International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Special Issue: 09 | Sep -2017
p-ISSN: 2395-0072
www.irjet.net
One Day International Seminar on Materials Science & Technology (ISMST 2017) 4th August 2017 Organized by
Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India
Studies on the effect of Sodium Chloride on Ammonium Dihydrogen Phosphate Single Crystals M. R. Bindhu1, Beena.M.Amala2 1,2Department
of Physics, Nanjil Catholic College of Arts and Science, Nedumcode, Kaliyakavilai, Tamil Nadu, India. ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Single crystals of pure and 0.5 mol% sodium
chloride (NaCl) doped ammonium dihydrogen phosphate (ADP) were grown from aqueous solution by slow evaporation technique at room temperature. The grown crystals were characterized by powder X-ray diffraction (PXRD) and the lattice parameters were calculated. The functional groups present in the grown crystals were confirmed by FTIR studies. The optical transparency of the grown crystals was determined using UV-vis-NIR spectroscopic studies. The mechanical property of the crystals was found out by microhardness measurement. Key Words: ADP crystal, slow evaporation technique, PXRD, FTIR, UV-vis-NIR.
1.INTRODUCTION Ammonium dihydrogen phosphate with chemical formula NH4H2PO4, is a commercially available inorganic dielectric material. ADP has unique nonlinear optical, electro optical, piezo electric and antiferroelectric properties. ADP is widely used as the second, third and fourth harmonic generator for Nd: YAG and Nd: YLF lasers. ADP crystals are used for electro optical applications such as Q-switches for Nd: YAG, Nd: YLF, Ti: Sapphire and Alexandrite lasers as well as for acousto optical applications. Due to its interesting electrical and optical properties, structural phase transitions and ease of crystallization, it has been the subject of a wide variety of investigations for several decades. ADP crystallizes from aqueous solution in anhydrous form in the I space group [1,2]. The molecular weight and density of ADP at room temperature are 115.03 g and 1.803 g/cc. ADP crystal has tetramolecular unit cell having unitcell parameters a = b = 7.510 Å and c = 7.564 Å [3]. Determination of the permittivity ε at a frequency of 36 Gc/s is described, the values obtained are ε|| = 14.0 at 21 °C and ε⊥ = 57.1 at 21.5 °C, where ε|| and ε⊥ are the values of permittivity when the applied electric field is parallel with or perpendicular to the optical axis [4]. ADP crystal decomposes at 210 oC to orthophosphoric acid with the evolution of ammonia [5]. ADP is a widely used crystal in the field of optics due to its birefringence properties. ADP crystals are piezoelectric which is a property required in some active sonar transducers. Sodium chloride (NaCl) is an inorganic material soluble in water. NaCl exists as ions in solution. NaCl has © 2017, IRJET
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Impact Factor value: 6.171
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molar mass 58.44 g. It appears as a clear crystal with little or no odor. NaCl is chosen as the impurity in this work. With the aim of modifying ADP, in the present work, ADP is doped with sodium chloride (NaCl) and pure and 0.5 mol% NaCl doped ADP crystal have been grown and studied.
2. Experimental procedure 2.1 Crystal growth Single crystals of pure and NaCl doped ADP crystals have been grown by slow evaporation process at room temperature. Ammonium dihydrogen phosphate salt and NaCl salt (GR grade) from Merck and double distilled water were used throughout the work. ADP was doped with NaCl in ratio 1:0.05. The solution was stirred continuously for 2 hours using magnetic stirrer for homogenization. It was then filtered using Whatmann filter paper, and transferred to a 250 ml beaker. The beaker was porously sealed and kept in an undisturbed place for slow evaporation. The supersaturated solution for the formation of NaCl doped ADP crystal was prepared by dissolving required amount of NaCl along with ADP and the saturated solution transferred to another beaker and kept in an undisturbed place. Crystals of considerable size were harvested within 12- 13 days. All the harvested crystals were washed with distilled water and dried using filter paper. The grown crystals were found to be stable, colourless and transparent. The photographs of the grown crystals are shown in fig. 1a and1b. Pure ADP
Fig. 1a
0.5mol%NaCl doped ADP
Fig. 1b
Fig. 1 Photographs of pure and 0.5 mol% NaCl doped ADP
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