Journal of Pure and Applied Ultrasonics

N. Dharani Rajan ¹, S. Jayakumar ¹, S. Krishnan ¹, G. M. Rajesh ¹, Sylaja ², R. Sambasivam ³

Affiliations
1 Department of Physics, RKM Vivekananda College, Mylapore, Chennai-600004, IN
2 Department of Physics, D.G. Vaishnav College, Chennai-600106, IN
3 Department of Physics, Urumu Dhanalakshmi College, Trichy, Tiruchirappalli-620019, IN

Abstract

Single crystal of aluminum ammonium sulfate has been grown. Crystals are subjected to X-ray diffraction analysis and Acoustical studies. Acoustical studies are made before and after crystal growth formation. Acoustical parameters like acoustical impedance (Z), free length (L_f), compressibility (β), relaxation time (τ), attenuation (α), coefficient of absorption (α/f²) are determined from velocity, density and viscosity measurements. The crystal is formed at 0.453 gm/ml and interesting changes in physical and chemical properties takes place. The smaller value of Hardness refers to soft crystal. Surface morphology of the crystal grown was studied by scanning electron microscope (SEM). From the observation of fluorescence spectra the luminescence properties of planar single crystal of AAS is studied. XRD studies confirm crystal belongs to cubic system. The cell parameters are a = 24.56A°, b = 24.56A°, c = 24.56A°, α = β = γ = 90°°, volume 14815A⁰³.

Keywords

Crystal Growth, XRD, Micro Hardness Studies, Ultrasonic Studie, Aluminum Ammonium Sulfate.

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G. M. Rajesh ¹, S. Jayakumar ¹, N. Dharani Rajan ¹, S. Krishnan ¹, Sylaja ², R. Sambasivam ³, Subhash Kondowar ⁴, Vilas A. Tabhane ⁵

Affiliations
1 Department of Physics, RKM Vivekananda College, University of Madras, Chennai-600 004, IN
2 Department of Physics, D.G. Vaishnav College, Chennai-600 106, IN
3 Department of Physics, Urumu Dhanalakshmi College, Trichy-620 019, IN
4 Department of Physics, RTM Nagpur University, Nagpur-440 033, IN
5 Department of Physics, Savitribai Phule Pune University, Pune-411 007, IN

Abstract

Ultrasonic velocity has been estimated in crystals namely aluminum ammonium sulfate and thiourea in water. XRD analysis were carried out at the temperature 303K. Acoustical parameters, stability constant had been obtained for the single crystal aluminum ammonium sulfate and thiourea. Internal pressure, free volume and molar cohesive energy had been obtained for the crystal. From the XRD studies the crystal belongs to cubic structure.

Keywords

Ultrasonic Velocity, Aluminum Ammonium Sulfate, Thiourea.

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N. Dharani Rajan ¹, S. Jayakumar ², G.M. Rajesh ¹, S. Krishnan ¹, G.S. Gayathri ³, R. Sambasivam ⁴, M. Dhavamurthy ⁵, Anees Ahmed ⁶

Affiliations
1 Department of Physics, RKM Vivekananda College, Chennai-600004, IN
2 Department of Physics, RKM Vivekananda College, Chennai-600004
3 Department of Chemistry, S. A. Engineering College, Chennai-600077
4 Department of Physics, Urumu Dhanalakshmi College, Trichy-620019, IN
5 Department of Physics, NIT, Trichy-620019, IN
6 The New College, Chennai-600014, IN

Abstract

In recent research technology, NLO crystal plays the wide role in biological, pharmaceutical and optoelectronic fields. The present study involves bulk single crystal of materials used in both active and passive modes in order to produce devices directly on bulk grown slices of material, as substrates in epitaxial growth, are discussed respectively. Single-crystal material usually provides superior properties of polycrystalline or amorphous equivalents. The various bulk growth techniques are outlined, together with specific critical features and examples are given for the types of materials and their current typical sizes, grown by these techniques. The wide range of materials used in the current research were (NH4) Al(SO4)2, C2H6N3O2, C7H10N4O3 and (2CH6N3 +. C7H4O6S2- H2O). The grown crystals were subjected to x-ray diffraction analysis in order to find the lattice parameter and crystal structure. Structural analysis by single crystal XRD analysis reveals the crystals studied belongs to Cubic, Tetragonal and Orthorhombic systems. The second harmonic generation (SHG) efficiency of grown crystals is found. Dielectric constant, uv- vis studies, microhardness and elastic constant have been studied to prove the optical nature of the materials.

Keywords

NLO, Crystal Structure, Growth From Solutions, Single Crystal, XRD, SHG.

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G.M. Rajesh ¹, S. Jayakumar ¹, N. Dharani Rajan ¹, G.S. Gayathri ², R. Ravi ³

Affiliations
1 Department of Physics, RKM Vivekananda College, Mylapore, Chennai, IN
2 Department of Chemistry, S. A. Engineering College, Chennai, IN
3 Department of Chemistry, Govt Arts College, Thiruvannamalai, IN

Abstract

Ultrasonic velocity, density and viscosity of the aqueous PVA solutions are measured using the ultrasonic interferometer and Ostwald viscometer respectively at 303 K. The various concentrations of PVA with water are prepared. From the measured parameters, thermo acoustical parameters like adiabatic compressibility, molecular free length, specific acoustic impedance, viscous relaxation time, absorption coefficient, molar volume, free volume and internal pressure are calculated. The magnitude of these parameters shows intermolecular interaction between solute and solvent molecules. The stability constant is determined by Yoshida & Osawa method and Kannappan method which helps in understanding the stability of polymer - ion interactions in the binary mixture. Excess parameters have been calculated and discussed with respect to the type of interaction existing between unlike components. Frequency acoustic spectrum evidences the nature of intermolecular interaction in the system.

Keywords

PVA, Absorption Co-efficient, Stability Constant, Polymer - Ion Interactions.

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N. Dharani Rajan ¹, S. Jayakumar ¹, G.M. Rajesh ¹, R. Ravisankar ², G.S. Gayathri ³

Affiliations
1 Department of Physics, RKM Vivekananda College, Mylapore, Chennai-600 004, IN
2 Department of Physics, Govt. Arts College, Thiruvannamalai, IN
3 Department of Chemistry, S. A. Engineering College, Chennai, IN

Abstract

Polyvinyl pyrolidine is a non ionic polymer and it is a protein acceptor. PVP is soluble in water and other polar solvents. Its chemical formula is. PVP is used as binder, stabilizer, adhesive, complexing agent and in resins. Ultrasonic velocity, viscosity and density studies on aqueous solutions of PVP of Molecular Weight 40,000 have been carried out. From the velocity, density and viscosity values, various Acoustical Parameters, specific acoustic impedance, adiabatic compressibility, intermolecular free length, viscous relaxation time attenuation factor, absorption coefficient, internal pressure and free volume have been computed. All these parameters have been discussed to throw light on the polymer solute solvent interaction. The stability constant k is obtained from Yoshida and Oswaa method and Kannappan method. The stability constant of polymer in solution, gives the stability and the nature of interaction. The frequency acoustic spectra (FAS) of ultrasonic waves is determined from low frequency to high frequency. From the frequency Acoustic Spectra the bandwidth of the aqueous polymer solution obtained is 3000 m/s. Lebowitz and Reiss have developed a formulation called scaled particle theory, which has been used to find out radial distribution function. The theory gives a relation between ultrasonic velocity and hard convex spherical molecules, which is used to calculate various parameters like specific heat capacity, packing density, molecular diameter and ultrasonic velocity. The radial distribution function and constant (K, A and B) is determined. These values are compared with standard values. Statistical analysis of ultrasonic velocity in the polymer solution shows the mean value is 1322 4 m/s. The standard deviation of velocity obtained is 42.60. The higher standard deviation the lesser will be the variation in the observation. PVP is amphiphilic in nature. The hydrophilic nature of PVP involves the presence of interaction between carbonyl group and polar solvent.

Keywords

Nonionic, stabilizer, stability constant, scaled particle theory.

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