Study of nanostructural behavior and transport properties of BaTiO3 doped vanadate glasses and glass–ceramics dispersed with ferroelectric nanocrystals

Ferroelectricity in the glassy material of the composition Bi2O3–Pb3O4–CuO–K2O

“…It is seen from Table 3 that W = W − W H (0.575 eV) is higher than the calculated value. Similar results have been reported for other borate and vanadate glasses [29,37,44]. This discrepancy had been explained as the effect of the partial charge of the cations of the glass forming oxides on activation energy for hopping conduction in TMO glasses [29,37,48].…”

“…The condition for formation of small polaron is, however, given by J ≤ W H /3 [37]. The limiting value of J calculated from the right-hand side of expression (17) or (18) at 400 K is of the order of 0.013 eV, and therefore the condition for the existence of small polaron is satisfied.…”

“…4 indicate that the endothermic peak at T C , is due to a first-order phase transition while the sample is remained in its glassy state, where T C < T g < T x , as shown. Typically in the field of glass-ceramic ferroelectrics the endothermic peak due to the Curie's temperature is observed in DTA thermograms only after devitrifying the amorphous samples [37,39]. Fig.…”

“…Next, we estimate the optical phonon frequency ( o ) in Eq. (7) using the experimental data from Table 3, according to k D = h o (h is the Plank's constant) [37]. To determine o for the present composition, the Debye temperature  D of the present glass was obtained to be 700 K at the inflection point of Fig.…”

“…VRH was reported in BaO-CaO-Fe 2 O 3 -P 2 O 5 glasses [31] as well. However, we reported recently the nature of polaron hopping mechanism (adiabatic or non-adiabatic) in a series of glasses and glass-ceramic nanocrystals of V 2 O 5 -BaTiO 3 series [37]. It should be mentioned that the above two models were based, in common, on a single phonon approach.…”