<span style="font-size: 22.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">Laser Raman spectroscopic studies of order-disorder phase transitions in Na_{<span style="font-size:17.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman","serif";mso-bidi-font-weight:bold">3</span>}<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">BaCl_{<span style="font-size:17.0pt; mso-bidi-font-size:10.0pt;font-family:"Times New Roman","serif";mso-bidi-font-weight: bold">5</span>}<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt; font-family:"Times New Roman","serif";mso-bidi-font-weight:bold">.2H₂O crystals </span></span></span>

Abstract

650-653<span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Laser Raman spectroscopic studies have been undenaken for Na<span style="font-size:17.0pt; mso-bidi-font-size:10.0pt;font-family:" times="" new="" roman","serif";mso-bidi-font-weight:="" bold"="">3<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt; font-family:" times="" new="" roman","serif";mso-bidi-font-weight:bold"="">BaCl5<span style="font-size:22.0pt; mso-bidi-font-size:15.0pt;font-family:" times="" new="" roman","serif";mso-bidi-font-weight:="" bold"="">.2H2O<span style="font-size:15.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif""=""> single crystals to study the structural phase transitions taking place in them through spectra- structure correlation. The spectral changes that take place in the low temperature phase below 267 K in this crystal in terms of intensity and bandwidth or the streching and librational modes show that these are indications or diffuse phase transitions associated with an order-disorder mechanism which involves the rotation or water molecules, freezing  below 267 K. No evidence of soft modes has been found for the crystal in the temperature region of<span style="font-size:13.5pt;mso-bidi-font-size:6.5pt; font-family:" arial","sans-serif""=""> t<span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">he presence studies. </span