Author
M. Wolters
Bio: M. Wolters is an academic researcher. The author has contributed to research in topics: Dielectric & Permittivity. The author has an hindex of 1, co-authored 1 publications receiving 27 citations.
Topics: Dielectric, Permittivity, Curie temperature
Papers
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TL;DR: In this article, the dielectric properties of (Pb,La)Zr0.55Ti0.45O3 ceramics have been investigated as functions of temperature and frequency.
27 citations
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TL;DR: In this article, it was shown that at the so-called diffuse phase transition in relaxor ferroelectrics, the dielectric permittivity e obeys the relation e A / e = 1+0.5(T − T A ) 2 / δ A 2 in a wide temperature range above the temperature of permittivities maximum T m (T m > T A ).
168 citations
TL;DR: In this paper, the authors have shown that ferroelectric diffuse phase transition (DPT) exists near room temperature in lead-free barium zirconate-titanate/barium calcium titanate (BZT?BCT) ceramics.
Abstract: Lead-free barium zirconate-titanate/barium calcium-titanate, [(BaZr0.2Ti0.80)O3]1?x?[(Ba0.70Ca0.30)TiO3]x (x = 0.10, 0.15, 0.20) (BZT?BCT) ceramics with high dielectric constant, low dielectric loss and moderate electric breakdown field were prepared by the sol?gel synthesis technique. X-ray diffraction patterns revealed tetragonal crystal structure and this was further confirmed by Raman spectra. Well-behaved ferroelectric hysteresis loops and moderate polarizations (spontaneous polarization, Ps ~ 3?6??C?cm?2) were obtained in these BZT?BCT ceramics. Frequency-dependent dielectric spectra confirmed that ferroelectric diffuse phase transition (DPT) exists near room temperature. Scanning electron microscope images revealed monolithic grain growth in samples sintered at 1280??C. 1000/? versus (T) plots revealed ferroelectric DPT behaviour with estimated ? values of ~1.52, 1.51 and 1.88, respectively, for the studied BZT?BCT compositions. All three compositions showed packing-limited breakdown fields of ~47?73?kV?cm?1 with an energy density of 0.05?0.6?J?cm?3 for thick ceramics (>1?mm). Therefore these compositions might be useful in Y5V-type capacitor applications.
152 citations
TL;DR: In this paper, a lead free pseudobinary ferroelectric BZT-BCT solid solution system was developed using a solid-state reaction technique and the evolution of the Raman spectra with temperature was used to study the variation of the basic phase transition of BaTiO 3 in these compositions.
81 citations
TL;DR: In this paper, a powder diffraction pattern for Ba0.9Ca0.1TiO3 has been theoretically computed assuming partial substitution of Ba2+ by Ca2+ and the theoretically predicted intensities are in good agreement with those experimentally observed for powders prepared by the precursor route.
Abstract: Ba0.9Ca0.1TiO3 ceramics have been fabricated using powders obtained by calcining mixtures of (i) BaCO3, CaCO3 and TiO2 and (ii) Ba0.9Ca0.1CO3 and TiO2. The precursor Ba0.9Ca0.1CO3 was prepared by a wet technique to ensure homogeneous mixing of Ba and Ca ions at the atomic level. DTA analysis of solid state thermochemical reactions in the two types of mixtures shows that the temperature of reaction completion is 140 degrees C lower for the mixture containing the precursor carbonate solid solution. XRD results indicate better chemical homogeneity for powders obtained by the new route. A powder diffraction pattern for Ba0.9Ca0.1TiO3 has been theoretically computed assuming partial substitution of Ba2+ by Ca2+. The theoretically predicted intensities are in good agreement with those experimentally observed for powders prepared by the precursor route only. Better chemical homogeneity with respect to the distribution of Ca2+ ions leads to more pronounced diffuse phase transition in Ba0.9Ca0.1TiO3 ceramics.
39 citations
TL;DR: In La(III) substituted PbTiO3 ceramics, the reciprocal dielectric constant in the paraelectric phase can be described by the relation with the exponent 1 γ < 2 depending on the composition.
36 citations