Spontaneous long and short-range ferroelectric ordering in Pb0.55La0.30TiO3 ceramics

Abstract

Bismuth-induced ferroelectric relaxor behavior in paraelectric LaAlO3 J. Appl. Phys. 110, 094107 (2011) Weak-relaxor behaviour in Bi/Yb-doped KNbO3 ceramics Appl. Phys. Lett. 99, 192901 (2011) The effects of polarization dynamics and domain switching energies on field induced phase transformations of perovskite ferroelectrics Appl. Phys. Lett. 99, 162903 (2011) Electrocaloric effect in relaxor ferroelectrics J. Appl. Phys. 110, 074113 (2011) On the phase identity and its thermal evolution of lead free (Bi1/2Na1/2)TiO3-6mol% BaTiO3 J. Appl. Phys. 110, 074106 (2011) Additional information on J. Appl. Phys. In this work, we investigated the temperature dependence of short and long-range ferroelectric ordering in Pb 0.55 La 0.30 TiO 3 relaxor composition. High-resolution x-ray powder diffraction measurements revealed a clear spontaneous macroscopic cubic-to-tetragonal phase transition in the PLT relaxor sample at ϳ60 K below the maximum of the dielectric constant peak ͑T m ͒. Indeed, the x-ray diffraction ͑XRD͒ data showed that at 300 K ͑above T m but below the Burns temperature, T B ͒ the long-range order structure corresponds to a macroscopic cubic symmetry, space group number 221 ͑Pm-3m͒, whereas the data collected at 20 K revealed a macroscopic tetragonal symmetry, space group number 99 ͑P4mm͒ with c / a = 1.0078, that is comparable to that of a normal ferroelectric. These results show that for samples with tetragonal composition, the long-range ferroelectric order may be recovered spontaneously at cryogenics temperatures, in contrast to ferroelectric samples with rhombohedral symmetry. On the other hand, x-ray absorption spectroscopy investigations intriguingly revealed the existence of local tetragonal disorder around Ti atoms for temperatures far below T m and above T B , for which the sample presents macroscopic tetragonal and cubic symmetries, respectively.

First-principle studies of the electronic structure and reflectivity of LaTiO3 and Sr doped LaTiO3 (La1-xSrxTiO3)

“…Up to now, studies of the LaTiO 3 based systems [9][10][11] are mainly focusing on the aspects of crystal structure, phase, electrical [12], magnetic, and ferroelectric properties. Less work has been done on the optical properties.…”

Local structure and hybridization states in Ba0.9Ca0.1Ti1−Zr O3 ceramic compounds: Correlation with a normal or relaxor ferroelectric character

“…In lead-based ferroelectric ceramic systems, the ferroelectric character is directly correlated with the electronic properties of both A-site (Pb 2+ ) and B-site (Ti 4+ ) ions [17,18]. Many studies have shown that the density of states (DOS) of oxygen and titanium atoms could provide a more direct correlation with the ferroelectric stability of perovskite-based compounds [19][20][21][22][23][24][25][26][27][28]. They have also reported a significant modification in the hybridization among O 2p, Pb 6sp and Ti 3d states when the ferroelectric character changes.…”

“…In the PLZT and Pb 1Àx Ba x Zr 1Ày Ti y O 3 complex ferroelectric compounds, a reduction in the degree of hybridization between O 2p and Pb 6sp (Ti 3d) states as the amount of La (Ba) increased was directly related to the manifestation of the relaxor character [23][24][25][26][27][28].…”

Síntese, caracterização elétrica e estrutural de cerâmicas ferroelétricas de composição Ba0,90R0,10Ti1-xZrxO3 (R=Ca, Sr)

“…A análise do espectro XANES de uma mesma amostra em função da temperatura mostrou que a estrutura local e a media distância não são afetadas pelos processos de transição de fase observados através das medidas elétricas e de DRX. Estes resultados estão em bom acordo com os observados nas amostras BCZT e como observados em diferentes sistemas cerâmicos apresentando propriedades ferroelétricas(130). Resultados e Discussões Para fins de comparação, amostras de mesma composição foram também sinterizadas a partir do método tradicional em um forno elétrico na temperatura de 1300 o C por 3 horas em ar.Observa-se da Tabela 14 que as amostras sinterizadas pela técnica de SPS apresentam um valor de densidade superior aos das amostras sinterizadas em forno elétrico.…”