Search results for "Zirconate"
showing 10 items of 26 documents
Nonresonant hole burning spectroscopy of the relaxor ferroelectric PLZT
2002
Abstract The polydispersive dielectric response of a lanthanum-modified lead zirconate titanate relaxor ferroelectric was studied using nonresonant hole burning (NHB) spectroscopy. The dynamic heterogeneity of this material was evidenced by the fact that it was possible to burn frequency-dependent spectral holes. The maximum position of the spectral holes depended on the square root of the pump frequency Ω . The refilling of the spectral holes was monitored subsequent to excitation using various pump frequencies. The refilling data could be collapsed onto a master curve by re-scaling them, again, using Ω −0.5 as scaling factor. The refilling time was found to be much longer than the time sc…
Broad Distribution of Relaxation Times in 0.6PMN-0.4PZN Relaxor Ceramics
2007
In this paper dielectric spectra of 0.6PMN-0.4PZN ceramic obtained from broadband dielectric spectroscopy is presented. Measurements revealed an unusual relaxor like nature. Two different processes in the dielectric spectra have been observed. High frequency, or short relaxation times, behaviour is typical for ferroelectric crystals. Longest relaxation times do not follow Vogel—Fulcher dependence, which is unusual for relaxors.
EPR studies of Mn, Fe, Co, and Cu doped PLZT and PMN compositions
1993
Results of Mn, Fe, Co, and Cu admixture EPR spectra studies in PLZT and PMN ceramics are discussed. The spectra of Mn, Fe, and Co ions with dominating absorption at geff = 2.0 and 4.3 are proposed due to d5 (S = 5/2) configurations (Mn2+, Fe3+, Co4+). The latter can be used as probes disclosing specific features (glass-like behaviour) of the structures. The Jahn-Teller ions (Mn3+, Fe4+, Co5+, Cu2+) are responsible for the dopant effect, e.g., the shift of the e(T) maximum to higher temperatures. The microscopic nature of differences of the dopant effect in PLZT and PMN materials and in the Mn Fe Co sequence is analyzed. [Russian Text Ignored].
Dopants and defects: local structure and dynamics in barium cerates and zirconates
2010
In this paper we present an overview of state-of-the-art EXAFS measurements and data analysis on Ba, Ce, Zr, Y, In and Gd local environments in Y:BaCeO3, In:BaCeO3, Gd:BaCeO3, Y:BaZrO3, and In:BaZrO3, at different temperatures, hydration degrees and doping levels. This approach allows to reach unprecedented insights on the peculiar role of the dopant, and its interactions with the other lattice defects. In particular, we evidence that each different dopant shows unique behavior, depending mainly on its electronic structure, and that the usual criterion of ionic radius matching is not useful to outline an effective doping strategy of proton-conducting perovskites. As what concerns the struct…
The strain response of piezoelectric multilayer actuators under combined action of electric field and in-plane uniform load
1997
Abstract The driving field governed strain of lead zirconate titanate piezoelectric multilayer actuators have been made within the 107 N/m2 stress and the 3 · 106 V/m triangle-like upward-down-ward driving voltage. A slow strain component as well as a specific relaxation pattern are detected being additional to the periodic part and attributed to the trapped space charge effects favored by nonuniform electric field of the multilayer.
Interface Effects in Ferroelectric Thin Films
1998
Dielectric, ferroelectric and piezoelectric characteristics in sol-gel derived and pulsed laser deposited (PLD) lead zirconate titanate (PZT), La modified lead titanate (PLT) and zirconate titanate (PLZT) ferroelectric thin films are investigated focusing on maintenance of thin film ferroelectric (FE) properties in a variety of thin film-electrodesubstrate interfaces. Interferometric studies of piezoelectric response of the heterostructures were performed with respect to a DC electrical bias and AC measurement frequency. The asymmetry of piezoelectric coefficient (d33) hysteresis, diminished values of d33, frequency-displacement and spot size — deformation behaviour in the ferroelectric het…
Perovskite thin films grown by direct liquid injection MOCVD
2007
Abstract The continuous scaling down of devices dimensions, in silicon technology, imposes to replace silicon dioxide. Among the potential candidates for new capacitors, some perovskite structure materials (such as titanate or zirconate) show interesting characteristics. The first way to develop perovskite films is to use a mixture of two β-diketonates by varying the solution's cationic ratio. However, our previous results on SrZrO3 showed that a wide parametric study had to be carried on. Another way is to design novel heterometallic precursors that contain both cations on the same molecule. The ligands could be chosen so that peculiar evaporation and decomposition temperatures could be ob…
Giant lateral electrostriction in ferroelectric liquid-crystalline elastomers
2001
Mechanisms for converting electrical energy into mechanical energy are essential for the design of nanoscale transducers, sensors, actuators, motors, pumps, artificial muscles, and medical microrobots. Nanometre-scale actuation has to date been mainly achieved by using the (linear) piezoelectric effect in certain classes of crystals (for example, quartz), and 'smart' ceramics such as lead zirconate titanate. But the strains achievable in these materials are small--less than 0.1 per cent--so several alternative materials and approaches have been considered. These include grafted polyglutamates (which have a performance comparable to quartz), silicone elastomers (passive material--the constri…
Radio and Microwave Spectroscopy of 0.2PMN-0.4PSN-0.4PZN Relaxor Ceramics
2005
Dielectric spectroscopy results of 0.2PbMg 1/3 Nb 2/3 O 3 -0.4PbSc 1/2 Nb 1/2 O 3 -0.4PbZn 1/3 Nb 2/3 O 3 ceramics are reported for 200 < T < 450 K and 20 Hz < v < 11 GHz. Dielectric constant is very high (more than 12000) in the vicinity of the peak. Anomalous broad dielectric relaxation has been observed near and below the temperature of the maximum permittivity, T m (at 1 kHz). The distribution of relaxation times have been calculated directly from the dielectric spectra. At higher temperatures than the maximum permittivity, T m the distribution of the relaxation times is symmetrically shaped (Cole-Cole function satisfactory describes the dielectric response). At lower temperatures, the …
Electroluminescence of (Pb0.91La0.09)(Zr0.65Ti0.35)O3 relaxor ceramics
2013
Abstract Lanthanum doped lead zirconate titanate (PLZT) relaxor ceramics with (Pb 0.91 La 0.09 )(Zr 0.65 Ti 0.35 )O 3 composition exhibit a repolarization induced by electroluminescence (EL) with a pronounced discrete character of emission. It is established that this behavior is related to the reorientation of nanodimensional polar regions in a strong pulsed electric field in the vicinity of a smeared phase transition. The time and temperature dependences of the EL intensity are studied.