wafer photography, and crossed polarizer images. Raman spectroscopy is an excellent probe of polytype and carrier concentration for n-type materials; in addition it can be done at room temperature and is sufficiently fast that it can be used in an industrial environment. The use of digital photography allows for the collection of images that can be quantitatively analyzed and archived.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXI Synthesis, Spectroscopy and Structural Systematics of Some 1 : 2 Binuclear Adducts of Silver(I) Compounds with Triphenylarsine, [(Ph3As)2Ag(µ-X)2Ag(AsPh3)2], X = Cl, Br, I, SCN

1997 ◽  
Vol 50 (6) ◽  
pp. 627 ◽  
Author(s):  
Graham A. Bowmaker ◽  
Effendy ◽  
John D. Kildea ◽  
Eban N. de Silva ◽  
Allan H. White
Keyword(s):  
Infrared Spectra ◽  
Structural Characterization ◽  
Room Temperature ◽  
Far Infrared ◽  
Lewis Base ◽  
X Ray ◽  
C 23 ◽  
Pseudo Halides ◽  
Far Infrared Spectra

The syntheses and room-temperature single-crystal X-ray structural characterization of binuclear 1 : 2 adducts formed between silver(I) (pseudo-)halides, AgX, and triphenylarsine, AsPh3, for X = Cl, Br, I, SCN (1)–(4), are described. The chloride (1), obtained from 2-methylpyridine, is triclinic, P-1, a 10·410(2), b 12·716(2), c 14·196(6) Å, α 113·38(2), β 109·41(2), γ 75·08(1)°, Z = 1 (dimer); conventional R on F was 0·037 for No 3979 independent ‘observed’ (I > 3σ(I)) reflections. The bromide (2a), obtained from 2,6-dimethylpyridine, and iodide (3), obtained from a mixture of AgI/saturated KI in MeOH solutions, are isomorphous, monoclinic, P 21/c a≈ 24·2, b ≈ 13·9, c ≈ 20·2 Å, β ≈ 109·5°, Z = 4 dimers; R was 0·046 and 0·044 for No 5670 and 6039 respectively. The thiocyanate (4) has a similar cell, a 24·12(1), b 12·558(8), c 23·244(4) Å, β 110·11(3)°, Z = 4 dimers, R being 0·044 for No 7956; one of the thiocyanate ligands (which bridge in Ag-SCN-Ag mode) is disordered. A second polymorph of the bromide (2b) (from a mixture of AgBr/saturated KBr in H2O) is also monoclinic, P 21/c, a 14·121(8), b 25·577(3), c 21·968(2) Å, β 125·54(3)°, Z = 4 dimers (R was 0·047 for No 5715). Ag–As range between 2·568(1) and 2·633(1) Å throughout the series; in the isomorphous bromide and iodide, values increase slightly: 2·578(1)–2·611(1), cf. 2·601(2)-2·633(1) Å respectively. Ag–X are 2·568(2)-2·670(2) (Cl); 2·688(2)–2·715(2) (Br); 2·828(2)–2·856(1) Å (I); Ag-S, N for the ordered SCN group are 2·646(3), 2·255(6) Å. A redetermination of improved precision (R 0·035, No 6030) is reported for the triphenylphosphine/thiocyanate analogue. The far-infrared spectra of [(Ph3As)2Ag(µ-X)2Ag (AsPh3)2] show v(AgX) bands at 185, 145 (X = Cl), 145, 130, 106 (X = Br) and 121 cm-1 (X = I). The splittings and band widths reflect a decrease in the degree of distortion of the Ag(µ-X)2Ag units from a symmetrically bridged structure from X = Cl to I.

Far infrared reflectivity spectra of lead-telluride doped with Ytterbium

2008 ◽  
Vol 466 (1-2) ◽  
pp. 319-322 ◽  
Author(s):  
P.M. Nikolic ◽  
D. Lukovic ◽  
S.S. Vujatovic ◽  
K.M. Paraskevopoulos ◽  
M.V. Nikolic ◽  
...  
Keyword(s):  
Lead Telluride ◽  
Far Infrared ◽  
Infrared Reflectivity ◽  
Reflectivity Spectra

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXIII Synthesis, Spectroscopy and Structural Systematics of New 1 : 1 'Cubane' Tetramers of Copper(I) and Silver(I) Halides with Triphenylarsine

1997 ◽  
Vol 50 (6) ◽  
pp. 653 ◽  
Author(s):  
Graham A. Bowmaker ◽  
Effendy ◽  
Robert D. Hart ◽  
John D. Kildea ◽  
Allan H. White
Keyword(s):  
Room Temperature ◽  
Far Infrared ◽  
Lewis Base ◽  
Potassium Iodide Solution ◽  
X Ray ◽  
Iodide Solution ◽  
Benzene Solvate ◽  
The Common ◽  
Far Infrared Spectra

Syntheses and room-temperature single-crystal X-ray structural characterization of a number of 1 : 1 ‘cube tetramer’ adducts of copper(I) and silver(I) halides, MX, with triphenylarsine, AsPh3, are recorded, being [XM(AsPh3)]4. The CuBr adduct, obtained unsolvated from toluene, orthorhombic Pbcn, a 17·844(5), b 20·778(8), c 18·430(4) Å, Z = 4 tetramers, conventional R on |F| 0·058 for No 1309 independent ‘observed’ reflctions (I > 3σ(I)), is isomorphous with previously recorded [ClAg(PPh3)]4, the tetramer having crystallographically imposed 2 symmetry. The CuI adduct, previously recorded as a monobenzene solvate, has been isolated unsolvated from toluene, monoclinic, P 21/n, a 19·70(5), b 27·110(7), c 13·59(2) Å, β 98·84(9)°, Z = 4 tetramers, R 0·087 for No 4359, isomorphous with previously recorded [ICu(PPh3)]4, as a 6½ benzene solvate, triclinic, P-1 a 26·688(2), b 15·180(7), c 13·090(1) Å, α 85·41(2), β 87·580(7), γ 77·63(2)°, Z = 2 tetramers, R 0·049 for No 11485, and as a chloroform disolvate, triclinic, P-1 a 22·584(9), b 13·979(2), c 13·892(2) Å, α 68 ·99(2), β 77·31(3), γ 75·65(3)°, Z = 2, R 0·041 for No 8701. An unsolvated AgI complex, monoclinic, P 21/c, a 25·26(1), b 12·506(5), c 25·228(9) Å, β 113·54(4)°, Z = 4 tetramers, R 0·054 for No 5520, isomorphous with previously recorded [IAg(PPh3)]4 (denoted ‘α’), was obtained from methanol/saturated potassium iodide solution, while a second ‘β’-form obtained from 2,4,6-trimethylpyridine, rhombohedral R3c, a 17·048(7) Å, α 61·15(5)°, Z = 2 tetramers, R 0·037 for No 1622, is isomorphous with previously recorded [BrAg(PPh3)]4, for which a redetermination is described (R 0·039 for No 1289); the latter has also been obtained in the common orthorhombic Pbcnarray: a 18·10(1), b 2·08(1), c 18·39(1) Å, Z = 4, R 0·041 for No 2877. A new ‘step’ form of [IAg(PPh3)]4, monoclinic, C 2/c, a 26·14(2), b 16·340(9), c 18·64(2) Å, β 114·04(8)°, R 0·058 for No 2107, obtained from acetonitrile and isomorphous with [BrCu(PPh3)]4 (step), is also recorded. In the far-infrared spectra of [(Ph3As)4Cu4X4] bands which have been assigned to vibrations of the Cu4X4 core are: 166, 150, 135, 114 (X = Br); 136, 85 cm-1 (X = I; 2CHCl3 solvate). The 166, 150, 135 cm-1 bands in the bromide are only partially resolved. These, and the 136 cm-1 band in the iodide are assigned to the T2 v(CuX) mode of the Cu4X4 core; the bands at 114 and 85 cm-1 are assigned to the next highest frequency T2 mode of the cluster. The splitting of the highest frequency T2 band for the bromide is consistent with the greater degree of distortion of the Cu4X4core from ideal Td symmetry in this complex relative to the iodide.

Sign in / Sign up

Export Citation Format

Share Document