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).

THE ELASTIC AND THERMODYNAMIC PROPERTIES OF Lu DOPED ScVO3

2012 ◽  
Vol 26 (31) ◽  
pp. 1250190
Author(s):  
ATAHAR PARVEEN ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Phase Transitions ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Structural Phase ◽  
Magnetic Ordering ◽  
Structural Phase Transitions ◽  
Lattice Distortions ◽  
Rigid Ion Model

We have investigated the elastic, cohesive and thermal properties of (Lu, Sc) VO 3 and Sc 1-x Lu x VO 3(0.6 ≤ x ≤ 0.9) perovskites by means of a modified rigid ion model (MRIM). The variation of specific heat is determined following the temperature driven structural phase transitions. Also, the effect of lattice distortions on the elastic and thermal properties of the present pure and doped vanadates has been studied by an atomistic approach. The calculated bulk modulus (BT), reststrahlen frequency (ν0), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ) reproduce well with the corresponding experimental data. The specific heat results can further be improved by including the magnetic ordering contributions to the specific heat.

LOW TEMPERATURE SPECIFIC HEAT OF INTERMETALLICS (Ti/Be)B2

2007 ◽  
Vol 21 (14) ◽  
pp. 885-891 ◽  
Author(s):  
NUPINDER KAUR ◽  
N. K. GAUR ◽  
R. K. SINGH
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Low Temperature ◽  
Specific Heat ◽  
Debye Temperature ◽  
Cohesive Energy ◽  
Specific Heats ◽  
Molecular Force ◽  
Low Temperature Specific Heat ◽  
Rigid Ion Model

We have applied the Rigid Ion Model (RIM) to study the cohesive and thermal properties of binary intermetallic BeB 2 and TiB 2. The paper reports the calculated results on cohesive energy (ϕ), compressibility (β), molecular force constant (f), Restrahalen frequency (ν0), Debye temperature (Θ D ) and Gruneisen parameter (γ) for the temperature range 50 K ≤ T ≤ 300 K and the effect of van der Waal interaction on these properties are also shown. Our results on Debye temperature are closer to the experimental data. In addition, we have computed the specific heats for BeB 2 and TiB 2 and compared them with the available experimental data.

ELASTIC AND THERMAL PROPERTIES OF Sr1-xCaxRuO3

2013 ◽  
Vol 27 (17) ◽  
pp. 1350054 ◽  
Author(s):  
RASNA THAKUR ◽  
RAJESH K. THAKUR ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Specific Heat ◽  
Debye Temperature ◽  
Cohesive Energy ◽  
Molecular Force ◽  
Almost All ◽  
Good Agreement ◽  
Rigid Ion Model

We have investigated the elastic and thermal properties of Sr 1-x Ca x RuO 3(0≤x ≤1) perovskite using a modified rigid ion model (MRIM). The trend of variation of our computed specific heat in the temperature range 1 K ≤ T ≤ 1000 K are in good agreement with corresponding experimental data for almost all the compositions (x). The specific heat found to increase with temperature from 1 K to 300 K, while they decrease with concentration (x) for these perovskite ruthenates. Besides, we have reported the thermal properties, like thermal expansion (α), molecular force constant (f), Reststrahlen frequency (υ), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ).

PHONON DEPENDENCE ON THERMAL PROPERTIES OF RGaO3(R = La, Ce, Nd, Pr, Sm, Gd)

2012 ◽  
Vol 01 (01) ◽  
pp. 1250006
Author(s):  
ATAHAR PARVEEN ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Rare Earth ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Debye Temperature ◽  
Van Der Waals Interactions ◽  
Cohesive Properties ◽  
Rigid Ion Model

We have systematically investigated the effect of phonons on elastic, thermal and cohesive properties for rare earth gallates RGaO3 (R = La, Ce, Nd, Pr, Sm, Gd) by means of a Rigid Ion Model after modifying its framework to incorporate the van der Waals interactions. Besides that, we have calculated the temperature dependence of the specific heat for the present orthogallates. The results on bulk modulus, Debye temperature and specific heat reproduce well with the available experimental data.

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.

SPECIFIC HEAT OF Tb0.5Sr0.5CoO3 CERAMICS

2013 ◽  
Vol 22 ◽  
pp. 391-396
Author(s):  
RASNA THAKUR ◽  
RAJESH K. THAKUR ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Debye Temperature ◽  
Cohesive Energy ◽  
Grüneisen Parameter ◽  
Temperature Range ◽  
Proper Interpretation ◽  
Rigid Ion Model

We have investigated the thermal and allied properties of Tb0.5Sr0.5CoO3 for the temperature range 1K≤T≤300K using the Modified Rigid Ion Model (MRIM). The calculated bulk modulus, specific heat, and other thermodynamic properties obtained from MRIM have presented proper interpretation of the experimental data, for Sr ions doped TbCoO3 . In addition, the results on the cohesive energy (φ), Debye temperature (θD) and Gruneisen parameter (γ) are also discussed.

LOW TEMPERATURE SPECIFIC HEAT OF (KBr)1-x(KCN)x MIXED CRYSTAL

2003 ◽  
Vol 17 (26) ◽  
pp. 1391-1398 ◽  
Author(s):  
N. K. GAUR ◽  
NUPINDER KAUR ◽  
MANIK MANAKE ◽  
JYOTSNA GALGALE ◽  
R. K. SINGH
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Specific Heat ◽  
Mixed Crystal ◽  
Body Force ◽  
Molecular Force ◽  
Low Temperature Specific Heat ◽  
Three Body ◽  
First Time ◽  
Good Agreement

We have investigated the cohesive and thermodynamic properties of ( KBr )1-x( KCN )x using an extended three-body force shell model (ETSM), which has been found to be adequately suitable for the description of orientationally disordered mixed cyanide-halide crystals. The specific heat of ( KBr )1-x( KCN )x for compositions (x=0.53, 0.65, 0.73, 0.84 and 0.93) at temperature 10 K ≤T≤150 K have been computed using the ETSM for the first time. The paper also reports the calculated results on Debye temperature (Θ D ), cohesive energy (Φ), compressibility (β), molecular force constant (f) and Restrahlen frequency (ν0) of ( KBr )1-x( KCN )x. The results on specific heat and some other thermal properties are in good agreement with their available experimental data.

Effect of Cd Doping on Mechanical Properties of SrCoO3

2014 ◽  
Vol 975 ◽  
pp. 163-167 ◽  
Author(s):  
N.K. Gaur ◽  
Rasna Thakur ◽  
Rajesh K. Thakur ◽  
A.K. Nigam
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Anisotropy Parameter ◽  
Cd Doping ◽  
First Time ◽  
Rigid Ion Model

We have investigated the elastic and thermal properties of Sr1-xCdxCoO3 (0=x=0.1) probably for the first time by means of modified rigid ion model (MRIM). In this paper, we present the second order elastic constants (SOECs) and other elastic properties like Bulk modulus (B), Young's modulus (Y), Shear modulus (G), ̠̹̿̓̓̿̾˷̓˰̱̹͂̈́̿˰˸σ˹˼˰̵̜̱̽˷̓˰̵̵̱̱̀͂̽̈́͂˰˸m, l), transverse, longitudinal, ˰̵̷̵̱̱͆͂˰̵͇̱͆˰̵̼̳̹͉͆̿̈́˰˰˸υt, υl˼˰υm) and Anisotropy parameter (A). Here, the SOECs for Sr1-xCdxCoO3 compounds are positive and satisfy the generalized criteria for mechanically stable crystals: (C11-C12) > 0, (C11+2C12) > 0 and C44 > 0 which confirm that Sr1-xCdxCoO3 (0=x=0.1) belong to metallically bonding materials.

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 Thermal Properties of Yttrium Aluminum Garnett From Molecular Dynamics Simulations

2011 ◽  
Author(s):  
Majid S. al-Dosari ◽  
D. G. Walker
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Specific Heat ◽  
Molecular Dynamics Simulations ◽  
Yttrium Aluminum Garnet ◽  
System Size ◽  
Yttrium Aluminum ◽  
Dynamics Simulations

Yttrium Aluminum Garnet (YAG, Y3Al5O12) and its varieties have applications in thermographic phosphors, lasing mediums, and thermal barriers. In this work, thermal properties of crystalline YAG where aluminum atoms are substituted with gallium atoms (Y3(Al1−xGax)5O12) are explored with molecular dynamics simulations. For YAG at 300K, the simulations gave values close to experimental values for constant-pressure specific heat, thermal expansion, and bulk thermal conductivity. For various values of x, the simulations predicted no change in thermal expansion, an increase in specific heat, and a decrease in thermal conductivity for x = 50%. Furthermore, the simulations predicted a decrease in thermal conductivity with decreasing system size.

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