Diffuse first-order phase transition in NaNbO₃:Gd

Abstract

Dielectric permittivity measurements show that (1−x)NaNbO 3 -(x)Gd 1/3 NbO 3 crystals, at x = 0.09, exhibit a first-order phase transition near 150 • C that is diffuse over a wide temperature interval. The area of the ε (T ) thermal hysteresis loop was found to depend both on annealing and cooling temperatures. Optical studies in polarized light show a decrease of the domain sizes at this phase transition. The results obtained are fitted assuming a spatial distribution of Curie temperatures.

Competing antiferroelectric and ferroelectric interactions inNaNbO3: Neutron diffraction and theoretical studies

“…Material engineering of alkaline niobates like pot assium sodium niobate and lithium sodium niobate with ultralarge piezoresponse comparable to Pb (Zr x Ti 1-x )O 3 (PZT) have evoked considerable interest as the next generation ecofriendly lead free piezoceramics 2,3 required for applications as transducers in cell phones, medical implants, etc. Diffuse scattering and relaxor type behavior in NaNbO 3 based solid solutions have also been recently reported 6,7 . Pure NaNbO 3 has an antiferroelectric (AFE) structure at room temperature and exhibits an unusual complex sequence of temperature and pressure driven structural phase transitions which are not clearly understood.…”

Nontrivial dependence of dielectric stiffness on bias field in relaxors and dipole glasses

“…Due to the random fields and distribution of T c 's, this jump diffuses. 29,30 This can be described by introducing a distribution function f (e,T c ) (see the way how to determine the distribution function from experiment in Ref. 30):…”

Diffuse First Order Phase Transitions

“…Recently, one more example was found in a solid solution of antiferroelectrics, NaNbO 3 :Gd [5][6][7]. In order to show that the phases coexist at the diffuse phase transition, a special experiment has been performed [6]. This experiment resembles well-known results for the field hysteresis of magnetization in locally disordered magnetic systems studied by Preisah [8].…”

“…The main phase transition between the solid and gel states of the lipids is diffuse and the fluctuations are strong [3,4]. Recently, one more example was found in a solid solution of antiferroelectrics, NaNbO 3 :Gd [5][6][7]. In order to show that the phases coexist at the diffuse phase transition, a special experiment has been performed [6].…”

“…The present study provides a description of this diffuseness in the framework of the Monte Carlo (MC) computation and a mean field theory (in our Letter to Editor [6] we did not have a possibility to present details of the theory and the MC computation had not been done at that time). We will apply the theory to KTaO 3 :Li (in Letter to Editor [6] we considered the case of antiferroelectric to antiferroelectric phase transition in NaNbO 3 :Gd).…”