bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature-Dependent XAFS Study on AgBr1-xIx Solid Solution
Authors: Ayato Hiroshi , Oda Shohei , Satow Yoshinori , Asakura Kiyotaka , Kuroda Haruo
Published: March 2014

Local structures of rock salt type AgBr1-x
I
x
solid solutions with x varying from 0.07 to 0.4, substances interesting from both viewpoints of crystal structure and excellent properties as a photographic material, have been investigated by EXAFS analysis of three sets of spectra, i.e., I K-edge, Br K-edge and Ag K edge, at various temperature from 10K to room temperature. The Br-Ag and I-Ag interatomic distances in the solid solution were different from each other and deviated from the average Ag-(Br,I), or virtual crystal, distance determined from X-ray diffraction at any temperature. The iodide content x dependence of I-Ag and Br-Ag interatomic distances changed with temperature. At low temperature the I-Ag and Br-Ag distances increased with increasing the iodide content, whereas at room temperature they did not exhibit significant change with composition. This suggested that the bonding nature of the AgBr1-x
I
x
solid solution is rather ionic at low temperature, while it is rather covalent at room temperature.
X-ray Absorption Fine Structure Studies on an Amorphous LaNi5.0 Film Prepared by Reactive Sputtering
Authors: Sakaguchi Hiroki , Suenobu Tomoyoshi , Tsujimoto Tetsuji , Moriuchi Kiyoaki , Kanai Hiroyoshi , Yoshida Satohiro , Adachi Gin-ya
Published: March 2014

The local structure of amorphous LaNi5.0 films prepared by reactive sputtering was investigated using XAFS and was compared with that by conventional sputtering. The interatomic distances and coordination numbers of both films coincided. The structural fluctuation was, however, found to be smaller for the reactive sputtered film than for the conventional sputtered film, because small Debye-Waller factors were obtained for the reactive sputtered film.
EXAFS Studies on the Local Structure of Amorphous Gd67Ni33
Authors: Nakai Ikuo , Maeda Hironobu
Published: March 2014

We describe results of the extended X-ray absorption fine structure (EXAFS) measurement about the Gd LIII edge on the local structure of amorphous Gd67Ni33. The analysis based on the subshell model gives that there exist two different interatomic distances between Gd and Ni, that is, 2.82 Å and 3.41 Å and one Gd-Gd interatomic distance of 3.67 Å. A Gd atom has 12.1 neighboring atoms which consist of 4.0 Ni atoms and 8.1 Gd neighbors.
EXAFS Measurements for Liquid Ge–Se Mixtures at High Temperatures and Pressures
Authors: Tamura Kozaburo , Hosokawa Shinya , Sakaguchi Yoshifumi , Inui Masanori , Endo Hirohisa
Published: March 2014

We have measured the EXAFS spectra of liquid Ge-Se mixtures around Ge and Se K-edges with Ge concentration of 8, 16 and 24 at.% at high temperatures and pressures up to 1400°C and 120 bar. From the detailed analysis of the EXAFS functions, we have obtained the results that there exist the covalently bonded four-fold coordinated structure around Ge atoms near the melting temperature in these mixtures, and the local atomic arrangements around Ge atoms is substantially changed when the SC-M transition occurs at higher temperatures above 1000°C.
Liquid-Glass Transition of RbNO3–Cd(NO3)2
Authors: Kawakita Yukinobu , Nagaya Kiyonobu , Yao Makoto , Endo Hirohisa
Published: March 2014

EXAFS measurements have been carried out for supercooled liquid and glassy CdRb(NO3)3 on the Kedges of both Cd and Rb by utilizing the synchrotron radiation. The radial distribution function around a Cd cation shows the broad peaks corresponding to an oxygen atom at 2.3Å and to a nitrogen atom at 3.8Å. The first peak of radial distribution function around a Rb atom is found to be at 2.7Å, which gives a relative distance between Rb and neighboring oxygen. When the supercooled liquid is transformed to a glassy state, the number of the nearest neighboring atoms around a Rb cation substantially increases in contrast to that around a Cd cation.
Evolution under Pressure of the Local Structure around Zinc and Mercury Atoms in ZnxHg1-xTe Solid Solutions
Authors: San-Miguel Alfonso , Polian Alain , Itie Jean-Paul , Marbeuf Alain
Published: March 2014

The high pressure evolution of the Zn-Te and Hg-Te bonds in the Zn1-xHgxTe pseudobinary solid solutions have been studied by x-ray absorption spectroscopy at the Zn K-edge and at the Hg LIII-edge for different compositions. The evolution of the first-neighbors distances by EXAFS analysis showed that the compressibility of the HgTe bond depends on the composition of the alloy. The zincblende phase destabilizes progressively at higher pressures by addition of ZnTe.
XAFS Study of Some Titanium Silicon and Germanium Compounds
Authors: Aldrich D. B. , Nemanich R. J. , Sayers D. E.
Published: March 2014

It has been shown that, across the full range of Si-Ge alloy compositions, C54 Ti(SiyGe1-y)2 will form from the reaction of Ti with SixGe1-x. An increase in the silicon fraction (i.e., y>x)was seen with the formation of Titanium Germanosilicide which may be due, in part, to the relative diffusion rates of Si and Ge in Ti. In C54 Ti(SiyGe1-y)2 the Si and Ge atoms occupy sites equivalent to the Si in C54 TiSi2. Within error, these atoms form shells about the Ti atoms, with Si and Ge occupancies indicative of the net Si and Ge atomic percents. The radial distances of the shells vary linearly, within error, between those of C54 TiSi2 and C54 TiGe2. The ability to vary the shell distances (and thus vary the lattice constants) of C54 Ti(SiyGe1-y)2 by varying Si and Ge content will prove useful in applications where lattice matching and epitaxy are of importance.
The Valence of Samarium in the Mixed-Valence Transition in SmSe
Authors: Bauchspiess K. R. , Crozier E. Daryl , Ingalls R.
Published: March 2014

The microscopic nature of the mixed-valence transition is of fundamental interest. We have used L-edge absorption spectroscopy to measure the valence of SmSe versus pressure at 77K and at 300K. With pressure SmSe undergoes a continuous valence transition as the Sm valence fluctuates between 2+ and 3+. We find that the valence varies with pressure as ((P-Pc)/Pc)α where the critical pressure is Pc=31.6 kbar. The exponent α was found to have the value 0.44 which is less than the value 1/2 expected for mean field theories.
XAFS Study on Reduction Process of Pauli-Paramagnetic LaNiO3 to Antiferromagnetic La2Ni2O5
Authors: Moriga Toshihiro , Kikkawa Shinichi , Takahashi Masao , Kanamaru Fumikazu , Nakabayashi Ichiro
Published: March 2014

Structural variation in a H2 reduction process of Pauli-paramagnetic LaNiO3 to antiferromagnetic La2Ni2O5 was investigated by means of XAFS spectroscopy. XANES spectra of LaNiO3-x (0≤x≤0.5) indicate that not the pyramidal coordination but the square-planar one is mainly formed even in an early step on the reduction. The Ni-O distance gradually decreased with an increase of the reducing durations, although the ionic radius of Ni ion should expand with the reduction. This phenomenon may be related to the lattice distortion of the octahedral NiO6 and planar NiO4 with cooperative Jahn-Teller ions of d
7-Ni3+ in the low spin state and d
9-Ni+, lying in the La2Ni2O5.
EXAFS Study of Nano-Phase Silver Particles
Authors: Itoh Masayuki , Tohno Susumu , Adachi Motoaki , Yamamoto Takao , Tsukui Shigeki
Published: March 2014

The structure of nano-phase silver particles was investigated by fluorescence EXAFS over several sizes of particles. The particle concentrates (>1021part./m3) were prepared using the aerosol process associated with surfactant coating to maintain the isolation of each particle. The EXAFS of the particles showed a good signal-to-noise ratio even in the particles less than 3 nm in diameter. The nearest neighbor distances of silver atom in the particles and foil were 0.289 (±0.002) nm for all the cases, and no distinct shrinkage of the atomic distance was observed for the silver particles in the size range of this work.
EXAFS Study of Chalcogen Microclusters
Authors: Endo H. , Maruyama K. , Tsuzuki T. , Yao M.
Published: March 2014

EXAFS measurements have been carried out on Se K-edge and Te K-edge for Se8-x
Te
x
and Se8-x
S
x
microclusters with 8 chalcogen atoms. The clusters with various compositions were isolated in a synthetic 4A zeolite which has 11Å-diameter cage units. The data analysis led us to believe that the clusters form 8-membered rings in the cage. In Se8-x
Te
x
microclusters, Se–Se bonds and Te–Te bonds are shorter than those in the crystalline state. It is found that Se–Te unlike-pairs are preferred over Se–Se and Te–Te like pairs. On the other hand, in Se8-x
S
x
microclusters, Se–Se and S–S like-pairs are found to be preferred over Se–S unlike-pairs.
X-ray Absorption Near Edge Structure of Single-Crystal Sapphire Using Synchrotron Radiation: The Interatomic-Distance Correlation
Authors: Chen J. M. , Rosenberg R. A. , Simons J. K. , Tan K. H.
Published: March 2014

The high-resolution Al L-edge X-ray absorption near edge structure (XANES) from a single-crystal sapphire sample has been recorded using the total-electron yield (TEY), X-ray fluorescence yield (XFY), and recombination luminescence excitation spectrum (RLES) utilizing synchrotron radiation. There is a very clear splitting of the Al L2 and L3 components (78.38 eV and 78.80 eV) in those spectra. To our knowledge, this is the first report on the Al L23 doublet splitting of single-crystal sapphire obtained from the total-electron yield measurement. All the spectra show similar structure, while the main feature of the RLES is an anticorrelated behavior relative to the TEY and XFY. The edge structures up to 11 eV from the L23 absorption edge are interpreted as due to transition of electron to empty levels of Al ion according to molecular-orbital calculations on the [AlO6]-9 molecules as determined by Balzarotti et al. The post-edge features between 11-60 eV above the Al L23 absorption edge were found to correlate very well with the interatomic distances from the absorbing atom to a neighboring atom as predicted by multiple scattering model of Bianconi and Natoli.
Calculation of the XAFS Debye-Waller Factor with Spherical-Wave Corrections
Authors: Rennert Peter
Published: March 2014

To calculate XAFS spherical-wave corrections and multiple scattering contributions have to be included improving the single scattering plane-wave approximation. A suitable method is described to include such corrections. The temperature dependence of the spectra is determined by a Debye-Waller factor in the plane-wave approximation. An additional temperature dependence arises in a spherical-wave description. An approximative expression is developed, which is valid for the exact angular momentum expansion and any spherical-wave approximation. Due to the thermal movement of the atoms the elements of the t-matrix t

l
have to be replaced by t

l

T
D
=t

l
+k
2 σ10
2 \tildet

l
where \tildet is a modified t-matrix. σ10
2 is the average relative atomic displacement between the emitter and the scatterer. t and \tildet have a different k-dependence. The consequence is as shift in the peaks of the absolut value of the fouriertransformed spectrum. For Ni and NiO we get a shift up to 0.1 atomic units for the nearest and next nearest neighbour.
XAFS Study on Co(II) Polyamine Complexes
Authors: Akai Toshio , Okuda Masami , Horiuchi Kaoru , Matsuura Jun-ichi , Koike Yasuo
Published: March 2014

The XAFS study is performed for a new Co(II) polyamine complex; N,N'-bis(3-aminopropyl) 1,3propanediamine Co(II) complex (Co-APPD), the Co-APPD reacted with oxygen (Co-APPD(O2)), and their solution in DMSO and DMSO with 2-furancarboxylic acid (FRA). The Co-APPD(O2) complex is found to be trivalent and has the similar local structure around Co to that in [Co(NH3)6]Cl3. The difference in the XANES between solid Co-APPD and Co-APPD DMSO solution is quite small. It is considered that the difference of geometrical and electronic structure around Co is also quite small by dissolving Co-APPD in DMSO. Addition of FRA to the Co-APPD DMSO solution changes octahedral structure around Co into tetrahedral structure.
K-XANES Investigations of Some Copper(II) Complexes
Authors: Joshi Santosh Keshav , Soshi Basant Deo , Kumawat Ramesh Chandra , Pandeya Krishna Bihari
Published: March 2014

X-ray absorption near edge structure (XANES) measurements on K edges of copper are employed to study the structure of four copper complexes viz., Cu(dmg)2 [bis-dimethylglyoximato copper(II)]; Cu(sal)2 [bis-salicylaldoximato copper(II)]; Cu(dmg)2Cl2 [chlorine adduct of Cu(dmg)2]; and Cu(sal)2Cl2 [chlorine adduct of Cu(sal)2]. The present XANES studies reveal that metal-ligand bond in Cu(dmg)2 is much more covalent than in Cu(sal)2. For both chlorine adducts, a linear polymeric structure, in which the planar Cu(dmg)2 or Cu(sal)2 units are joined by Cl-Cl molecule, is suggested. The higher values of the edge-shifts in the two chlorine adducts have been attributed to the six coordinate geometry in Cu(dmg)2Cl2 and Cu(sal)2Cl2. The small absorption maxima appearing on the low-energy sides of the main K edge and the principal absorption peak A have been assigned transitions 1s → 3d (empty or partially filled orbitals) and 1s → 4s* respectively.
A Comparative XANES Study of Some Copper(II) Complexes in Solid State and Solution Form
Authors: Shrivastava Basant Deo , Mishra Ashutosh , Joshi Santosh Keshav
Published: March 2014

X-ray K-absorption spectra of some structurally important copper(II) mixed ligand complexes with alpha amino butyric acid as primary ligand have been studied using a Cauchois type bent crystal X-ray spectrograph of 0.4 m radius. The spectra have been recorded using both the solid complexes as well as their aqueous solutions. The observed X-ray absorption parameters e.g., edge-shift, edge-width, shift of the principal absorption maximum and structure of the K-edge have been used to interpret the proposed structure of the complexes. The changes in the structure of the complexes as they form aqueous solutions have also been studied.
Study on Stepwise Copper(II) Chloride Complexes in Acetonitrile by Fluorescence XAFS Spectroscopy Using Thermodynamic Data
Authors: Yamaguchi Toshio , Wakita Hisanobu , Nomura Masaharu
Published: March 2014

Fluorescence X-ray absorption measurements have been performed on dilute acetonitrile solutions of copper(II) chloride with different [Cl-]/[Cu2+] ratios. The absorption spectra for the solvated copper(II) ion, the mono-, di-, tri- and tetrachloro copper(II) complexes have individually been obtained using thermodynamic data. The coordination structures of the stepwise copper(II) species have been determined and are discussed on the basis of the thermodynamic quantities (ΔG

n

o
, ΔH

n

o
, and ΔS

n

o
) for stepwise reaction, CuCl
n-1
(3-n)+ + Cl- = CuCl
n

(2-n)+ (n=1-4).
Stoichiometry of Sulphur in In2S3, CdIn2S4 and AgIn5S8 Single Crystals
Authors: Tezlevan V. E. , Retseev S. A. , Lialikova R. Yu. , Radautsan S. I.
Published: March 2014

Sulphur diffusion process in In2S3, CdIn2S4 and AgIn5S8 single crystals after annealing of these crystals in chalcogen S35 radioisotope contained atmosphere was investigated. Diffusion coefficients D were determined and activation energies were calculated.
Growth of CdSiAs2 Single Crystals by Chemical Transportation
Authors: Noda Yasutoshi , Ohba Masashi , Kurosawa Toshio , Furukawa Yoshitaka , Masumoto Katashi , Oka Yasuo
Published: March 2014

The crystal growth of CdSiAs2 by chemical transport was investigated by using I2, and CdCl2 and CdBr2 as the source of Cl2 and Br2 respectively, for the transport agent. The plate and needle form crystals were grown at the growth zone by CdBr2, while no growth by I2. In case by CdCl2, no transport occurs and the biggest single crystal with the dimensions of 8×3×2 mm3 was obtained at the source zone. The single crystals transported by using CdBr2 had a good-quality judged from no hollow in the crystals and photoluminescence measurement, although the dimensions did not exceed those by CdCl2. The bulk crystal boules were grown by vapor-liquid-solid growth process using CdBr2. The result suggests a possibility of growing a large-size and good-quality single crystal of CdSiAs2.
Chemical Transport Rate of AgGaS2 in a Closed System
Authors: Noda Yasutoshi , Kurasawa Tatsuru , Furukawa Yoshitaka , Niwa Eiji
Published: March 2014

The chemical transport rate in a closed tube was calculated for AgGaS2–I2 system. Using the thermodynamical data of the molecules and the conditions for metal-atom ratio and stoichiometry, the partial pressures of the gaseous molecules were calculated at the source and the growth zones, where Agl(g) was assumed to be equilibrated with Agl(l) in the condensed phase. The transport rates of the gaseous molecules were calculated, from which the transport rate of AgGaS2 was estimated. The transport rate for the growth condition at the source and growth temperatures of 1248 and 1223 K, respectively, monotonously decreased with an increase of amount of iodine and the curve well fitted with the experimental data in the region of more than 0.1 kg/m3 iodine obtained by using AgI as the source of transport agent.
Effect of Heat-treatments on AgGaS2 Photoluminescence
Authors: Kurasawa Tatsuru , Noda Yasutoshi , Furukawa Yoshitaka , Masumoto Katashi
Published: March 2014

Heat-treatments such as Ag2S- and Ga2S3-treatment and Ga dipping were performed and the effect was investigated by measuring the emission intensity of photoluminescence. After the Ag2S-treatment and Ga-dipping, the emission intensity due to free exiton significantly increased which indicates that the quality of single crystals was enhanced and the non-radiative recombination centers were reduced. By the Ga2S3-treatment, the emission intensities changed with an increase of Ga2S vapor pressure, which gave a clear evidence for the emission origins to be Ag and Ga vacancies. After the Ga-dipping, the intensity of red band decreased, supporting that the emission origin is the defect due to excess sulfur.
In(Ti1/2M1/2)O3(MO)m Compounds (M=Zn or Mg, m: Natural Number): Synthesis and Crystal Structures
Authors: Nakamura Masaki , Kimizuka Noboru
Published: March 2014

New homologous compounds In1+x
(Ti1/2Zn1/2)1-x
O3(ZnO)
m
(m=1–11, 0<x≤1) having LuFeO3(ZnO)
m
-type and In(Ti1/2Mg1/2)O3(MgO) having spinel-type are synthesized. The relations between the crystal structures of InAO3(MO) or In(Ti1/2M1/2)O3(MO) (A=Fe, Ga, or Al, M=Zn or Mg) and the constituent cation elements are discussed. The crystal structures of the homologous compounds LuFeO3(ZnO)
m
are compared with those of (In2S3)
n
(ZnS)
m
(m, n: natural number).
Photoluminescence Study of CuIn1-xGaxSe2 Mixed Crystals
Authors: Bacewicz R. , Dzierz\cega A. , Trykozko R.
Published: March 2014

Photoluminescence of CuIn1-x
Ga
x
Se2 mixed crystals has been investigated. The emission band maximum shifts towards higher photon energies with increasing excitation intensity indicating the donor-acceptor recombination mechanism. The energies of the shallow defect states have been determined from the thermal quenching curves.
Electrical and Optical Properties of CuInSe2 Single Crystals with Various Deviations from Stoichiometry
Authors: Nakanishi Hisayuki , Sawaya Takuji , Endo Saburo , Irie Taizo
Published: March 2014

The optical and electrical properties of CuInSe2 single crystals were measured for various deviations from stoichiometry. The absorption curve was found to shift toward the lower energy region with an increase in deviation from stoichiometry. It can be interpreted in terms of Urback rule in connection with the compositional disordering. We have determined the energy levels for the defects in CuInSe2 from the temperature dependence of the carrier concentration and the photoluminescence spectra.
High Energy Spectroscopy of Thin Films of Chalcopyrite Structure Cu–In–Se and Related Materials
Authors: Kohiki Shigemi , Nishitani Mikihiko , Wada Takahiro
Published: March 2014

Effects of non-stoichiometry on the electronic states of chalcopyrite structure Cu–In–Se thin films were evaluated experimentally by X-ray photoemission spectroscopy and predicted theoretically by Hartree-Fock-Slater calculation of [CuSe4] and [InSe4] model clusters.
Metamagnetic Transition and Susceptibility Maximum of Pseudo-Binary Compound (Y, Lu)(Co, Al)2
Authors: Yamada H. , Dubenko I. S. , Levitin R. Z. , Markosyan A. S.
Published: March 2014

A spin fluctuation model for an itinerant-electron metamagnetism developed recently is reviewed. This model gives a simple relation between the high-magnetic field and low-magnetic field phenomena observed for itinerant-electron metamagnets at finite temperature. In order to ascertain the validity of the present model, the temperature dependences of the metamagnetic transition and paramagnetic susceptibility are measured for pseudo-binary compound (Y, Lu)(Co, Al)2 with the cubic Laves phase structure. By the comparison between the theory and experiment, the spin fluctuation model is shown to explain qualitatively the main features in the temperature dependence of the metamagnetic behaviour observed for the present system.
A FLAPW Study of an Unusual Half-Magnetic Material PtMnSb
Authors: Continenza A. , Pascale T. M. de , Meloni F. , Serra M.
Published: March 2014

Heusler ternary compounds reveal very interesting characteristics related to unusually large magneto-optic effect. In this work we perform a first-principles all-electron study of the structural and electronic properties of PtMnSb with particular focus on the projected densities of states for the majority and minority spin components and on the electronic band. In fact, the band structure shows a band gap or a well defined Fermi surface depending on the spin orientation. This peculiarity allows for a semiconductor or a metallic behaviour that can be tuned by an external magnetic field leading to possible application as recording device.
Pressure Effects on Electronic Structure and Magentism of Cu2Sb-Type Compound Mn2Sb
Authors: Suzuki Naoshi , Yoshida Keiichi , Shirai Masafumi , Motizuki Kazuko
Published: March 2014

Total energy calculations by a LAPW method are carried out for paramagnetic, ferrimagneitc and antiferromagnetic states of Mn2Sb. The most stable state obtained is ferrimagnetic, which is in agreement with the observation. For the ferrimangetic state the total energy is calculated as a function of both the lattice constants, a and c and then the linear compressibilities k

a
and k

c
, along the a- and c-axes, respectively, are evaluated. The obtained value of k

c
agrees quite well with the observed data, but the theoretical value of k

a
is smaller by factor two than the experimental data. It is also shown that the rate of magnetic moment reduction by pressure is different for crystallographically inequivalent Mn sites.
Magnetic Properties of the Cr3(S, Se)4-xTex System
Authors: Hashimoto Kimihide , Adachi Yoshiya , Yuzuri Motoyoshi
Published: March 2014

The magnetic and crystallographic properties of Cr3(S, Se)4-x
Te
x
were investigated, where S and Se are at the same atomic ratio. The changes of T
C (Curie temperature), θP (paramagnetic Curie temperature) and lattice constants due to the change of concentration x were observed. It was found that the monoclinic structure became the orthorhombic structure and the anomaly of magnetization disappeared at about x=3.0.
Electronic Structure of Ni Intercalated TiS2 Probed by Angle Resolved and 2p Core Resonance Photoemission as Well as by 2p Core Absorption Spectroscopy
Authors: Kimura Akio , Suga Shigemasa , Matsushita Tomohiro , Imada Shin , Shino Naoyuki , Saitoh Yuji , Shigeoka Hiroaki , Daimon Hiroshi , Kinoshita Toyohiko , Kakizaki Akito , Oh Se-Jung , Negishi Hiroshi , Inoue Masashi
Published: March 2014

Valence band structures of the Ni intercalated TiS2(Ni1/3TiS2) are studied by the angle resolved photoemission spectroscopy (ARUPS). Remarkable dispersions of the intercalated Ni 3d-related band along the c-axis as well as within the layer plane are observed in the ARUPS spectra. Besides, resonance photoemission study is performed in the Ti 2p and Ni 2p core excitation regions to reveal the Ti and Ni derived valence band features. The resonance features are also observed for the core photoemission and Auger electron emission structures.
Magnetic Properties of MnGaGe
Authors: Kanomata Takeshi , Endo Hideharu , Mori Sin-ichi , Sakatsume Shinichi , Yoshida Hajime , Kaneko Takejiro
Published: March 2014

The pressure effect on the Curie temperature (T
c) and the forced magnetostriction for MnGaGe are measured. The value of ∂T
c/∂p is +1.72 K/kbar. The forced magnetostriction at 4.2 K, ∂ω/∂H (ω=Δ
V/V) is found to be +3.81×10-9 Oe-1. The results are discussed using a band theory.
Magnetic Properties of C16 Type Mn1-xFexSn2 Compounds by Mössbauer Study
Authors: Shiraishi Hiroshi , Itoh Kazuo , Hori Tomiei , Kanematsu Kazuo
Published: March 2014

We have measured 57Fe Mössbauer spectra at temperature 13 K and 77 K. The Mössbauer data at 13 K are 120–160 kOe for the hyperfine field H
i, near zero for the quadrupole energy shift Δ
E and 0.6 mm/s for the isomershift. H
i and Δ
E at 77 K show an anomaly between x=0.8 and x=0.85, corresponding to the change of magnetic structure A.F. I\rightleftarrowsA.F. III. The composition x dependence of H
i curve shows an anomalous decrease at x=0.6. The composition dependence of Mössbauer data is discussed in the relation to the sublattice magnetization and the electronic states of Fe.
Magnetic Properties of New Heusler Alloys Ru2MnZ (Z=Si, Ge, Sn and Sb)
Authors: Kanomata Takeshi , Kikuchi Makoto , Yamauci Hiroshi , Kaneko Takejiro
Published: March 2014

New single-phase alloys of the compositions Ru2MnZ (Z=Si, Ge, Sn and Sb) have been prepared. Ru2MnZ (Z=Si, Ge, Sn and Sb) have the L21, (Heusler)-type structure. Ru2MnSi is obtained in partially disordered form (Ru–Si disorder). All alloys are antiferromagnetic.
Exchange Interactions in MxTiS2
Authors: Tazuke Yuuichi , Shibata Shin-ichi , Nakamura Keiko , Yano Hisamasa
Published: March 2014

A trial is made for determining kind of exchange interaction between spins of two intercalation compounds, Fe0.05TiS2 and Co0.1TiS2, by comparing the change in spin glass transition temperature T
g accompanying with the change in conduction electron number. In Co-compound, T
g changes and the RKKY interaction may be the dominant exchange interaction. In Fe-compound, although the change in T
g is small, a tendency for the RKKY interaction is suggested.
Magnetic Properties of Cr2RhSe4 and CrRh2Se4
Authors: Anzai Shuichiro , Ohji Masaaki , Ohta Satoru , Matsukami Tetsuya , Sonokawa Kiyoshi , Matoba Masanori
Published: March 2014

The Néel temperature T
N, the magnetic structural transition temperature T
A and the effective number of Bohr magnetons P
eff (µB/Cr) decrease with increasing y in Cr3-y
Rh
y
Se4. CrRh2Se4 shows a spin glass like state. These features are compared with the magnetic phase diagrams and P
eff of Cr3-x
Rh
x
S4 and Cr3-z
Rh
z
Te4.
Magneto-Optical Study of Reduced Deimensionality and Quantum Confinement in CdTe/MnTe Multiple Quantum Wells
Authors: Takeuchi Yutaka , Ando Koji , Akinaga Hiroyuki , Abe Takashi , Yamamoto Hiroshi
Published: March 2014

CdTe/MnTe multiple quantum well (MQW) structures were grown on sapphire (0001) substrates. Magnetic circular dichroism (MCD) spectra show that these samples have sharp heterointerfaces with monolayer fluctuations. From the temperature dependence of the MCD peak intensity, it is found that the magnetism at heterointerfaces differ distinctly from that of MnTe barrier layers.
Structures and Magnetic Properties of Hf1-xTaxFe2 in Amorphization Process
Authors: Takano Hideaki , Saito Takahiro , Murayama Shigeyuki , Hoshi Kensuke
Published: March 2014

We have studied structural and magnetic properties of a ternary intermetallic compound Hf1-x
Ta
x
Fe2 in the amorphization process using a high-energy ball mill. The X-ray diffracted intensity decreased, whereas the spontaneous magnetization at 0 K increased with the milling time. In Arrott plot analyses, the samples after milling were ferromagnetic. It is suggested that a sample subjected to a ball mill is in the amorphization process and a little disorder generated by the ball milling significantly affects the magnetic properties in this ternary compound system.
Raman Spectra of CuGaxIn1-xSe2
Authors: Tanino H. , Deai H. , Nakanishi Hisayuki
Published: March 2014

We have measured Raman spectra of CuGa
x
In1-x
Se2 (0≤x≤1) single crystals at low temperature. We have examined all Raman active modes. Every phonon shows the linear dependence of the frequency vs the Ga composition x, respectively. The results are in good agreement with the infrared results and our Raman data of CuInSe2, but are inconsistent with the previous report of the Raman spectra of CuInSe2 [J. N. Gan et al.: Phys. Rev. B 13 (1976) 13610].
Analysis of the Electronic States of Phosphorus Interstitials in Phosphorus-Implanted Copper Indium Disulfide by the Molecular Orbital Approach
Authors: Hsu Y. J. , Hwang H. L.
Published: March 2014

The electronic states of the phosphorus interstitials in phosphorus-implanted copper indium disulfide are analyzed by using molecular orbitals. The result shows that electron transfer from the interstitial phosphorus atom to its neghboring sulfur ions occurs in the ground state.
Optical Absorption of ZnGa2S4:Ni2+ and ZnGa2Mn2+ Single Crystals
Authors: Park Hong-Lee , Kim Hyung-Gon , Jeong Hae-Mun , Kim Chang-Dae , Cheon Seung-Ho , Hyun Seung-Cheol , Kim Wha-Tek
Published: March 2014

Single crystals of ZnGa2S4:Mn2+ and ZnGa2S4:Ni2+ were grown by chemical vapor deposition technique. The absorption spectra of these crystals were measured in the wavelength region of 400–3000 nm at 298 K. The optical energy gap is found to be 3.25 eV for the ZnGa2S4, 3.21 eV for the ZnGa2S4:Mn2+ and 3.15 eV for the ZnGa2S4:Ni2+ crystals. Three absorption peaks were observed at 2.30 eV, 2.55 eV and 2.66 eV for the ZnGa2S4:Mn2+ and assigned as, 6A1→4E, 6A1→4T2 and 6A1→4T1 transitions of Mn2+ at Td crystal field. The absorption peaks of ZnGa2S4:Ni2+ were observed at 0.54 eV, 1.14 eV, 1.50 eV, 1.76 eV, 1.94 eV and 2.25 eV. These absorption transitions were assigned as, \varGamma1→\varGamma3+\varGamma4, \varGamma1→\varGamma5, \varGamma1→\varGamma3+\varGamma4, \varGamma1→\varGamma5, \varGamma1→\varGamma4 and \varGamma1→\varGamma3, respectively using Td crystal field along with the 1st order spin-orbit coupling effect.
Site Selective PL Spectroscopy of Cr3+ Ions in CdIn2S4
Authors: Kulikova O. V. , Kulyuk L. L. , Popov S. M. , Tezlevan V. E. , Fortin E.
Published: March 2014

Steady state and time-resolved photoluminescence of Cr3+ ions in CdIn2S4:Cr single crystals has been investigated at resonant excitation. Fluorescence band associated with 4T2g→4A2g vibronic transitions has been observed. The nature of the nonequivalent Cr3+ octahedral sites in partially inversed spinel structure are discussed.
Defect Engineering in II–III2–VI4 and Related Compounds
Authors: Radautsan S. I. , Tiginyanu I. M.
Published: March 2014

Current achievements in controlling the physical properties of II-III2-VI4 defective compounds and their solid solutions by employing different methods of defect engineering are analysed. The main attention is paid to such effects as non-stoichiometry, order-disorder phase transitions as well as to non-equilibrium treatment related phenomena. It has been established that the deviation of II-III2-VI4 compound composition from stoichiometry is accompanied by an intensive formation of antisite cationic defects. A significant disorder is characteristic for the materials containing isoperiodical cations. Ion implantation is shown to be the most perspective tool for the purposive controlling of the physical characteristics. The peculiarities of radiation defect annealing as well as the application purposes of the materials involved for electronic devices possessing a high radiation stability are being discussed.
Optical Properties of ZnxCd1-xInGaS4 System
Authors: Ando Shizutoshi , Endo Saburo , Nakanishi Hisayuki , Toyoda Taro , Irie Taizo
Published: March 2014

We prepared Zn
x
Cd1-x
InGaS4 (x=0–1) crystals by normal freezing method and measured optical absorption, photoluminescence and X-ray diffraction. From the optical absorption, the optical energy gap and the emission peak energy of Zn
x
Cd1-x
InGaS4 system crystals were found to shift to higher photon energy with an increase of the composition x. From the photoluminescence spectra, the emission peak energy was found to shift to higher photon energy.
2.51 eV Donor-Acceptor Pair Photoluminescence from Zn-Doped CuAlSe2 Epilayer Grown by Low-Pressure Metalorganic Chemical Vapor Deposition
Authors: Chichibu Shigefusa , Shirakata Sho , Sudo Ryo , Uchida Mei , Harada Yoshiyuki , Matsumoto Satoru , Higuchi Hirofumi , Isomura Shigehiro
Published: March 2014

A donor to acceptor pair photoluminescence (PL) peak at 2.51 eV was observed in Zn-doped CuAlSe2 epilayers grown by low-pressure metalorganic chemical vapor deposition. The summation of ionization energies of the donor and the acceptor was obtained to be 330 meV from the excitation intensity dependence of the PL peak energy. The Zn impurity is shown to act as a defect-killer because of the apperance of exciton emission at 2.716 eV.
Electronic Structure of Stoichiometric and Reduced SrTiO3(100) Surfaces: A Photoemission Study
Authors: Haruyama Yuichi , Fukutani Hirohito , Aiura Yoshihiro , Nishihara Yoshikazu , Komeda Tadahiro , Kodaira Shuji , Maruyama Takahiro , Kato Hiroo
Published: March 2014

We have performed angle-resolved photoemission and X-ray photoemission studies for Stoichiometric and reduced SrTiO3(100) surfaces. In the empirical band structure of the O2p valence bands along the whole Δ line in the bulk Brillouin zone, there is no essential difference between the Stoichiometric and reduced surfaces. Our results are in excellent agreement with the calculation. In addition to the O2p valence band structure, two new states at ∼1 eV and ∼11 eV below Fermi level appear for the reduced surface (but not for the stoichiometric surface). We show that both of these states are closely connected with oxygen vacancies near the surface.
Electrical and Optical Properties of TlGaSe2 and TlGaSe2:Co Single Crystals
Authors: Yoon Chang-Sun , Kim Byong-Ho , Cha Duk-Joon , Kim Wha-Tek
Published: March 2014

Optical absorption and dielectric properties have been investigated for TlGaSe2 and TlGaSe2: Co single crystals grown by Bridgman method. The temperature dependence of the exciton peak position in TlGaSe2 showed the anomalies at 50 K, 90 K, 107 K and 120 K. The dielectric anomalies of TlGaSe2 are found which exhibit structural phase transitions (PT) at T
2=107 K and T
1=120 K corresponding to first-order and second-order PT, respectively. It is found that an increase in concentration of Co impurity leads to shift of two phase transition points (T
1 and T
2) towards the lower temperature and changes the dielectric properties for TlGaSe2: Co. The impurity absorption bands observed in TlGaSe2: Co are attributed to the electronic transitions between the split energy levels of Co2+ ions with tetrahedral (T
d) symmetry in TlGaSe2 host lattice.
Co Impurity Effect in Zn1-xCoxSe Crystals Grown under Equilibrium Condition
Authors: Hwang Insun , Choi Young Seok , Kim Jae-Eun , Park Hae Yong , Lim H. , Park Hong-Lee
Published: March 2014

The influences of Co impurity in the Zn1-x
Co
x
Se crystal were investigated by X-ray diffractometry (XRD) and Raman spectroscopy using melt grown Zn1-x
Co
x
Se polycrystals. The solid solubility of Co atom in melt grown ZnSe crystal is about x=0.02±0.0015. The solid solubility of magmetic ions may depend on the electronegativity and covalent radius. It was found that the lattice constant of the crystal increases linearly up to x=0.0086 and then saturates as the amount of Co impurity increases. It is also observed that the TO2 and LO1 Raman modes in Zn1-x
Co
x
Se grown under equilibrium condition soften in the value of x<0.0086 by the addition of Co atoms. There is a linear relationship between the ionicity and the oscillator strength which is calculated using the energies of TO2 and LO1 phonon modes with the slope of -7.02×1025 (s-2). From these observations it is clear that the instability of Zn1-x
Co
x
Se crystal is mainly due to the ionicity difference between Zn and Co atoms since both covalent radii are almost the same.
Optical Properties of Undoped and Co-Doped Zn0.5Mg0.5Te Single Crystals
Authors: Kim Yong-Geun , Kim Chang-Dae , Kim Hyung-Gon , Yang Dong-Ik , Kim Wha-Tek
Published: March 2014

Zn0.5Mn0.5Te and Zn0.5Mg0.5Te:Co2+ single crystals were grown by chemical transport reaction (CTR) method which is applied to the temperature modulation method. The energy gaps of the grown single crystals at 298 K are 2.340 eV for Zn0.5Mg0.5Te and 2.213 eV for Zn0.5Mg0.5Te:Co2+. The temperature dependence of the energy gap is well represented by the Varshni equation. Impurity optical absorption of Zn0.5Mg0.5Te:Co2+ single crystal is described by the electronic transitions between energy levels of Co2+ ion which is sited at T
d symmetry point in the crystal.
Optical Properties of CuAlSe2 Single Crystal
Authors: Jin Moon-Seog , Min Suk-Ki , Lim Han-Jo , Park Hong-Lee , Kim Wha-Tek
Published: March 2014

CuAlSe2 single crystal was grown by chemical transport reaction (CTR) method. The starting material was initially prepared by a melt grown technique in a rotating horizontal furnace using the elements, Cu, Al and Se (99.9999% purity) with the excess selenium of 3 mole% from the stoichiometric quantity. In photoluminescence spectra measured at 80 K, two types of broad emission bands of which the peak energies were 1.77 eV (L-photoluminescence) and 1.93 eV (Hphotoluminescence) are observed, where each of the bands is, respectively excited by the 477 nm line of Ar-ion laser and 337 nm line of N2 gas laser. From the excitation spectrum and the thermally stimulated current (TSC) spectrum, these emission bands are analyzed as the D-A pair photoluminescences.
Optical Properties of Cd4GeSe6 and Cd4GeSe6:Co2+ Single Crystals
Authors: Kim Duck-Tae , Yu Ki-Su , Kim Yong-Suk , Kim Jae-Eun , Park Hae-Yong , Park Hong-Lee , Kim Wha-Tek
Published: March 2014

The optical absorption and photoluminescence spectra of undoped and cobalt doped Cd4GeSe6 single crystals are presented. The Cd4GeSe6:Co2+ absorption spectrum was analysed in terms of Co2+ ion T
d site along with the spin-orbit coupling effects. Two donor and two acceptor levels were identified along with multiphonon processes in photoluminescence study of Cd4GeSe6.
Luminescence Spectra of the CuAlSe2 Single Crystals Doped by the Elements of the II Group
Authors: Savchuk V. A. , Lipnitskii V. I. , Korzun B. V. , Makovetskii G. I.
Published: March 2014

Single crystals of CuAlSe2 were prepared by the iodine vapour transport technique and annealed in the atmosphere of Zn, Cd, Cd+Al. The cathodoluminescence investigations were carried out at 77 and 300 K. The obtained results suggest the possibility of using this material in light-emitting devices.
Photo-Induced Absorption in Bi12SiO20:Cr Crystals
Authors: Račlukaitis G. , Gavryushin V. , Kubertavičius V. , Puzonas G.
Published: March 2014

Pulse-laser-induced phenomena are investigated in undoped and Cr-doped Bi12SiO20 crystals. For undoped crystals an anomalous behavior of photochromic effect caused by intensive IR-laser radiation is actual. In Bi12SiO20:Cr, photo-induced absorption occurs in the region of intra-center transition of Cr4+-ion as a consequence of carrier exchange between the conduction band and Cr-ion.
Thermal Decomposition of Ternary Chalcopyrite Thin Films
Authors: Ruckh M. , Kessler J. , Oberacker T. A. , Schock H. W.
Published: March 2014

Polycrystalline thin films of the ternary chalcopyrite semiconductors CuIn3Se5 and CuInSe2, prepared by a coevaporation process, have been investigated with the Temperature Programmed Desorption method (TPD). The desorbing species have been detected with a mass spectrometer for temperatures up to 750°C. Morphological changes have been observed with SEM and compositional data have been recorded before and after the heat treatments. The decomposition process has been found to start at about 500°C with outgasing of Se2 species, followed by the desorption of In2Se starting at 600°C. CuIn3Se5 thin films could be transformed totally to Cu2Se.
Magnetic and Transport Properties of Ternary Chalcogenides, BaMS3 (M=V, Nb, Ti)
Authors: Matsuura Kiyotaka , Nakamizo Takashi , Wada Takahiro , Yamauchi Hisao , Tanaka Shoji
Published: March 2014

BaVS3 is known to a metal-to-semiconductor transition and a para-to-antiferromagnetic transition around 70 K. Upon substituting a small amount (5%) of Ti or Nb for V in BaVS3, the electrical conduction above 70 K became semiconductive, and the magnetism became paramagnetic throughout the temperature range of 4.2 K to 300 K. BaNb1-x
Ti
x
S3 (0.0≦x≦1.0) were found to be thermal-activation-type semidocnductive and weakly diamagnetic below 300 K. These phenomena were thought to be caused by the formation of Nb–Nb dimers.
Anisotropy of the Charge Carrier Transport in II–IV–V2 Single Crystals
Authors: Rud' V. Yu. , Rud' Yu. V.
Published: March 2014

The temperature dependences of the electrical conductivity and of the Hall coefficient were determined for oriented II-IV-V2 single crystals. From the measurements of temperature dependence of the Hall constant, the Hall effect of II-IV-V2 single crystals is isotropic. An anisotropy of the Hall mobility of hole was detected experimentally in the CdGeAs2 and CdSiAs2 single crystals. The hole mobility anisotropy in ZnGeP2 was not determined. The knowledge of the anisotropy of the Hall mobility should help to improve the efficiency of semiconductor electronic devices made of II-IV-V2 materials.
Torque Study on the High-Tc Y1Ba2Cu3O7-y Superconductor
Authors: Kim Mun-Seog , Kim Kyeong-Sup , Yu Seong-Cho
Published: March 2014

The magnetic torque in the Y1Ba2Cu3O7-y
high-T
c superconductor was measured by rotating the magnet relative to the sample. A concept of fluxoid dispersion was introduced, and the magnetic torque in Y1Ba2Cu3O7-y
superconductor was quantitatively interpreted for the first time.
Site-Correlated-Adsorption Induced Atomic Ordering in Heteroepitaxial Alloy Semiconductors
Authors: Nakayama Hiroshi , Tochigi Makoto , Nishino Taneo
Published: March 2014

A phenomenological theory to describe consistently atom incorporation processes, compositional fluctuation and short-range atomic ordering in ABC//BC type alloy semiconductors grown by molecular-beam epitaxy (MBE) has been presented. A concept of “site-correlated adsorption” has been introduced here to describe the difference in the local atomic configurations of the adsorption sites at growing surface. Especially, inter-layer inter-atomic interactions between surface atoms(sites) and the underlying atoms(sites) have been found to be quite important. Sticking coefficients, which can be measured experimentally, of A and B atoms of AIIIBIIICV//BIIICV alloy is formulated using the site-correlated adsorption probabilities. It has been found that molecular-beam-flux dependence of sticking coefficients, compositional fluctuation at the interface between substrate and epitaxial layer, short-range atomic ordering can be explained in the framework of present theory of atom-sticking coefficient in MBE using the site-correlated adsorption probabilities.
Raman and Infrared Spectra of Amorphous Semiconductors (GeS2)1-x(Sb2S3)x Systems
Authors: Asami Takehisa , Onari Seinosuke , Arai Toshihiro
Published: March 2014

Polarized Raman spectra and far infrared spectra of amorphous (GeS2)1-x
(Sb2S3)
x
systems (0≦x≦0.9) were measured. The Raman spectra due to Sb2S3 component showed strong polarization dependences. The optical constants were calculated by Kramers-Kronig analysis of the infrared reflection spectra, and were also analyzed by the classical oscillator models. The effective charges of Sb ion were calculated. The results of the Raman and infrared spectra show that SbS3 pyramidal unit is predominant in the local structure around Sb atom in these amorphous systems.
Influence of Morphology and Structure of Cu/In Alloys on the Properties of CuInSe2
Authors: Parretta Antonio , Addonizio Maria Luisa , Agati Antonio , Pellegrino Michele , Quercia Luigi , Cardellini Francesco , Kessler J. , Schock H. W.
Published: March 2014

Thin CuInSe2 films were prepared by selenization of sputtered metal precursors. The surface morphology, phase composition and adhesion at the Mo/glass substrate of the ternary compound have been correlated to the structure of the precursor. Single phase, homogeneous, small grained (1 µm) CuInSe2 arises from precursors showing stable phases (Cu11In9 and In). An ordered vacancy compound (CuIn3Se5) is likely present in In-rich (In>27 at.%) films. Precursors with a high content of the metastable CuIn2 phase show a very poor adhesion to the substrate.
CuInSe2 Thin Film Prepared by Evaporation of Cu2Se and In2Se3
Authors: Ashida Atsushi , Hachiuma Yoshio , Yamamoto Nobuyuki , Ito Taichiro , Cho Yoshio
Published: March 2014

Preparation of CuInSe2 thin films by evaporation of In2Se3 and Cu2Se is proposed. Sequential evaporation of In2Se3 and Cu2Se is superior in controlling composition of films and the p-type film with 24 cm2/V·s in Hall mobility is obtained. By heating substrates during deposition and using rf plasma, we have succeeded in obtaining the <112> highly oriented CuInSe2 thin films.
Formation and Microanalysis of Selenized CuInSe2 Films
Authors: Tseng B. H. , Chang Y. C. , Lin S. B. , Hwang H. L.
Published: March 2014

Cu/In bilayer, Cu/In multilayer, and Cu–In mixed layer structures had been evaluated as the base layer for the selenization of CuInSe2 films. Auger depth profiling showed that Cu/In multilayer had the most uniform elemental distributions and so did the selenized film made from it. The sequence of phase formation during selenization process was also studied. The reaction paths were found to be changed as the Cu/In ratio varied from 0.9 to 0.45.