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Author(s) |
Sharma, V. K.; Mitra, S.; Thakur, N.; Yusuf, S. M.; Juranyi, F.; Mukhopadhyay, R. (SSPD)
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Source |
Journal of Applied Physics, 2014. Vol. 116 (3): pp. 034909.1-034909.9 |
ABSTRACT
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Dynamics of crystal water in Prussian blue (PB), Fe(III)4[Fe(II)(CN)6]3.14H2O and its analogue Prussian green (PG), ferriferricynaide, Fe(III)4[Fe(III)(CN)6]4.16H2O
have been investigated using Quasielastic Neutron Scattering (QENS)
technique. PB and its analogue compounds are important materials for
their various interesting multifunctional properties. It is known that
crystal water plays a crucial role towards the multifunctional
properties of Prussian blue analogue compounds. Three structurally
distinguishable water molecules: (i) coordinated water molecules at
empty nitrogen sites, (ii) non-coordinated water molecules in the
spherical cavities, and (iii) at interstitial sites exist in PB. Here
spherical cavities are created due to the vacant sites of Fe(CN)6 units. However, PG does not have any such vacant N or Fe(CN)6
units, and only one kind of water molecules, exists only at
interstitial sites. QENS experiments have been carried out on both the
compounds in the temperature range of 260–360 K to elucidate the
dynamical behavior of different kinds of water molecules. Dynamics is
found to be much more pronounced in case of PB, compared to PG. A
detailed data analysis showed that localized translational diffusion
model could describe the observed data for both PB and PG systems. The
average diffusion coefficient is found to be much larger in the PB than
PG. The obtained domain of dynamics is found to be consistent with the
geometry of the structure of the two systems. Combining the data of the
two systems, a quantitative estimate of the dynamics, corresponding to
the water molecules at different locations is made. |
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