Journal of Pure and Applied Ultrasonics

Jitendra Kumar ¹, S. K. Shrivastava ², Kailash ³

Affiliations
1 Department of Physics, Rajkiya Mahila Snatakottar Mahavidhyalaya, Banda-210001, IN
2 Department of Physics, Bundelkhand University, Jhansi-284001, IN
3 Department of Physics, B.N. P.G. College, Rath, Hamirpur-210431, IN

Abstract

The calcium oxide crystal possesses well developed fcc structure and is divalent in nature. Oxides and silicates make up the bulk of the Earth's mantle and crust, and thus it is important to predict their behavior for the study of seismic and volcanic activities. The second order elastic constants (SOECs) were computed using Coulomb and Born-Mayer potential in the temperature range 100-1000 K. The ultrasonic velocities were calculated using these values of second order elastic constants and density ρ. In this study temperature dependent velocities in calcium oxide have been calculated along <100>, <110> and <111> crystallographic directions and the results are presented graphically and discussed in depth.

Keywords

Micro Structural Properties, Seismic and Volcanic Activities, Acoustic Wave Velocities, Second Order Elastic Constants.

Full Text

   

Jitendra Kumar ¹, Virendra Kumar ², Kailash ³, S. K. Srivastava ⁴

Affiliations
1 Department of Physics, Govt. Girls P. G. College, Banda-210001, U.P., IN
2 D.A.V. Inter College, Banda-210001, U.P., IN
3 Department of Physics, BN PG College, Rath, Hamirpur-210431, U.P., IN
4 Department of Physics, Bundelkhand University, Jhansi-284128, U.P., IN

Abstract

The Calcium oxide crystal possesses well developed structure of the NaCl-type and is divalent in nature. Oxides and silicates make up the bulk of the Earth's mantle and crust, and thus it is important to predict their behaviour. The elastic energy density for a deformed crystal can be expanded as a power series of strains using Taylor's series expansion. One can get this expansion starting from nearest neighbour distance and hardness parameter utilizing Coulomb and Born-Mayer potentials for face centred cubic crystal symmetry. The coefficients of the quadratic, cubic and quartic terms are known as the second, third and fourth order elastic constants (SOECs, TOECs and FOECs) respectively. When the values of second and third order elastic constants and density for any material at a particular temperature are known; one may get ultrasonic velocities for longitudinal and shear waves in different crystallographic directions which give important information about its anharmonic properties.
The theory obtained is applied to get the higher order elastic constants for Calcium oxide crystal at different higher temperatures and the results obtained are presented graphically and discussed widely.

Full Text

   

Kailash ¹, K. M. Raju ¹, P. Yadav ¹

Affiliations
1 Department of Physics, Brahmanand Post-Graduate College, Rath, Hamirpur, UP, IN

Abstract

Milk is considered as an important food ingredient for a major sector of-population. Extensive study about milk quality has been reported in the recent past. Very little work has been done to study the quality of milk using ultrasonic techniques. This has motivated us to undertake the present study. In this paper, we have made detailed investigations of ultrasonic wave velocities in milk at different concentrations using single frequency ultrasonic interferometer.

Full Text

   

Kailash ¹, K. M. Raju ¹, Khare ¹

Affiliations
1 Department of Physics, Brahmanand Post-Graduate College, Rath, Hamirpur-210431, U.P., IN

Abstract

If the values of second order elastic constants and density at a particular temperature are known for any substance, one may obtain ultrasonic velocities for longitudinal and shear waves which give an important information about its anharmonic properties. For computing the second and third order elastic constants (SOECs & TOECs) at any temperature, a method have been developed, starting from nearest neighbour distance and hardness parameter assuming Coulomb and Born Mayer potentials for face centered cubic crystals. The anharmonic properties of lithium halides are evaluated at different temperatures (100 K to upto their melting points) using this formulation. The results obtained in present investigation are in reasonable agreement with other studies.

Full Text

   

Kailash ¹, K. M. Raju ¹, S. K. Shrivastava ², S. Kushwaha ³

Affiliations
1 Department of Physics, Brahmanand Post-Graduate College, Rath, Hamirpur-210431, UP, IN
2 Institute of Basic Sciences, Bundelkhand University, Jhansi-284128, UP, IN
3 Department of Physics, Pt. J.N. P.G. College, Banda-210001, UP, IN

Abstract

An effort has been made for obtaining the second order elastic constants of rocksalt structure solids starting from primary physical parameters viz. nearest neighbour and hardness parameter assuming long- and short-range potentials at an elevated temperature. When the values of the second order elastic constants are known for a crystal, many of the anharmonic properties of the crystal can be treated within the limit of the continuum approximation in quantitative manner. The ultrasonic velocity any crystal is directly related to their second order elastic constants (v-longitudianal=(C₁₁/d)^1/2, v-shear=(C₄₄/d)^1/2;d is density). In this study, second order elastic constants are computed upto their melting temperature for rocksalt structure solids, which are alkali cyanides, sodium and potassium halides. The results thus obtained are compared with experimental data and found in well agreement with present values.

Full Text