Lattice Dynamics and Thermal Expansion of Ruthenium

1979 ◽  
Vol 34 (6) ◽  
pp. 724-730 ◽  
Author(s):  
R. Ramji Rao ◽  
J. V. S. S. Narayana Murthy
Keyword(s):  
Thermal Expansion ◽  
Distribution Function ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Temperature Variation ◽  
Frequency Distribution ◽  
Lattice Dynamics ◽  
Pressure Variation ◽  
Frequency Distribution Function ◽  
Lattice Specific Heat

Abstract The lattice dynamics, lattice specific heat and thermal expansion of ruthenium are worked out using the model of Srinivasan and Ramji Rao, based on Keating’s approach. A total number of 50,880 frequencies has been used in constructing the frequency distribution function. The anharmonic parameters are obtained from the data of Clendenen and Drickamer on the pressure variation of the lattice parameters of ruthenium. The Anderson-Grüneisen parameter δ is calculated using the theoretical TOE constants, and the temperature variation of the bulk modulus is explained using Anderson’s theory.

scholarly journals Thermodynamic Properties of La1-xSmxCoO3

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Rasna Thakur ◽  
N. K. Gaur
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Specific Heats ◽  
Lattice Specific Heat ◽  
Lattice Distortions ◽  
First Time ◽  
Rigid Ion Model

We have investigated the bulk modulus and thermal properties of La1-xSmxCoO3 (0≤x≤0.2) at temperatures 1 K≤T≤300 K probably for the first time by incorporating the effect of lattice distortions using the modified rigid ion model (MRIM). The calculated specific heat, thermal expansion, bulk modulus, and other thermal properties reproduce well with the available experimental data, implying that MRIM represents properly the nature of the pure and doped cobaltate. The specific heats are found to increase with temperature and decrease with concentration (x) for the present. The increase in Debye temperature (θD) indicates an anomalous softening of the lattice specific heat because increase in T3-term in the specific heat occurs with the decrease of concentration (x).

Lattice Dynamics and Thermal Expansion of Thulium

1979 ◽  
Vol 34 (2) ◽  
pp. 200-206 ◽  
Author(s):  
R. Ramji Rao ◽  
A. Rajput
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Lattice Dynamics ◽  
Earth Metal ◽  
Magnetic Ordering ◽  
Magnetic Contribution ◽  
Magnetic Entropy ◽  
Lattice Heat Capacity ◽  
Lattice Specific Heat ◽  
Lattice Heat

Abstract The lattice dynamics, lattice specific heat and thermal expansion of the rare-earth metal thulium are worked out applying a model based on Keating’s method. A frequency distribution function involving 50,880 frequencies has been employed. Using the calculated lattice heat capacity, the experimental Cp data of thulium are analysed to get the magnetic contribution to the specific heat in this metal. The energy of magnetic ordering and the magnetic entropy increase involved in the transition from the ordered antiferromagnetic phase to the disordered paramagnetic phase are evaluated. The lattice parameters and volume of thulium are also calculated as a function of hydrostatic pressure and compared with the experimental results

LATTICE DYNAMICS OF CALCIUM FLUORIDE: PART II. THERMAL EXPANSION OF CALCIUM FLUORIDE

1962 ◽  
Vol 40 (1) ◽  
pp. 91-97 ◽  
Author(s):  
S. Ganesan ◽  
R. Srinivasan
Keyword(s):  
Thermal Expansion ◽  
Elastic Constant ◽  
Specific Heat ◽  
Liquid Helium ◽  
Temperature Variation ◽  
Thermal Expansion Coefficient ◽  
Calcium Fluoride ◽  
Lattice Dynamics ◽  
Helium Temperature ◽  
Good Agreement

With the model which explained the specific heat, the thermal expansion of calcium fluoride is calculated. Using the data on the temperature variation of the Raman line and the elastic constant C44, the Gruneisen parameter γi = −∂log ωj/∂log V is calculated as a function of ω for the optical and acoustic branches along [100], [111], and [110] directions. The thermal expansion coefficient is evaluated using Houston's method. The calculated values are in good agreement with the measured values of Valentiner and Wallott. Calculations reveal that γ0 = βV/χCv will increase with decreasing temperature, the rise starting in the liquid hydrogen region of temperature. The thermal expansion of this crystal can be measured up to liquid helium temperature to verify the result of these calculations.

scholarly journals THERMAL EXPANSION STUDY OF A UVAROVITE RICH GARNET

2007 ◽  
Vol 21 (11) ◽  
pp. 1915-1922 ◽  
Author(s):  
G. PARTHASARTHY ◽  
R. SRINIVASAN ◽  
G. D. MUKHERJEE ◽  
C. BANSAL ◽  
ASHOK CHATTERJEE
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Thermodynamic Parameters ◽  
Semiclassical Model ◽  
Lattice Specific Heat ◽  
First Time ◽  
Thermal Expansion Study

Thermal expansion measurements have been performed on a uvarovite rich garnet sample for the first time and compared with the expansion data on grossular and pyrope-rich garnets reported in the literature. A semiclassical model has been used to analyze the data and to obtain various thermodynamic parameters. Using these parameters, the lattice specific heat and the corresponding entropy have also been calculated.

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