Temperature Dependence of Second and Higher Order Elastic Constants of Orientationally Disordered (NH4I)x (KI)1-x Mixed Crystals

2014 ◽  
Vol 1047 ◽  
pp. 65-70 ◽  
Author(s):  
Alpana Tiwari
Keyword(s):  
Elastic Constants ◽  
Body Force ◽  
Coupling Effect ◽  
Second Order ◽  
Mixed Crystals ◽  
Elastic Behaviour ◽  
Coupling Term ◽  
Third Order ◽  
Third Order Elastic Constants ◽  
Three Body

We have incorporated the translational rotational (TR) coupling effects in the framework of three body force shell model (TSM) to develop an extended TSM (ETSM). This ETSM has been applied to reveal the second order elastic constants (C11, C12and C44) in the dilute regimes 0≤ x ≤ 0.50 as a function of temperature for 10K≤T≤300K. The anomalous elastic behaviour in C44below 100 K has been depicted well by ETSM results in the orientationally disordered (NH4I)x(KI)1-xmixed crystals. In order to present a visual comparison of the TR-coupling effect on second order elastic constants, we have evaluated the SOECs with and without TR coupling term in ETSM. Besides third order elastic constants have also been studied and discussed for concentration range 0≤x≤0.50 as a function of temperature for 10K≤T≤300K.

scholarly journals Third Order Pressure Derivative Elastic Properties of Alkali Cyanide

2020 ◽  
Vol 6 (10) ◽  
pp. 84-88
Author(s):  
Preeti Singh Bahadur
Keyword(s):  
Experimental Data ◽  
Elastic Constants ◽  
Body Force ◽  
Third Order ◽  
Pressure Derivative ◽  
Third Order Elastic Constants ◽  
Increasing Trend ◽  
Three Body ◽  
Increasing Temperature ◽  
Derivatives Of

In this paper we have evaluated the pressure derivatives of third order elastic constants in the CsCN material. An extended three body force shell model (ETSM), which incorporates the effects of translational– rotational (TR) coupling, three body interactions (TBI) and anharmonicity, has been applied. The pressure derivatives of TOECs, dc111/dp, dc112/dp, dc166/dp, dc111/dp dc123/dp and dc456/dp show increasing trend with increasing temperature. However their values could not be compared due to lack of experimental data.

THERMOELASTIC BEHAVIOUR OF FLUORITE SOLIDS USING THREE-BODY FORCE SHELL MODEL

1992 ◽  
Vol 06 (19) ◽  
pp. 3179-3188 ◽  
Author(s):  
S. S. BEDI ◽  
MAJOR SINGH ◽  
JASPAL SINGH
Keyword(s):  
Shell Model ◽  
Elastic Constants ◽  
Body Force ◽  
Thermal Phonon ◽  
Third Order ◽  
Third Order Elastic Constants ◽  
Three Body ◽  
Body Potential ◽  
Derivatives Of ◽  
Theoretical Results

The expressions for the second and third order elastic constants of fluorite lattice are derived using Lundqvist three-body potential incorporating thermal phonon pressure and inter-sublattice displacement through the shell model. Theoretically calculated values of the third order elastic constants are compared with the theoretical results of other workers and experiments. First order pressure derivatives of the second order elastic constants calculated using Thurston and Brugger relations for Ca 1-x Sr x F 2 and Sr 1-x Ba x F 2 are found to be in agreement with the experiment.

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