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1

The Melting and the Debye Temperature of for BCC and FCC Metals Under Pressure: A Calculation from the Statistical Moment Method

Hoc Nguyen Quang, Tinh Bui Duc, Hien Nguyen Duc

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1227--1234

EN

We build the melting theory and the theory of the Debye temperature for defective and perfect cubic metals mainly based on the statistical moment method. Our theoretical results are applied to metals Ni, Pd and Pt. Our calculations of melting temperatures agree well with experiments and other calculations. Our other calculations are highly reliable.

2

Temperature dependence of the energy band gap of CuSi2P3 semiconductor using PSOPW method

Abdullah T. G., Sami S. A., Omar M. S.

Materials Science Poland

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2018

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Vol. 36, No. 4

553--562

EN

Theoretical formalism based on the orthogonalized plane wave method supplemented by a potential scaling scheme was used to predict the temperature dependence of energy gap of CuSi2P3 semiconductor. A computer code in Pascal was used to perform the variation of fundamental energy gap with temperature in the range of 150 K to 800 K. The dependence of energy gap on temperature for lattice dilation contribution, lattice vibration contribution and total temperature effect were performed separately. The results revealed that, as temperature increases, the top of the valence band and the bottom of the conduction band increase, while the energy band gap decreases. Generally, at low temperatures, the energy gap varies slowly and exhibits a nonlinear dependence and approaches linearity as temperature increases. The calculated energy gap of CuSi2P3 at T = 300 K is 0.4155 eV. The temperature coefficients in the linear region due to lattice dilation contribution, lattice vibration contribution and total temperature effect were calculated as –1.101 × 10−5 eV/K, –1.637 × 10−4 eV/K and –1.7523 × 10−4 eV/K, respectively. Also, the ratio of temperature coefficient of the energy gap due to LV contribution to its value and LD contribution in the linear region is equal to 14.868. That ratio is compared to those of CuGe2P3 and III-V compounds, where those of the latter show a systematic change with Eg. Moreover, the Eg of all the compounds shows a quadratic dependence on the inverse of mean bond length.

3

Ab-initio studies of thermal and superconducting properties of HfX2 alloys (X = Tc, Re, and Os)

Sathyakumari V S, Sankar S, Mahalakshmi K

Materials Science Poland

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2014

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Vol. 32, No. 3

324--330

EN

A systematic study of thermal properties such as the Debye temperature, specific heat coefficient, Gruneisen constant, electron-phonon coupling constant and transition temperature have been carried out using the results of electronic band structure and related characteristics, for hafnium superconducting alloys, namely, HfTc2, HfRe2 and HfOs2. Computation of the electronic band structure and associated properties has been carried out using the tight-binding-linear-muffin-tin-orbital (TBLMTO) method within atomic sphere approximation (ASA). The calculated values have been compared with the available results of literature data.

4

Structure and Ultrasonic Properties of Vanadium Tellurite Glasses Containing Copper Oxide

Abd El-Aal N. S., Afifi H. A.

Archives of Acoustics

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2009

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Vol. 34, No. 4

641-654

EN

The elastic properties of vanadium tellurite glasses, 65TeO2-(35-x) V2O5-xCuO, with different compositions of Copper (x = 7.5 to 17.5 mol% in steps of 2.5 mol%) have been studied at room temperature (300 K). The ultrasonic velocity measurements have been made, using a transducer having resonating frequency of 4 MHz (both longitudinal and shear). The density, molar volume, and ultrasonic velocities show interesting features, which are used to explore the structural changes in the network. Elastic moduli, Poisson ratio, crosslink density, Microhardnes, and Debye temperature of the glasses have been determined using the experimental data. The composition dependence of the elastic properties explores useful information about the physical properties of the vanadium tellurite glasses doped with Copper. Quantitative analysis has been carried out in order to obtain more information about the structure of the glass under the study, based on bond compression model and the Makishima & Mackenzie model. The observed results through ultrasonic nondestructive evaluation, investigate the structural changes and mechanical properties of the glass.