Study of molecular dynamics and phase transitions in trimethylammonium trichlorogermanate using $^1H$ NMR and DSC measurements

Mallikarjunaiah, KJ and Ramesh, KP and Damle, R (2007) Study of molecular dynamics and phase transitions in trimethylammonium trichlorogermanate using $^1H$ NMR and DSC measurements. In: Physica status solidi, 244 (10). pp. 3809-3816.

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Abstract

$(CH_3)_3NHGeCl_3$ is prepared, characterized and studied by $^1H$ NMR and differential scanning calorimetry to understand the molecular dynamics and phase transitions. The proton spin lattice relaxation time $(T_1)$ is measured at 20.53 MHz in the temperature range 391-5.2 K employing a home-made pulsed NMR spectrometer. The $T_1$ results show that $(CH_3)_3NHGeCl_3$ undergoes several phase transitions in the temperature range 391-50 K. Both $T_1$ data and DSC thermograms support the occurrence of phase transitions at 272 K and around 323 K. $T_1$ data are analyzed in three temperature regions using standard models. The $T_1$ variations in the intermediate temperature region 272-100 K are attributed to the hindered reorientations of symmetric groups $(CH_3$ and $(CH_3)_3NH)$. A broad asymmetric $T_1$ minimum in the temperature region 45-20 K is attributed to quantum rotational tunneling of the methyl groups.

Item Type:	Journal Article
Publication:	Physica status solidi
Publisher:	John Wiley & Sons, Inc.
Additional Information:	Copyright of this article belongs to John Wiley & Sons, Inc.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	28 Jul 2008
Last Modified:	19 Sep 2010 04:48
URI:	http://eprints.iisc.ac.in/id/eprint/15273

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