Ferroelectric Phase Transitions in Aurivillius Structure Lead-Free CaBi₄Ti₄O₁₅and CaBi_3.6Nd_0.4Ti₄O₁₅Ceramics

Dielectric and Ferroelectric Properties in Highly Substituted Bi2Sr(A)TiNb2O12 (A = Ca2+, Sr2+, Ba2+) Aurivillius Phases

“…The relationship between ionic radii and T c (ferroelectric) or T m (relaxor) is inconsistent with other alkaline earth substituted Aurivillius phases. , The two-layer compositions Bi 2 (A)­Nb 2 O 9 , where A = Ca 2+ , Sr 2+ , and Ba 2+ , illustrate the expected dependence where A = Ca 2+ is the highest ( T c = 941 °C) and A = Ba 2+ has the lowest ( T m = 108 °C). , The relationship between Δ T m and ionic radii is as expected. Interestingly, two-layer and four-layer Ca 2+ substituted Aurivillius phases do not show relaxor properties, which illustrates that the substantial cation disorder on all crystallographic sites in our samples has a dramatic impact of the physical properties. , The impact of this disorder will be discussed in detail below.…”