Wyniki wyszukiwania - BazTech

1

Wpływ technologii wytwarzania na stopień rozmycia ferroelektrycznych przemian fazowych w ceramice typu PZT

Dudek J., Bochenek D.

Materiały Ceramiczne

|

2010

|

T. 62, nr 3

393-399

PL

Materiałem użytym do badań wpływu technologii wytwarzania na stopień rozmycia przemiany fazowej w ceramice ferroelektrycznej były domieszkowane roztwory stałe typu PZT. W pracy wykazano, że o stopniu rozmycia przemian fazowych w PZT decydują głównie dwa czynniki: fluktuacje składu w mikroobjętościach ceramiki oraz niejednorodność rozkładu defektów i naprężeń mechanicznych. Na te dwa czynniki z kolei duży wpływ mają stosowane warunki technologiczne. Przy porównywaniu stopnia rozmycia przemian fazowych różnych materiałów ceramicznych typu PZT istotnym jest zastosowanie tego samego kryterium.

EN

Admixed solid solutions of the PZT type were used as a material to test the influence of ceramic material production technologies on a degree of phase change broadening. It has been shown in the work that two main factors decide about the degree of phase change broadening in PZT, that is composition fluctuations in the ceramic micro-volumes and heterogeneity in the distribution of defects and mechanical stresses. Technological conditions applied have a great influence on the two factors above. While comparing the degree of phase change broadening for different ceramic materials of the PZT type it is important to use the same criterion.

2

Ferroelectric and ferroelectromagnetic ceramics in a view of possibilities to be used in electroacoustic

Czerwiec M., Zachariasz R., Brzezińska D., Ilczuk J.

Hydroacoustics

|

2008

|

Vol. 11

63-70

EN

Ferroelectric ceramics were born in the early 1940's with the discovery of the phenomenon of ferroelectricity as the source of the unusually high dielectric constant in ceramic barium titanate capacitors. Since that time, they have been the heart and soul several multibillion dollar industries, ranging from high-dielectric-constant capacitors to later developments in piezoelectric transducers, positive temperature coefficient devices, and electrooptic light valves. Various ceramic formulations, their form, fabrications, functions, and future are described in relation to their ferroelectric nature and specific areas of applications. This paper is intended to illustrate practical uses of ferroelectric and ferroelectromagnetic ceramics obtained and investigated by the authors.

3

Non-linear electrooptical effects in chiral liquid crystals

Dardas D., Kuczyński W.

Opto-Electronics Review

|

2004

|

Vol. 12, No. 3

277-280

EN

We studied the electrooptical effects in ferroelectric liquid crystals at both the fundamental and the second harmonic frequency. The linear effects caused mainly by the changes in optic axis position give rise to the changes in the intensity of light passing the sample placed between crossed polarizers. The electric field causes also changes in the shape of the indicatrix. Both mentioned effects influence the second harmonic response. We observed that the defects present in ferroelectric liquid crystal sample affect the electrooptical response to a large extent. This influence is especially significant for the second order harmonics. The depth of light modulation depends on kind of alignment (bookshelf or chevron).

4

Macroscopic description of the non-linear electro-mechanical coupling in ferroelectrics

Bohle U., Kamlah M., Munz D., Tsakmakis C.

Applied Mechanics and Engineering

|

2000

|

Vol. 5, no 4

959-970

EN

Our objective is the construction of a phenomenological ferroelectricity model for general electro-mechanical loading histories, which is simple enough to be implemented in an FE-code with reasonable expenditure. In this paper, we motivate and verify the one-dimensional formulation of such a model. This is done by introducing remanent polarization and remanent strain as internal variables besides stress, strain, electric field and polarization. Polarization induced anisotropy is taken into account to the extent deemed necessary. For the sake of simplicity, no rate effects are included. By bilinear approximation the following characteristic phenomena of macroscopic ferroelectricity are represented: dielectric hysteresis, polarization induced piezoelectricity, butterfly hysteresis, ferroelastic hysteresis, mechanical depolarization, field dependent coercitive stress.