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1
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Total Crystal Energy and Heat of Solution of Alkali Based Binary Alloys

100%
Gajjar P., Thakore B., Jani A.
Acta Physica Polonica A
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2001
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vol. 99
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issue 5
565-578
EN
A detailed study of the total crystal energy and heat of solution of ten alkali based alloys is made within the framework of the second order perturbation theory and employing the pseudo alloy atom model. Three different forms of the local field correction functions, viz. Harrison, Taylor, and Ichimaru and Utsumi, are used to incorporate the exchange and correlation effects while computing the band structure part of the total energy. Reasonable agreement with the experimental values of the total energy of pure components is found (corresponding to the concentration factor x=0 or 1). It is observed that for all the systems, for small impurity concentration factors, the alloys form very good homogeneous solid solutions. Also the interaction parameter Δ E/x(1-x) does not depend on x, whenever the difference in the atomic sizes of the two components making up the alloy is small.
2
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Analytic Equation of State and Thermodynamic Properties, for α-, β-, and γ-Si₃N₄ Based on Analytic Mean Field Approach

80%
Wang L., Sun J., Yang W., Tian R.
Acta Physica Polonica A
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2008
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vol. 114
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issue 4
807-818
EN
The analytic mean field potential approach is applied to α-, β-, and γ-Si₃N₄. The analytic expressions for the Helmholtz free energy, internal energy, and equation of state were derived. The formalism for the case of the Morse potential is used in this work. Its six potential parameters are determined through fitting the compression experimental data of α-, β-, and γ-Si₃N₄. The calculated compression curves of α-, β-, and γ-Si₃N₄ are in good agreement with the available experimental data. This suggests that the analytic mean field potential approach is a very useful approach to study the thermodynamic properties of Si₃N₄. Furthermore, we predict the variation of the free energy and internal energy with the molar volume at several higher temperatures and calculate the temperature dependence of the molar volume, bulk modulus, thermal expansion coefficient and isochoric heat capacity at zero pressure.
3
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The Semiempirical Method for Finding Thermal Characteristics of Simple Crystals

80%
Scharoch M.
Acta Physica Polonica A
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2004
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vol. 106
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issue 4
487-495
EN
A method for ab initio (using density functional theory) study of thermal properties of crystalline solids, based on the quasiharmonic approximation, is briefly summarized. On that basis the semiempirical method is proposed which combines the ab initio calculation of the static total energy with the Einstein model of crystal vibration. The Murnaghan equation of states is used as an analytical model for the static total energy. An exponential form of the phonon energy versus volume dependence is introduced which was proved to perform very well. Two parameters appearing in the model are found by fitting to easily available experimental data (tabular or measured). The method then provides thermodynamic characteristics in a large range of temperatures and pressures. On the other hand, the corrections due to the zero-point vibration are provided to some first principles results, like lattice parameters or bulk modulus. An interesting outcome of the model is the pressure dependence of the overheating temperature, for relatively low pressures. Tests performed on the example of fcc aluminum show remarkably good agreement of the results with experimental data. Therefore the method offers a handy tool for fast analysis of thermodynamics of simple crystalline systems, omitting the first principles evaluation of the phonon energies.
4
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Study of Order Parameters Coupling in Uniaxial Ferroelectrics on the Basis of Pyroelectric and Dilatometric Measurements

80%
Gałązka M., Zieliński P.
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issue 4
566-569
EN
A method is devised of extracting the explicit form of the coupling between the primary and secondary order parameters with the use of experimental data and respecting classical and non-classical values of the effective critical exponents. The corresponding equation of state stems from the Ising model on a compressible lattice treated within the mean field approximation supplemented with terms ascertaining scaling invariance in the vicinity of the critical point. The theory is exemplified by the molecular ferroelectric crystals (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} (MAPCB) and (CH_{3}NH_{3})_{5}Bi_{2}Br_{11} (MAPBB).
5
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Scattering Properties of Argon Gas in the Temperature Range 87.3-120 K

80%
Al-Maaitah I., Joudeh B., Sandouqa A., Ghassib H.
Acta Physica Polonica A
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2016
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vol. 129
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issue 6
1131-1140
EN
A theoretical model, based on the Galitskii-Migdal-Feynman formalism, is introduced for determining the scattering properties of argon gas, especially the "effective" total, viscosity and average cross-sections. The effective phase shifts are used to compute the quantum second virial coefficient in the temperature range 87.3-120 K. The sole input is the Hartree-Fock dispersion (HFD-B3) potential. The thermophysical properties of the gas are then calculated. The results are in good agreement with experimental data.
6
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Nonclassical Critical Behaviour and Low Temperature Anomalies in Ferroelectric DMACA as Described by Many-Sublattice Model

80%
Gałązka M., Zieliński P.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
1013-1019
EN
A model based on the crystallographic data on dimethylammonium nonachlorodiantimonate (DMACA) is constructed. Gradual orientational ordering of three inequivalent sublattices of the dimethylammonium cations is shown to be at the origin of the anomalous behaviour of the spontaneous polarisation in this material. A quantitative comparison with the experimental data reveals a temperature dependence of a coupling between two sublattices and a strong deformability of the underlying structure.
7
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Some Elastic Properties and Phase Transitions in Some Alkali Halides Using Interatomic Potential Model

80%
Yazar H.
Acta Physica Polonica A
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2006
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vol. 109
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issue 6
743-751
EN
We have predicted the phase transition pressure in some alkali halides using an interatomic potential approach based on rigid ion model. This potential form represents the composite form of the inverse power dependence and exponential dependence of the repulsive energy on interionic distance. Some thermoelastic properties such as second order elastic constants have been calculated using the same potential. The phase transition pressures (28.69 and 2.4 GPa) obtained by us for two alkali halides (NaCl and KCl) are in closer agreement with their corresponding experimental data (29.0 and 2.0 GPa). This approach is promising with respect to prediction of the phase transition pressure of other alkali halides as well.
8
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Gas Sensing Properties of Carbon Nanotubes Modified with Calixarene Molecules Measured by QCM Techniques

61%
Mermer Ö., Okur S., Sümer F., Özbek C., Sayın S., Yılmaz M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
240-242
EN
This study focuses on the characterization and optimization of calixarene modified carbon nanotube thin films for gas detection. Calixarene molecules were synthesized individually by considering their functional groups to attract the gas. Calixarene modified carbon nanotube based sensors were fabricated using drop-casting method on a quartz crystal microbalance gold electrode. Carbon monoxide, carbondioxide, oxygen and dry air were used as active gases for adsorption process, while high-purity nitrogen gas was used for desorption process. The selectivity and sensitivity of calixarene modified carbon nanotube are investigated in detail. Our experimental results show that functional calixarene modified carbon nanotube coated quartz crystal microbalance sensors are very sensitive and selective to gas of CO_2 at room temperature operation.
9
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Study of a Mixed Hadronic-QGP System with Massive Particles

61%
Ghenam L., El Djoudi A.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-341-B-343
EN
We consider a mixed system of hadronic and quark-gluon plasma (QGP) phases in a finite volume, and use a phenomenological approach with two phases matter equations of state to study the occurring deconfinement phase transition with varying temperature and/or chemical potential. We take into account massive particles in both phases, and calculate several physical quantities describing well the system at the phase transition. We probe the behaviour of these quantities, by examining their variations with temperature and volume at fixed chemical potential, as well as with chemical potential and volume at fixed temperature, in three dimensional plots, and obtain the finite size effects on the deconfinement phase transition.
10
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Odor Adsorption Kinetics on Modified Textile Materials Using Quartz Microbalance Technique

61%
Sarıışık M., Okur S., Asma Ş.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
243-246
EN
In this study, a functional product with aromatic oil and vitamins for use at aromatherapy and spa centers or personal care has been designed to improve life quality of users by using multifunctional products with good odor, moisturizing, relaxation, anti-aging effects. For this purpose, commercial berry berry oil was capsulated in β-cyclodextrin, and then applied to 100% cotton towel fabric. Quartz crystal microbalance sensors were used to investigate odor adsorption kinetics on modified textile materials for the first time. The frequency responses vs. time plot shows clear linear step responses to the change in the concentration of odor molecules coming from the container filled with berry berry applied textile. The results also reveal that TiO_2 coated quartz crystal microbalance sensors can be used as e-nose to sense odor from textile coated with berry berry oil containing β-cyclodextrin capsules.
11
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Electrical Characterization of Interdigitated Humidity Sensors Based on CNT Modified Calixarene Molecules

61%
Özbek C., Culcular E., Okur S., Yılmaz M., Kurt M.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
461-463
EN
In this study, we report on the optimization and characterization of chloroform soluble calix[4]arene derivative as a humidity sensor based on electrical properties. Due to the fact that calix[4]arene molecules are nonconductive, we modified the calix[4]arene molecules with carbon nanotubes with electrostatic bond in order to increase the conductance of calix[4]arene molecule (5,11,17,23-tetra-ter-butyl-25,27-dehydrazinamidcarbonilmetoxy-26,28-dehydroxy-kalix[4]aren). Using photolithography technique, we fabricated interdigitated gold electrodes with 3 micrometers separation to investigate the electrical properties of carbon nanotubes modified calix[4]arene molecule where we used dropcast method to form a thin film of carbon nanotubes modified calix[4]arene molecule on the gold electrodes. Our reproducible experimental results indicated that the chloroform soluble carbon nanotubes modified calix[4]arene films have great potential for humidity sensing applications at room temperature operations.
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