Characterization of (0.4)Pb 2 (In,Nb)O 6 :(0.6)Pb(Mg 1/3 Nb 2/3 )O 3 relaxor ceramics

2012

MRS Proc.

Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 ceramics were fabricated by mixed-oxide route. The compositions along morphotropic phase boundary were investigated. Dielectric properties and piezoelectric coefficient were measured. The maximum relative permittivity is 33600 found in the (PIN-PT) x (PMN-PT) 1-x ceramics with x = 0.1 at 167 °C. When increasing the amount of Pb(In 1/2 Nb 1/2 )O 3 , the piezoelectric coefficient of the ceramics decreases but the phase transition temperature increases. The selected-area electron diffraction patterns show the pseudocubic perovskite symmetry. Diffuse scattering is found in the diffraction pattern taken at higher order zone axis. Transmission electron microscopy study shows that the morphology of ferroelectric/ferroelastic domains is neither tetragonal nor rhombohedral configuration.

Section: Dielectric and Piezoelectric Propertysupporting

confidence: 82%

Ferroelectric domain morphology, electrical and electromechanical properties of Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ ceramics

2012

MRS Proc.

“…These domains are assumed to originate from the mixed ordering of the three different B-site cations, Mg, Nb and In, either in stoichiometric or nonstoichiometric combinations. This form of mixed ordering in (0.4)PIN:(0.6)PMN was first observed by Baba-Kishi et al [29,30].…”

Section: Global Mixed Ordered Nanodomains In Pstsupporting

confidence: 61%

Nanoscale global mixed ordering of B-site cations in Pb₂M′M′′O₆complex perovskite relaxors

Baba-Kishi

Meng

2006

Philosophical Magazine

Self Cite

We have observed compositionally heterogeneous, uniformly distributed and closely interconnected nanoscale and sub-nanoscale domains in complex perovskite-structured relaxors. These domains are interpreted as originating from global mixed ordering, formed by numerous non-stoichiometric combinations of B-site cations across the entire bulk of the relaxor crystals and ceramics. The association between global mixed ordering and the origin of the forbidden reflections has been explained theoretically and experimentally. Various models of global mixed order-disorder are proposed, simulated and subsequently compared with dark-field and high-resolution TEM images, showing unambiguous agreement between the models and the observed TEM images and the diffraction patterns. Careful and extensive case studies of Pb 2 (ScTa)O 6 crystals and (0.4)Pb 2 (InNb)O 6 :(0.6)Pb(Mg 1/3 Nb 2/3 )O 3 ceramics show that mixed order-disorder originates from a global B-site chemical heterogeneity. The findings are analyzed using a normal statistical distribution approach, which is supported by the length-scale of the experimentally observed domains.

“…A subgroup of these oxides fall into the category of complex perovskite relaxors, in which there is dispersion in the dielectric constant versus temperature as a function of frequency [1]. The relaxor oxides subjected to significant studies include Pb 2 (Sc,Ta)O 6 , Pb(Mg 1/3 ,Nb 2/3 )O 3 , Pb(Sc 0.5 ,Nb 0.5 )O 3 and Pb(Zr,Ti)O 3 [2][3]. The ceramics, films and crystals of these materials have interesting structural, microstructural, and domain characteristics that can be studied by transmission electron microscopy, TEM.…”

mentioning

confidence: 99%

Radiation Damage by Ar+ Ion-Milling in Ferroelectric Oxides.

Baba-Kishi

2005

MAM

Ferroelectric oxides have a variety of applications as infrared sensors, actuators and non-volatile memory devices. A subgroup of these oxides fall into the category of complex perovskite relaxors, in which there is dispersion in the dielectric constant versus temperature as a function of frequency [1]. The relaxor oxides subjected to significant studies include Pb 2 (Sc,Ta)O 6 , Pb(Mg 1/3 ,Nb 2/3 )O 3 , Pb(Sc 0.5 ,Nb 0.5 )O 3 and Pb(Zr,Ti)O 3 [2][3]. The ceramics, films and crystals of these materials have interesting structural, microstructural, and domain characteristics that can be studied by transmission electron microscopy, TEM. In most cases where TEM study is required, Ar + ion-milling of the samples must be carried out.Pb-based oxides undergo some degree of milling radiation damage [4]. The severity of damage depends on the sample thickness immediately before milling and the time used to obtain electron transparent regions. Radiation damage is often visible as mottled or spotty background contrast, which originates from fully amorphous to partially amorphous transformations. A thin amorphous layer may also be found at the outer edge of most specimens subjected to about 15 minutes of irradiation. At the microstructural level of investigations, the adverse influence of radiation damage on image formation can be minimal. With the exclusion of the specimen outer edge, antiphase boundaries, ferroelectric domains, structurally ordered domains can be imaged in regions where radiation damage is present. However, in high-resolution TEM (HRTEM) studies, evidence of structural distortion or change originating from radiation damage can be easily observed. The result of such damage is poor quality images, lack of sufficient contrast and uncertainty about the true structure or interplanar spacing. In radiation damaged oxides, fine incommensurate structures can be difficult to identify or distinguish from altered clusters. Here, various examples of the appearance of radiation damage in Pb 2 (Sc,Ta)O 6 are illustrated. Images recorded from milled samples and those recorded from crushed samples, Figures 1a-d, illustrate the high level of structural damage in milled samples. We have noted that thick samples, which require longer period of milling, undergo greater level of damage. We have also found that reducing sample thickness to about 20 microns, prior to thinning, as well as careful polishing by various grades of diamond paste, minimize radiation damage and improve image quality by a factor of about two. It is evident that grinding and polishing a sample to such a thickness is generally time-consuming and rather difficult. However, the gains are significant in that the milling time is substantially reduced to about 15 minutes in some cases and the TEM results recorded are certainly more representative of the true structure.