Investigation on Strain Characteristics of Ferroelectric Ceramics for Micromechatronic Actuator Application
Ferroelectric are materials which possess a spontaneous electric polarization and dipole can be reversed by applying an electric field. Ferroelectric materials have good properties such as high induced-strain at low electric fields and reduced hysteresis. Ferroelectric materials are very useful i...
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| Format: | Theses and Dissertations |
| Language: | English |
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เชียงใหม่ : บัณฑิตวิทยาลัย มหาวิทยาลัยเชียงใหม่
2020
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| Online Access: | http://cmuir.cmu.ac.th/jspui/handle/6653943832/69497 |
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| Institution: | Chiang Mai University |
| Language: | English |
| Summary: | Ferroelectric are materials which possess a spontaneous electric polarization and
dipole can be reversed by applying an electric field. Ferroelectric materials have good
properties such as high induced-strain at low electric fields and reduced hysteresis.
Ferroelectric materials are very useful in many applications such as sensor and actuator.
Actuator is a transducer where the external input energy changes displacement or force.
The strain behavior of ferroelectric materials is related to electric field in two types as
piezoelectric and electrostrictive phenomena. This research focuses on lead-free based
(BaTiO3) and lead based (PLZT) ferroelectric ceramics at various parameters consisting
of grain size, phase, crystal structure and temperature.
Strain characteristic and ferroelectric properties of BaTiO3 ceramic sintered at 1350,
1375 and 1400 °C for 2h on grain size effect were observed. It was found that grain size
increased when the sintering temperature was increased. The ferroelectric properties of
ceramic resulted from the grain size effect. The highest strain was 0.064% and
piezoelectric constant of 250.5 pm/V. It can be concluded that dielectric, ferroelectric
properties and strain behavior were affected by grain size.
Strain characteristic and ferroelectric properties of BaTiO3 ceramic sintered at
1375 °C for 1, 2, 4, 6 and 8h on phase combination and microstructure were observed. It
was found that the shape of polarization hysteresis loop changed to slim loop after increasing soaking time resulting from behavior of combination between cubic and
tetragonal phase. The ferroelectric properties of ceramic depend on cubic phase in
combination phase. The strain characteristic in this work could not be analyzed because
the signal from measurement was very bad due to the pores in ceramic.
Strain characteristic and ferroelectric properties of commercial BaTiO3 ceramic
with temperature dependence were observed. It was found that ferroelectric properties
decreased with temperature increase due to the dominant effect from 90o domain rotation
than 180o domain. The maximum strain at 120 oC as 0.148% was caused by mix direction
of 90o and 180o domain reorientation. The butterfly-like shape change to quadratic shape
and reduced area of hysteresis to linear relation of polarization resulted from phase
transition from ferroelectric to paraelectric.
Strain characteristic and ferroelectric properties of barium zirconium titanate
ceramic Ba(Zr0.05Ti0.95)O3 with temperature dependence were observed. It was found that
the right shift of transition temperature from orthorhombic phase to tetragonal (between
40 oC and 60 oC) and high depolarization occurred. Slimmer loop and saturated
polarization were due to the mix rotation between 90o domain and 180o domain but
temperature increase resulted in the decrease of ferroelectric because 90o domains were
easier to rotate. The strain characteristic is quadratic relation. At 60 oC, the maximum
strain was 0.180%, the maximum of piezoelectric constant was 179.8 pm/V and the
highest asymmetry was 0.006% caused by phase transition from orthorhombic to
tetragonal.
Strain characteristic and ferroelectric properties of PLZT, 9/Zrx/Ti100-x ceramics
where x= 70, 65, 60, 55 and 50 mol% were prepared by two-stage sintering. It was found
that at room temperature, the results of strain behavior and ferroelectric properties
depended on Zr/Ti ratio. The temperature dependence of PLZT 9/Zrx/Ti100-x ceramic at
30-140 oC showed that the decrease of strain and area polarization loop (slimmer loop to
linear relation) with increasing temperature was due to the transition from tetragonal to
rhombohedral to paraelectric phase. |
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