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Tytuł:
DSC Studies of Some Bismuth-phosphate Glasses
Autorzy:
El-Adawy, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/1992707.pdf
Data publikacji:
1998-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.+g
Opis:
The differential scanning calorimetry measurements were made on a series of bismuth-iron-phosphate glasses over a temperature range around the glass transition temperature. The activation energy for structural relaxation, ΔH, was determined and found to increase with the metal-to-phosphorus ratio. The differential scanning calorimetry data were analyzed using the Adam-Gibbs-Scherer model of the glass transition. This analysis suggests that these glasses undergo a transition from the strong to the fragile glass regime as the metal-to-phosphorus ratio is increased.
Źródło:
Acta Physica Polonica A; 1998, 94, 4; 661-670
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multispectral Laser Head for Terrain Identification and Analysis
Autorzy:
Mierczyk, Z.
Zygmunt, M.
Kaszczuk, M.
Muzal, M.
Powiązania:
https://bibliotekanauki.pl/articles/1399385.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.70.Ce
65.40.G-
42.62.-b
Opis:
The reflectance profilometer, constructed in Institute of Optoelectronics, Military University of Technology, is an optoelectronic device based on the laser remote sensing technique, designed for use on unmanned aerial vehicles. The main task of the profilometer is to analyze the reflectance signals for laser radiation from the multispectral range: 850, 905, and 1550 nm. On the basis of the analysis the profilometer enables two fundamental functions: to define the shape of the ground and identify elements of terrain coverage, along with analysis of its physicochemical properties. The reflectance profilometer is a system based on a modern concept of measurement, allowing to obtain unique information about tested objects, whose measurements or detection are not possible by means of thermal imaging systems and systems operating in the visible range. The received information is visualized in 3D format, which allows for more accurate, precise and comprehensive way of analyzed area model presentation.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 502-504
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Phase Transition in $CeCuAl_{3}$ Single Crystal
Autorzy:
Klicpera, M.
Javorský, P.
Daniš, S.
Brunátová, T.
Powiązania:
https://bibliotekanauki.pl/articles/1369117.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.C-
65.40.G-
66.70.Df
Opis:
The high temperature properties of $CeCuAl_{3}$ single crystal were investigated by differential scanning calorimetry and high-temperature x-ray diffraction. The structural phase transition takes place around 300 °C. The phase transition changes the structural parameters only, the tetragonal $BaNiSn_{3}$-type structure is preserved. The significant changes of lattice parameters and especially atomic fraction coordinates with this transition are discussed with respect to the number of heating/cooling cycles and stability in time. Magnetic properties of as-cast and annealed sample are shown for comparison.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 290-291
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Enthalpy of Solution of Cobalt and Nickel in Iron Studied with $\text{}^{57}Fe$ Mössbauer Spectroscopy
Autorzy:
Idczak, R.
Konieczny, R.
Konieczna, Ż.
Chojcan, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506574.pdf
Data publikacji:
2011-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
82.60.Lf
65.40.G-
Opis:
The room temperature Mössbauer spectra of $\text{}^{57}Fe$ were measured for iron-based solid solutions $Fe_{1-x}Co_{x}$ and $Fe_{1-x}Ni_{x}$ with x in the range 0.01 ≤ x ≤ 0.05. The obtained data were analysed in terms of the binding energy $E_{b}$ between two Co or Ni atoms in the studied materials using the extended Hrynkiewicz-Królas idea. It was found that the energy is positive or the non-iron atoms interact repulsively. The extrapolated value of $E_{b}$ for x=0 was used for computation of the enthalpy of solution of cobalt and nickel in iron. The results were compared with our previous Mössbauer spectroscopy findings, the values resulting from the Miedema's model of alloys and the data derived from the enthalpy of formation of the Fe-Co and Fe-Ni systems, obtained with calorimetric methods. The comparison shows that the present results are in a qualitative agreement with the Miedema's model predictions and calorimetric measurements but they are at variance with the previous Mössbauer spectroscopy findings.
Źródło:
Acta Physica Polonica A; 2011, 119, 1; 37-40
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat Capacity and Elastic Constants of Fe$\text{}_{3-x}$Zn$\text{}_{x}$O$\text{}_{4}$ in the Vicinity of the Verwey Transition
Autorzy:
Kozłowski, A.
Kąkol, Z.
Schwenk, H.
Bareiter, S.
Hinkel, C.
Luthi, B.
Honig, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2013722.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
63.20.-e
64.60.-i
65.40.+g
Opis:
The results of the heat capacity and elastic constant studies of Fe$\text{}_{3-x}$Zn$\text{}_{x}$O$\text{}_{4}$ (x<0.04) series are reported. Adiabatic heat capacity measurements, performed on single crystals, show the clear change of the transition character from first order for low Zn content (x<0.012) to the higher order in 0.012
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 883-887
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice Parameters of Aluminium Nitride in the Range 10-291 K
Autorzy:
Paszkowicz, W.
Knapp, M.
Podsiadło, S.
Kamler, G.
Pełka, J. B.
Powiązania:
https://bibliotekanauki.pl/articles/2030706.pdf
Data publikacji:
2002-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
65.40.De
65.60.+a
65.40.-b
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.
Źródło:
Acta Physica Polonica A; 2002, 101, 5; 781-785
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Persistent Currents and Bethe Ansatz
Autorzy:
Kiršanskas, G.
Matulis, A.
Powiązania:
https://bibliotekanauki.pl/articles/1505510.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Gk
03.65.Nk
Opis:
The system of two electrons interacting with a single impurity in 1D metallic ring is considered illustrating the applicability of the Bethe Ansatz.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 158-160
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical Determination of the PZTs Distribution in Active Beam Vibration Protection Problem
Autorzy:
Brański, A.
Lipiński, G.
Powiązania:
https://bibliotekanauki.pl/articles/1504198.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Tm
43.40.Vn
77.65.-j
46.40.-f
62.25.Jk
Opis:
The paper concerns an active vibration protection (p-reduction) of the structure via piezoelectric transducers; p-reduction corresponds to an active vibration reduction (a-reduction). The quantity and effectiveness of the (a- or p-) reduction, among other parameters, depend on the piezoelectric transducers distribution on the structure. The best results are obtained bonding piezoelectric transducers to the structure in the sub-domains with the largest curvatures; it is so-called quasi-optimal distribution of the piezoelectric transducers. Up to now, the quasi-optimal distribution was determined based on heuristic reasons only. The aim of the paper is to confirm quasi-optimal distribution in analytical way. The beam clamped at one end, vibrating with first three modes separately, is chosen as the research object. It is assumed that the piezoelectric transducers are exactly the same. Demanding the vibration amplitude to be equal to zero (i.e. p-reduction condition), the general formula for interacting forces piezoelectric transducers-beam is derived. Next, such an appropriate distribution of piezoelectric transducers is searched analytically, that the minimal forces are achieved; it leads to the best reduction effectiveness. It turned out that the analytical method pointed out quasi-optimal distribution of the piezoelectric transducers. The validation of theoretical considerations is confirmed numerically.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 936-941
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF₃
Autorzy:
Harmel, M.
Khachai, H.
Haddou, A.
Khenata, R.
Murtaza, G.
Abbar, B.
Bin Omran, S.
Khalfa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402310.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.de
65.40.Ba
65.40.De
Opis:
We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF₃ perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke-Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities $C_V$ and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 34-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Pressure Phase Transitions and Thermodynamic Behaviors of Cadmium Sulfide
Autorzy:
Tan, J.
Li, Y.
Ji, G.
Powiązania:
https://bibliotekanauki.pl/articles/1493632.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
65.40.-b
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.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 501-506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multifractal Background Noise of Monofractal Signals
Autorzy:
Grech, D.
Pamuła, G.
Powiązania:
https://bibliotekanauki.pl/articles/1408977.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.Tp
89.75.Da
05.40.-a
89.75.-k
89.65.Gh
Opis:
We investigate the presence of multifractal residual background effect for monofractal signals which appears due to the finite length of the signals and (or) due to the constant long memory the signals reveal. This phenomenon is investigated numerically within the multifractal detrended fluctuation analysis (MF-DFA) for artificially generated time series. Next, the analytical formulas enabling to describe the multifractal content in such signals are provided. Final results are shown in the frequently used generalized Hurst exponent h(q) multifractal scenario as a function of time series length L and the autocorrelation scaling exponent value γ. The obtained results may be significant in any practical application of multifractality, including financial data analysis, because the "true" multifractal effect should be clearly separated from the so called "multifractal noise" resulting from the finite data length. Examples from finance in this context are given. The provided formulas may help to decide whether one deals with the signal of real multifractal origin or not and make further step in analysis of the so called spurious or corrupted multifractality discussed in literature.
Źródło:
Acta Physica Polonica A; 2012, 121, 2B; B-34-B-39
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bands, Bonds, and Polarizations in Nitrides - from Electronic Orbitals to Electronic Devices
Autorzy:
Majewski, J. A.
Zandler, G.
Vogl, P.
Powiązania:
https://bibliotekanauki.pl/articles/2027476.pdf
Data publikacji:
2001-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Kp
77.65.Ly
Opis:
A key property of the nitrides is the fact that they possess large spontaneous and piezoelectric polarization fields that allow a significant tailoring of the carrier dynamics and optical properties of nitride devices. In this paper, based on first-principles calculations of structural and electronic properties of bulk nitrides and their heterostructure, we investigate the potential of this novel material class for modern device applications by performing self-consistent Monte Carlo simulations. Our studies reveal that the nitride based electronic devices have characteristics that predispose them for high power and high frequency applications. We demonstrate also that transistor characteristics are favorably influenced by the internal polarization induced electric fields.
Źródło:
Acta Physica Polonica A; 2001, 100, 2; 249-260
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Route to Prepare Magnetic Material $Co_3V_2O_8$ and Structural Characterization
Autorzy:
Celik, G.
Kurtulus, F.
Guler, H.
Powiązania:
https://bibliotekanauki.pl/articles/1491310.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.-m
32.30.Rj
33.20.Ea
61.43.Gt
61.66.Fn
65.40.-b
75.47.Lx
81.40.Gh
82.33.Pt
84.40.-x
Opis:
$Co_3V_2O_8$ is a member of kagomé staircase oxides, represented by general formula $M_3V_2O_8$ (M = Ni, Co, Mn). It attracted great attention due to strong magnetic anisotropy, magnetic phase transition, genuine macroscopic quantum effects, strong quantum fluctuations, low-temperature ferroelectricity, field-induced magnetic transitions, complicated phase diagram and displays long-range magnetic order because of geometrical frustration. Different routes to prepare the frustrated magnetic material was reported such as floating zone technique and conventional high temperature method. $Co_3V_2O_8$ (International Centre for Diffraction Data (ICDD): 16-675) was synthesized with $Co_3O_4$ (ICDD: 80-1536) as binary phase by microwave assisted preparation using $Co(NO_3)_2 ·6H_2O$ and $NH_4VO_3$. The synthesized material was characterization by powder X-ray diffraction, the Fourier transform infrared spectroscopy, and thermogravimetric-differential thermal analysis.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 203-204
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetics and Mechanical Studies of Melaminium bis(trichloroacetate) dihydrate
Autorzy:
Kanagathara, N.
Marchewka, M.
Gunasekaran, S.
Anbalagan, G.
Powiązania:
https://bibliotekanauki.pl/articles/1205304.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.20.Pm
65.40.-b
82.20.-w
62.20.Qp
83.50.-v
Opis:
The thermal decomposition kinetics of melaminium bis(trichloroacetate) dihydrate (MTCA) has been studied by thermogravimetry and derivative thermogravimetry techniques using non-isothermal experiments at three different heating rates 10, 15, and 20°C $\text{min}^{-1}$. Non-isothermal studies of MTCA revealed that the decomposition occurs in three stages involving dehydration and decomposition. The apparent activation energy $(E_{a})$ and the pre-exponential factor (ln A) of each stage of thermal decomposition at various linear heating rates are calculated using Flynn-Wall, Friedman, Kissinger, and Kim-Park method. A significant variation of effective activation energy $(E_{a})$ with conversion $(α)$ indicates that the process is kinetically complex. The linear relationship between the A and $E_{a}$ values is well established (compensation effect). Isothermal kinetics of thermal decomposition of MTCA was found to obey Avrami-Erofeev's (A4) and power law (P3) equations. In addition to the above, mechanical properties have been estimated by Vicker's microhardness test for the grown crystal.
Źródło:
Acta Physica Polonica A; 2014, 126, 3; 827-832
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multifractality of Nonlinear Transformations with Application in Finances
Autorzy:
Grech, D.
Pamuła, G.
Powiązania:
https://bibliotekanauki.pl/articles/1400170.pdf
Data publikacji:
2013-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.Df
05.45.Tp
89.65.Gh
89.75.Da
89.75.-k
89.20.-a
05.40.-a
Opis:
We study the multifractal effects of nonlinear transformations of monofractal, stationary time series and apply the found results to measure the "true" unbiased multifractality generated only by multiscaling properties of initial (primary) data before transformations. A difference is stressed between "naive" observed multifractal effects calculated directly within detrended multifractal analysis as the spread Δh of the generalized Hurst exponents h(q) and the more reliable unbiased multifractality received after subtraction of residual bias effects generated by nonlinear transformations of initial data and coupled with finite size effects in time series. This property is investigated for volatile series of the real main world financial indices. A difference between multifractal properties of intraday and interday quotes is also pointed out in this context for the Warsaw Stock Exchange WIG index. Finally, based on the observed feature of real nonstationary data, a new measure of unbiased multifractality in signals is introduced. This measure comes from an analysis of the whole generalized Hurst exponent profile instead of looking just at its edge behavior $h^{±} ≡ h(q→ ±∞)$. Such an approach seems to be particularly useful when h(q) is not a monotonic function of the moment order q. Interesting examples with extreme events from finance are presented. They convince that an analysis directed only on investigation of the edges $h^{±}$ in multifractal spectrum may be misleading.
Źródło:
Acta Physica Polonica A; 2013, 123, 3; 529-537
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intense Pulsed Electron Beams Application οf Modified Materials
Autorzy:
Weisenburger, A.
An, W.
Engelko, V.
Heinzel, A.
Jianu, A.
Lang, F.
Mueller, G.
Zimmermann, F.
Powiązania:
https://bibliotekanauki.pl/articles/1807912.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
28.41.Qb
81.40.Pq
81.65.Kn
Opis:
Intense pulsed electron beams have been applied for surface modification of materials in our laboratory for several years. An improvement of properties like wear, corrosion and oxidation resistance was found. Three different modification modes can be distinguished: rapid melting and solidification, surface alloying of coatings into the bulk and surface fusing of coatings to the bulk. All three surface treatment processes were investigated using the GESA (Gepulste Elektronen Strahl Anlage) facilities having following parameters: accelerating voltage 80-400 kV; power-density 2-6 MW/$cm^{2}$; beam diameter 4-10 cm; pulse duration 4-250 μs. Such pulses applied on material surfaces lead to a change in microstructure and in the case of surface alloying also to a change in chemical composition. This paper will give an overview on applications in different fields of surface modified materials.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1053-1055
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic specific heat of anion-radical salt [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO at very low temperatures
Autorzy:
Šoltésová, D.
Čižmár, E.
Vasylets, G.
Starodub, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1053060.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.Ba
75.30.Et
75.30.Gw
Opis:
Thermodynamic studies of the anion-radical salt system [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO, where TCNQ is 7,7',8,8'-tetracyano-quinodimethane, are reported. The anion-radical salt systems based on TCNQ belong to a material class in which the arrangement of the anion-radical salt has considerable impact on the charge transfer and magnetic properties. The crystal structure of the studied compound consists of [Ni(bipy)₃]⁺² cations containing Ni⁺² ions and four types of crystallographically independent anion-radicals TCNQ^{·-} (A, B, C and D). These TCNQ^{·-} radicals form two different types of TCNQ^{·-} stacks (AABB and CCDD), where a strong exchange interaction is expected. The temperature dependence of the specific heat of a single crystal was studied in magnetic fields up to 5 T and in the temperature range from 0.4 K to 30 K. The temperature dependence of specific heat displays a broad Schottky-like maximum above 0.4 K. Using a single-ion approximation, the analysis of the temperature dependence of the specific heat below 10 K yields values for the anisotropy parameters, D/k_{B}=-1.95 K and E/k_{B}=0.3 K. These results suggest that the observed maximum in the specific heat originates from Ni⁺² ions while the exchange interaction between the transition metal ions and the TCNQ is negligible.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 925-927
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wear Behavior of Surface Treated X45MoCrV5-3-1 Tool Steel at Room and Elevated Temperatures
Autorzy:
Aktaş, G.
Polat, Ş.
Atapek, Ş.
Powiązania:
https://bibliotekanauki.pl/articles/1401330.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.65.-b
81.40.Pq
81.70.-q
Opis:
The aim of this study is to compare the wear behavior of X45MoCrV5-3-1 tool steel, used as die material in aluminum extrusion, after single treatment (CrN coating) and duplex treatment (nitriding and CrN coating). Gas nitriding and physical vapor deposition were used as processing techniques and wear tests were carried out at both room and elevated temperatures. A "ball-on-disc" type tribometer was used for room temperature tests, utilizing Al₂O₃ ball as counterpart. In order to simulate the wear conditions during extrusion, hot wear tests were carried out at 450°C using "block-on-cylinder" type tribometer against AA 6080 material. Worn surfaces were studied by microscopy to reveal the wear characteristics of treated steels. It was found that (i) duplex treated steel, having higher friction coefficient at room and elevated temperature, had higher wear resistance, (ii) at room temperature single treated steel exhibited higher volume loss than the duplex treated one, (iii) at elevated temperature duplex treated steel revealed a stable coating layer, whereas micro cracks were observed on the surface of the single treated steel.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1221-1224
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Singular Pretransitional Behavior of the Electric Field-Dependent Part of the Thermodynamic Quantities of Strongly Polar Mesogenic Liquids in the Isotropic Phase
Autorzy:
Jadżyn, J.
Déjardin, J.-L.
Czechowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047352.pdf
Data publikacji:
2007-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Md
65.40.Gr
77.22.Ch
Opis:
A new interpretation of the pretransitional temperature behavior of the static dielectric permittivity and its derivative in terms of the basic thermodynamic quantities: the internal energy, the entropy, and the Helmholtz free energy is presented. It was shown that in the case of strongly polar mesogenic compounds (as the homologous series of alkylcyanobiphenyls) the electric field-induced increments of both the internal energy and the entropy exhibit a critical-like temperature dependence in the vicinity of transition from the isotropic liquid to the nematic phase. As a most important pretransitional effect, it is shown that at a temperature of about 10 degrees before the phase transition, an electric field applied to the isotropic liquids induces an increase in the entropy (Δ S>0) instead of its decrease, as observed far from the phase transition or for the non-mesogenic dipolar liquids.
Źródło:
Acta Physica Polonica A; 2007, 111, 6; 877-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice Dynamics of Laser Excited Ferroelectric $BaTiO_3$
Autorzy:
Issenmann, D.
Schleef, S.
Ibrahimkutty, S.
Buth, G.
Baumbach, T.
Plech, A.
Beyer, M.
Demsar, J.
Powiązania:
https://bibliotekanauki.pl/articles/1489957.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.D-
61.05.cp
77.22.Ej
65.40.De
64.60.Cn
Opis:
We investigated the lattice dynamics of the prototypic ferroelectric barium titanate close to its ferroelectric-paraelectric phase transition aiming at a better understanding of the atomistic nature of the transition. The usage of time-resolved X-ray techniques allows to disentangle lattice motion and unit cell changes, which, in part, relate to the ferroelectric polarization. In the quasi-static case both the electrical and the laser excitation show a mean-field, simple thermal behaviour, while for time scales shorter than nanoseconds the impulsive nature of the excitation becomes visible.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 319-323
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of Elastic Waves in a Quasi-One-Dimensional Cavity: Theory and Experiment
Autorzy:
Báez, G.
Cobián-Suárez, M.
Martínez-Argüello, A.
Martínez-Mares, M.
Méndez-Sánchez, R.
Powiązania:
https://bibliotekanauki.pl/articles/1399047.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
46.40.Cd
62.30.+d
03.65.Nk
73.21.Fg
Opis:
We study the scattering of torsional waves through a quasi-one-dimensional cavity both from the experimental and theoretical points of view. The experiment consists of an elastic rod with square cross-section. In order to form a cavity, a notch at a certain distance of one end of the rod was grooved. To absorb the waves, at the other side of the rod, a wedge, covered by an absorbing foam, was machined. In the theoretical description, the scattering matrix S of the torsional waves was obtained. The distribution of S is given by Poisson's kernel. The theoretical predictions show an excellent agreement with the experimental results. This experiment corresponds, in quantum mechanics, to the scattering by a delta potential, in one dimension, located at a certain distance from an impenetrable wall.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 1069-1073
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Entropy Change Calculations for Pure Gd and a Ni-Mn-Cu-Ga Heusler Alloy: Constant Field vs. Constant Temperature Experiment
Autorzy:
Ferenc, J.
Kowalczyk, M.
Wróblewski, R.
Cieślak, G.
Sielicki, K.
Leonowicz, M.
Kulik, T.
Powiązania:
https://bibliotekanauki.pl/articles/1402338.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
65.40.gd
Opis:
The magnetocaloric effect may be assessed indirectly by expressing it as the change in magnetic entropy in varying magnetic field, H, as the function of temperature, T. Magnetization, M=f(T,H), may be experimentally acquired from a series of isothermal measurements with variable field, or from a series of constant field measurements with variable temperature. The accuracy of magnetic entropy calculation depends on the number of series in these experiments. The aim of this work is to determine how little data is sufficient to obtain accurate results of magnetic entropy change calculations, on the basis of real, magnetocaloric materials. Pure gadolinium and a Ni-Mn-Cu-Ga Heusler alloy were studied. For both materials, the magnetic entropy change and relative cooling power were calculated from both experiments, with the decreasing number of experimental data. For both materials, the constant field experiment with only 6 field values provided only a 5% error of calculations, as compared to the experiment with 100 field values. The Arrott plots were also drawn for constant field mode with 6 field values, easily indicating the order of transition. Comparison of the calculation results suggests that the constant field mode magnetization measurement may be more accurate and faster than isothermal mode.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 111-115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Behaviour of PrCo_{1-x}Fe_xO₃ Probed by X-ray Synchrotron Powder Diffraction and Impedance Spectroscopy Measurements
Autorzy:
Pekinchak, O.
Sugak, D.
Ubizskii, S.
Suhak, Yu.
Fritze, H.
Vasylechko, L.
Powiązania:
https://bibliotekanauki.pl/articles/1029711.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
61.05.cp
65.40.De
72.60.+g
Opis:
Crystal structure and transport properties of the mixed praseodymium cobaltites-ferrites PrCo_{1-x}Fe_xO₃ have been studied in the temperature range of 298-1173 K by a combination of in situ X-ray synchrotron powder diffraction and temperature dependent impedance spectroscopy measurements. In situ high temperature powder diffraction examination of PrCo_{1-x}Fe_xO₃ series revealed considerable anomalies in the lattice expansion which are especially pronounced for the cobalt-rich specimens. These anomalies, which are reflected in a sigmoidal dependence of the unit cell dimensions and in the considerable increase of the thermal expansion coefficients, are obviously associated with transitions of Co^{3+} ions from low spin to the higher spin states and the coupled metal-insulator transitions, occurring in in rare earth cobaltites at the elevated temperatures. Indeed, the temperature-dependent impedance measurements clearly prove the change of conductivity type from dielectric to the metallic behaviour in the mixed cobaltite-ferrites PrCo_{1-x}Fe_xO₃ at the elevated temperatures.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 798-801
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact Diagonalization Study of an Extended Hubbard Model for a Cubic Cluster at Quarter Filling
Autorzy:
Szałowski, K.
Balcerzak, T.
Jaščur, M.
Bobák, A.
Žukovič, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032794.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.-c
75.10.Lp
71.27.+a
65.80.-g
05.70.Ce
Opis:
In the paper the thermodynamics of a cubic cluster with 8 sites at quarter filling is characterized by means of exact diagonalization technique. Particular emphasis is put on the behaviour of such response functions as specific heat and magnetic susceptibility. The system is modelled with extended Hubbard model which includes electron hopping between both first and second nearest neighbours as well as Coulombic interactions, both on-site and between nearest-neighbour sites. The importance of hopping between second nearest neighbours and Coulombic interactions between nearest neighbours for the temperature dependences of thermodynamic response functions is analysed. In particular, the predictions of the Schottky model are compared with the calculations based on the full energy spectrum.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1012-1014
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Semiconductor Nanostructures with nextnano$\text{}^{3}$
Autorzy:
Birner, S.
Hackenbuchner, S.
Sabathil, M.
Zandler, G.
Majewski, J. A.
Andlauer, T.
Zibold, T.
Morschl, R.
Trellakis, A.
Vogl, P.
Powiązania:
https://bibliotekanauki.pl/articles/2046896.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Cd
73.21.Fg
73.61.Ey
77.65.Ly
85.30.Tv
73.40.Mr
Opis:
nextnano$\text{}^{3}$ is a simulation tool that aims at providing global insight into the basic physical properties of realistic three-dimensional mesoscopic semiconductor structures. It focuses on quantum mechanical properties such as the global electronic structure, optical properties, and the effects of electric and magnetic fields for virtually any geometry and combination of semiconducting materials. For the calculation of the carrier dynamics a drift-diffusion model based on a quantum-mechanically calculated density is employed. In this paper we present an overview of the capabilities of nextnano$\text{}^{3}$ and discuss some of the main equations that are implemented into the code. As examples, we first discuss the strain tensor components and the piezoelectric effect associated with a compressively strained InAs layer for different growth directions, secondly, we calculate self-consistently the quantum mechanical electron density of a Double Gate MOSFET, then we compare the intersubband transitions in a multi-quantum well structure that have been obtained with a single-band effective mass approach and with an 8-band k·p model, and finally, we calculate the energy spectrum of a structure in a uniform magnetic field.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 111-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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