Laser Raman spectra of mixed crystals of [(NH4)1-xKx]2SO4

Srinivasan, V. ; Subramanian, C. K. (1983) Laser Raman spectra of mixed crystals of [(NH4)1-xKx]2SO4 Pramana - Journal of Physics, 21 (1). pp. 41-50. ISSN 0304-4289

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The Raman spectra of mixed crystals of [(NH4)1-xKx]2SO4 in the region 50–3400 cm-1 at 293 K and below 223 K have been reported. At room temperature 293 K, as the concentration of K+ ion increases in the crystal up to 50%, the frequencies of the totally symmetric vibrations of SO42- and NH4+ ions increase and thereafter the frequency of SO42- vibration decreases and attains the value in K2SO4. This change in frequency up to 50% of potassium concentration is due to the breaking of hydrogen bonds of the type N-H...O. The behaviour of Raman intensities of Ag1) mode of SO42- for various concentrations (x=0, 0·03, 0·11, 0·5, 0·85) suggest that the phase transition changes from first order type to one of second order. The phase transition in mixed crystals of [(NH4)1-xKx]2SO4 can be a cooperative phenomenon arising from a coupling between (NH4)+ ions through hydrogen bonds with the distorted SO42- ions in the low temperature phase.

Item Type:Article
Source:Copyright of this article belongs to Pramana - Journal of Physics.
Keywords:Laser Raman Spectra; Mixed Crystals; Hydrogen Bond; Infrared Spectra; Order-disorder
ID Code:32320
Deposited On:29 Jun 2011 13:23
Last Modified:17 May 2016 15:07

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