The ferroelectric phase transition for bulk and nanosized sodium nitrite was studied by the thermal noise method. It was shown that the intrinsic noise generated in the samples at frequencies above 10 MHz near the ferroelectric phase transition follows the behavior of the dielectric constant. The noise level in the loaded MCM-41 films with unidirectional pores was approximately twice as large as that for the pressed samples.
Stukova, E. V., Baryshnikov, S. B., Shatskaya, Y. A., Charnaya, E. V., & Patrushev, Y. V. (2012). The study of the ferroelectric phase transition in nanoscale sodium nitrite by the method of thermal noise. In Physics Procedia (Vol. 23, pp. 77–80). Elsevier B.V. https://doi.org/10.1016/j.phpro.2012.01.020