Temat: 65.40.-b - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Low Temperature Specific Heat of BiOX (X = Cl, Br, and I) Single Crystals
Autorzy:: Bunda, V.
Bunda, S.
Kajňakova, M.
Feher, A.
Syrkin, E.
Feodosyev, S.
Tematy:: 65.40.-b
63.22.Np; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1535050.pdf Link otwiera się w nowym oknie
Opis:: Low temperature specific heat of layered bismuth oxyhalide crystals has been studied in the temperature range from 2 to 50 K in zero and 8 T magnetic field. The expected Debye-like behaviour at the lowest temperatures (below 4-5 K) is established. Linear dependences of entropy and the Debye temperature as cross-correlation parameters are established. The small values of the Debye temperature and peculiarities of phonon spectra at lowest temperatures are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Mechanical and Thermal Properties of Individual Phases Formed in Sintered Tungsten-Steel Composites
Autorzy:: Matějíček, J.
Nevrlá, B.
Čech, J.
Vilémová, M.
Klevarová, V.
Haušild, P.
Tematy:: 62.20.-x
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1402135.pdf Link otwiera się w nowym oknie
Opis:: Tungsten is a prime candidate material for plasma facing components in fusion devices, thanks to its advantageous properties with respect to interaction with hot plasma. For its bonding to the supporting structure, composites and graded layers can be used for the reduction of stress concentration at the interface. When tungsten and steel are processed at elevated temperatures, e.g. hot pressing or spark plasma sintering, intermetallic phases may form and their presence and properties will affect the properties of the composite. In this work, mechanical and thermal properties of the individual phases, i.e. steel, tungsten and Fe-W intermetallics are investigated. Mechanical properties were determined by instrumented indentation. Thermal conductivity was determined by the xenon flash method on a range of samples with varying composition, from which the conductivities of each constituent were estimated. The results can be used for the optimization of compositional profiles and processing conditions for manufacturing of plasma facing components.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Energy Spectrum for the System of N Ising Spins with Identical Spin-Spin Coupling K/N - Anatomy of Phase Transition
Autorzy:: Czachor, A.
Tematy:: 75.50.Kj
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813172.pdf Link otwiera się w nowym oknie
Opis:: For the Kittel-Shore-Kac interspin coupling K/N between N Ising spins the ferromagnetic phase transition in specific heat vs. T plot has appeared in literature as a purely mathematical phenomenon, via the exact calculation of the sum of states Z(T) and subsequent differentiations with respect to temperature T. Physical nature of the transition remains in such derivation invisible. As it is expected to be related to the interaction/temperature competition in populating energy levels of the system, in this paper we construct the density of energy states D(E) (or energy spectrum) of such systems, both for the ferromagnetic (K>0) and antiferromagnetic (K<0) coupling between spins. This allows one to see the essence of the difference between these systems as related to the discrete vs. quasi-continuous shape of the spectra at low energy states.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: A Study of Optical Uniformity of Lithium Niobate and Paratellurite Crystals by the Method of Conoscopy
Autorzy:: Kolesnikov, A.
Tretiakov, S.
Grechishkin, R.
Morozova, K.
Yushkov, K.
Molchanov, V.
Linde, B.
Tematy:: 42.79.Jq
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1383456.pdf Link otwiera się w nowym oknie
Opis:: An exact equation of the isochromatic fringes of uniaxial crystals derived without usually adopted simplifications is presented. It enables to calculate the optical conoscopic figures for ideal crystals with different angular orientations of the optical axis with respect to the normal to the crystal surface. Conoscopic figures of large-size single crystals of lithium niobate and paratellurite were examined experimentally making use of a laser-based setup. The conoscopic figure evolution in operating acousto-optic devices was studied.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Lattice Parameters of Aluminium Nitride in the Range 10-291 K
Autorzy:: Paszkowicz, W.
Knapp, M.
Podsiadło, S.
Kamler, G.
Pełka, J. B.
Tematy:: 81.05.Je
65.40.De
65.60.+a
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2030706.pdf Link otwiera się w nowym oknie
Opis:: Lattice parameters for aluminium nitride were determined using X-ray powder diffraction at a synchrotron radiation source (beamline B2, Hasylab/DESY, Hamburg) in the temperature range from 10 K to 291 K. The measurements were carried out using the Debye-Scherrer geometry. The relative change of both, a and c, on rising the temperature in the studied range (10-291 K) is about 0.03%. The results are compared with earlier laboratory data and theoretical predictions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The Electronic Structure and Specific Heat of $YNi_4Si$
Autorzy:: Pugaczowa-Michalska, M.
Falkowski, M.
Kowalczyk, A.
Timko, M.
Reiffers, M.
Mihalik, M.
Šebek, J.
Šantava, E.
Tematy:: 71.20.Be
71.20.-b
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813671.pdf Link otwiera się w nowym oknie
Opis:: The studies of the electronic structure and the specific heat of $YNi_4Si$ are reported. Below the Fermi energy $(E_F)$ the density of states contains mainly the 3d states of Ni, which hybridized with 4d states of Y and 3p states of Si. The theoretical electronic specific heat coefficient (12.32 mJ/(mol $K^2$)) obtained for equilibrium lattice parameters and the experimental value (13 mJ/(mol $K^2$)) are in a reasonable agreement.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Optoelectronic, Elastic and Thermal Properties of Cubic Perovskite-Type SrThO₃
Autorzy:: Benaissa Cherif, Y.
Rouaighia, M.
Zaoui, A.
Boukortt, A.
Tematy:: 78.20.Ci
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1033479.pdf Link otwiera się w nowym oknie
Opis:: The electronic structure, elastic, thermal and optical properties of the cubic strontium thorate SrThO₃ are calculated using the full-potential linearized augmented plane wave method (FP-LAPW) based on the density functional theory with generalized gradient approximations GGA and local density approximation LDA. The modified Becke-Johnson potential (mBJ) is applied in electronic structure for calculating the energy gap. The obtained results are the Young modulus, shear modulus, the Poisson ratio, isotropic shear modulus, longitudinal, transverse and average sound velocities, the Zener anisotropy factor, the Kleinman parameter and the Debye temperature of the systems. All results are discussed and compared with the available experimental data.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: High-Pressure Phase Transitions and Thermodynamic Behaviors of Cadmium Sulfide
Autorzy:: Tan, J.
Li, Y.
Ji, G.
Tematy:: 71.15.Mb
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1493632.pdf Link otwiera się w nowym oknie
Opis:: The pressure-induced phase transitions of cadmium sulfide semiconductor in both zinc-blende and wurtzite structures are investigated by ab initio plane-wave pseudopotential density functional theory with the local density approximation. On the basis of the fourth-order Birch-Murnaghan equation of state, the phase transition pressures $P_{t}$ are determined by the enthalpy criterion. It is found that the phase transitions occur at pressure of 2.57 GPa (zinc blende-rocksalt structure) and 2.60 GPa (wurtzite-rocksalt structure), respectively. The equilibrium structural parameters, elastic constants, and phase transition pressures are calculated and compared with the experimental data available and other theoretical results. According to linear-response approach, the thermodynamic properties such as the free energy, enthalpy, entropy, and heat capacity are also obtained successfully from the phonon density of state.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Thermodynamics of Fcc Al Crystal from First Principles - Performance of Local Density and Generalized Gradient Approximations
Autorzy:: Scharoch, P.
Peisert, J.
Tatarczyk, K.
Tematy:: 65.40.-b
63.20.Dj; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2047735.pdf Link otwiera się w nowym oknie
Opis:: Phonon dispersion relations in fcc Al crystal were calculated from first principles using density functional perturbation theory, as implemented in ABINIT code. The results are compared with experimental data as well as with the results of previously done ab initio calculations based on the direct method. A slightly better agreement of density functional perturbation theory phonons with experiment can be observed. The ab initio phonon energies were used to evaluate the partition function of the crystal, using the Monkhorst-Pack integration scheme. The quasiharmonic approximation was applied to relate the temperature dependent part of the free energy to volume. The lattice constant dependence of phonon energies was found to be almost linear, so the second order polynomial was considered as sufficient to approximate the dependence. A few examples of thermodynamic characteristics were evaluated: isobaric specific heat, linear thermal expansion coefficient, isothermal bulk modulus, and compared with the experimental data. The calculation was done both in the local density and the generalized gradient approximations for the exchange-correlation energy. The agreement with the experimental data appears to be very satisfactory, although better in the local density approximation than in the generalized gradient approximation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Dielectric and Birefringent Properties of [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ Solid Solutions in the Region of Their Phase Transitions
Autorzy:: Eliyashevskyy, Yu.
Kapustianyk, V.
Dacko, S.
Czapla, Z.
Batiuk, A.
Sveleba, S.
Tematy:: 65.40.-b
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2044636.pdf Link otwiera się w nowym oknie
Opis:: On the basis of the optical and dielectric investigations of [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ solid solutions the existence of phase transitions at T$\text{}_{1}$=175 K and T$\text{}_{2}$=117.5 K was confirmed. Both phase transitions were found to be shifted toward lower temperatures with respect to the corresponding transitions in the "host" [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{3}$Cl$\text{}_{11}$ crystals. It was found that the proton conductivity in [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$ ]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ crystals is realized through the Grotthus mechanism. The investigations of the birefringent properties confirmed existence of the structural changes at T$\text{}_{0}$=320 K connected with the complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn-Teller distortion with temperature.
Dostawca treści:: Biblioteka Nauki

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