This paper deals with the growth of Bi 2 Se3 crystal by newly designed experimental set-up of Bridgman
technique in our laboratory. Grown crystal is characterized by EDAX (Energy Dispersive Analysis ...of X-rays),
XRD (X-ray Diffraction), low temperature thermopower measurements (17-284 K), resistivity measurements
(16-294 K) and Hall Effect at room temperature in order to study its various properties. The surface study
of the grown crystal using AFM (Atomic Force Microscopy) shows a hexagonal unit cell shape whose internal
angle determined comes out to be nearly equal to 122.94◦ which has close resemblance with an angle of
120◦ of perfect internal angle of hexagon. Various parameters obtained from above measurements like lattice
parameters, crystallite size and stacking fault probabilities are discussed in detail in the paper.
$InBi_{0.85}Sb_{0.15}$ single crystals have been grown by zone-melting method. The growth velocity was
0.8 cm/h and the freezing interface temperature was 35 ◦C/cm. A Vickers' projection ...microscope was
used for the study of micro hardness of the crystals. Hardness tests were carried out on the as-cleaved,
cold-worked and annealed surfaces of the crystals. The effect of perfection of crystals on micro hardness
with respect to the cold-worked, as-cleaved and annealed crystals have been studied and the results are reported.
Frictiewas, brokken bruinig hoogkristallijn was van hogere smelttemperatuur met slagvlakken zoals ook bij vuursteen te zien. Paar slijpvlakken met verhittingsbelletjes op plaatsen waar brok tegen ...drijfriemen gehouden is.
Raman scattering spectra of CdInGaS4 crystals grown by the chemical transport method were measured at room and liquid-nitrogen temperatures. Band pairs at 29-38, 43-48 and 60-65 $cm^{-1}$ are ...reported for the first time. The origin of these bands is attributed to the Davydov doublets, arising due to a small interlayer interaction. Seventeen bands observed in the Raman spectra are assigned to normal modes on the basis of the GSV space group. This modification contains two layers per unit cell and do not have inversion symmetry. It is shown that the crystals grown from the vapor phase and by the Bridgman method belong to different modifications.
PACS: 78.20. -e; 78.30. _j; 78.30. Hv
Single crystals of $Mo_{0.5}W_{0.5}S_2$ were grown by chemical vapour transport and direct vapour transport techniques. The crystals have been characterized by X-ray energy dispersive analysis and ...X-ray powder diffraction. The dc electrical resistance of the grown single crystals of $Mo_{0.5}W_{0.5}S_2$ was measured in Bridgman anvil setup to 8 GPa to identify occurrence of structural phase transitions. The drastic changes
in electrical resistance were observed at~ 2.5 GPa and ~4.6 GPa, and are similar to the structural phase transitions in WS2 single crystals.
In the present work, crystal structure and optical properties of the layered chalcogenides
$GaS_xSe_{1-x}$, GaSe, $TIGaSe_2$ and $TIInS_2$ were investigated in the visible (VIS) and infrared (IR) ...range of spectra.
Partial content of the elements were performed and the space group were determined by help of X-ray
diffraction experiments. Making use of the experimental results, we have constructed a scheme of band
motion for the transition from GaSe to GaS. It has been established that that the infrared active optical
modes show typical two-mode behaviour.
By employing the method of electrostatic potential expansion, the interface optical (10) and surface optical (SO) phonon modes and the corresponding Fröhlich-like electron-phonon-interaction ...Hamiltonian in a QID wurtzite cylindrical quantum well wire (QWW) embedded in nonpolar dielectric matrix are derived and studied based on the dielectric continuum model and Loudon's uniaxial crystal model. Numerical calculations for a wurtzite GaN/AIN QWW are mainly focused on the size- and dielectric-dependent IO and SO phonon spectra and electron-IO (SO)phonons coupling functions. Results reveal that, in general, there are two branches of IO phonon modes and one branch of SO mode in the system. The dispersions of the IO and SO modes are obvious only when the radii ratio $\beta$ and the dielectric constant of nonpolar matrix ea is small. The limiting frequencies of IO and SO modes for very large (5 have been analyzed in depth from both physical and mathematical viewpoints. The reducing behaviors of some modes have been clearly observed. Via the discussion of electrostatic potential spacial distributions of the IO and SO modes, we find that the QWW structures and dielectric constants of nonpolar matrix have little influence on the low-frequency IO mode, but they can greatly affect the potential distributions of high-frequency IO mode and SO mode. Detailed comparison of the dispersion behaviors of the modes and electron-phonon coupling properties in the QID wurtzite QWWs with those in wurtzite QWs and cubic quantum dots has also been made. Furthermore, part of the theoretical results derived in the present paper is consistent with the relatively experimental conclusion.
Serat kristal fotonik (SKF) adalah pandu gelombang cahaya dengan sebuah inti padat pada pada pusat dikelilingi susunan lubang udara dengan struktur geometri tertentu. Variasi ukuran dan jarak antar ...lubang udara serat kristal fotonik membuat dispersinya dapat dikontrol untuk mendapatkan dispersi minimal bagi aplikasi sistem komunikasi optis. Dispersi serat kristal fotonik diperoleh setelah terlebih dahulu memecahkan Persamaan Maxwell untuk mendapatkan konstanta propagasi, β, yang pada penelitian ini dipakai kombinasi metode compact 2D finite difference time domain (FDTD) dan compact 2D finite difference frequency domain (FDFD). Setelah β diperoleh, maka indeks bias efektif, neff, dihitung lalu dilakukan pencocokan kurva guna mendapatkan diferensial orde dua neff terhadap panjang gelombang λ (d2neff/dλ2). Nilai (d2neff/dλ2) disubstitusikan ke dalam persamaan dispersi D. Dilakukan perhitungan D pada tiga konfigurasi SKF dengan variasi radius lubang udara r dan jarak lubang udara a. Didapat hasil bahwa terjadi perubahan D akibat variasi tersebut. Pada SKF dengan konfigurasi r = 0.25 μm dan a = 2 μm, diperoleh ultraflattened dispersion pada rentang panjang gelombang 1300 nm-1450 nm yaitu sebesar -2.2496 ps/nm.km hingga 1.8653 ps/nm.km. Hasil ini menunjukkan bahwa SKF konfigurasi ketiga cocok diaplikasikan pada sistem komunikasi optis.
