Broad-Band Spectroscopy of Nanoconfined Water Molecules

Dipole ordering of water molecules in cordierite: Monte Carlo simulations

“…4 is in good agreement with the peak of the dielectric susceptibility obtained by fitting the relaxation excitation [4] and with the kink of the dielectric measurement data in [4][5][6]. The position of the broad maximum of 𝜒 𝑏 (0) at about 30 K in [5,6] is also close to that in Fig. 4.…”

“…X-ray diffraction studies give a larger estimate for the angle of about 37 • [29]. The four-directions hypothesis is also supported by the presence of the dielectric response of water molecules along both axes in the ab-plane [19][20][21]. The temperatures of about 3-5 K and 15-30 K of the anomalies in the dielectric susceptibilities along the a-and b-axes and the specific heat observed in the experiments [19][20][21][22] are reproduced in my Monte Carlo simulations with ϕ = ±20 • .…”

“…The absence of a phase transition was explained by quantum fluctuations, which are significant in beryl due to the shallow potential that determines six possible dipole directions of the water molecule in the pore. At the same time, in cordierite, the dielectric susceptibility has a maximum at low temperatures [4][5][6], which, together with anomalies in the specific heat [4,7] and the frequency of the optical phonon [8], can be considered as evidence of the phase transition of the dipoles of water molecules of the order-disorder type.…”

“…where 𝑘 𝑒 = (4𝜋𝜀 0 𝜀 𝑟 ) −1 , 𝜀 0 is the electric constant, 𝜀 𝑟 is the relative permittivity of the cordierite matrix (which is considered isotropic here, as measured in [5], in contrast to [12], where it was assumed to be highly anisotropic). r 𝑛𝑚 = r 𝑛 − r 𝑚 is the vector between two dipoles and r 𝑛 = R 𝑛 + u 𝑛 gives the position of the 𝑛 th dipole, where R 𝑛 = 𝑛 1 â + 𝑛 2 b + 𝑛 3 ĉ is the Bravais lattice vector, 𝑛 1,2,3 are integers, and â = 𝑏 √ 3x, b = 𝑏ŷ, ĉ = 𝑐 ẑ are primitive vectors.…”

“…For convenience, the directions of the dipoles in the ac-panels are drawn so as to correspond to their directions in the ab-panels in the same place, since the dipoles have a zero component along the c-axis. time, in cordierite, the dielectric susceptibility due to water molecules has a frequency-dependent maximum at low temperatures [19][20][21], which is typical of relaxor ferroelectrics. This, together with the anomalies in the specific heat [20][21][22] and the frequency of the optical phonon [23] at the same temperature, can be considered as evidence of the phase transition of water molecule dipoles of the order-disorder type.…”