| 1. |
- Abadei, Saeed, 1961, et al.
(författare)
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Low frequency characterisation of laser ablation deposited thin Na0.5K0.5NbO3 (NKN) films for microwave application
- 2001
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Ingår i: Integrated Ferroelectrics. - : Informa UK Limited. - 1058-4587 .- 1607-8489. ; 263:1, s. 173-179
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results on three types of Na0.5K0.5NbO3 (NKN) film capacitor structures are presented. The epitaxial NKN thin films have been deposited on (100) Si (high resistivity), SiO2/Si (low resistivity) and Pt/Si (low resistivity) substrates using laser ablation deposition. Both straight slot and interdigital electrode have been deposited on top of the NKN films. The leakage current and low frequency dielectric properties (I-V, C-V, tanδ-V) of the structures have been measured at 1 MHz as a function of electric field at room temperature. In all three types of capacitor structures the leakage currents in a-b plane are very small, while along c-axis there are extremely large leakage currents. On low resistivity silicon substrates the tunability of the dielectric permittivity is about 12% and loss tangent is low also. On high resistivity (ρ>10 kOhm cm) silicon substrate the tunability at 1 MHz is extremely high, about 10 times, and the losses are also high. On the other hand at microwave frequencies the losses are small (tanδ
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| 2. |
- Brunahl, J., et al.
(författare)
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Non-destructive pulsed technique to characterize functional properties of micromachined bulk PZT
- 2001
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Ingår i: Ferroelectrics (Print). - 0015-0193 .- 1563-5112. ; 263:1-4, s. 1487-1492
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Tidskriftsartikel (refereegranskat)abstract
- In this report, a non-destructive pulsed technique is presented to characterize all relevant properties of machined bulk PZT material. The proposed method is based on recording of the transient current as response on the short voltage pulse applied to the ferroelectric acoustic element. This new promising experimental technique makes it possible to measure mechanical and electrical properties fast, reliably and reproducibly. Among other results we can obtain electromechanical coupling coefficient, dielectric loss factor tan 8, mechanical quality factor Q, dielectric constant, capacitance, resonant frequency and Curie temperature T-c. The temperature dependence of above mentioned parameters can be studied as well very easily.
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| 3. |
- Frantti, J, et al.
(författare)
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Local and average structure of lead titanate based ceramics
- 2002
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Ingår i: Ferroelectrics. - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 266:1, s. 73-90
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Tidskriftsartikel (refereegranskat)abstract
- The revised lattice dynamics of Pb(Zr x Ti 1 -x )O 3 (PZT) with 0.10 ≤ x ≤0.54 ceramics is reported. The phase transition from tetragonal phase to the monoclinic phase is proposed to occur via locally distorted regions. Neutron diffraction data suggests that these local regions transform to the monoclinic phase with decreasing temperature, when x ≈0.50.
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| 4. |
- Hirohashi, Junji
(författare)
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Fabrication of 90-degree domain structures in KNbO3 single crystals
- 2003
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Ingår i: Ferroelectrics (Print). - 0015-0193 .- 1563-5112. ; 282, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- New domain (90 domain) structure in the KNbO 3 single crystal could be fabricated by applying electric field at room temperature. The coercive electric field of 90 domain is very low (140 V/mm) compared with that of 180 domain (250 V/mm). A very sharp boundary was observed across the whole sample thickness (2 mm). Fabricated 90 domain structures were also confirmed by the (101) surface profile measurement using the optical interferrometer and two peaks of the 404 X-ray diffraction analysis. We also demonstrated the fabrication of periodically 90 domain structures with 200 μ m period without generating unwanted domain structures. As 90 domain structure feels the difference of the refractive index, new applications other than 180 domain will be possible.
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| 5. |
- Korkishko, Y. N., et al.
(författare)
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Proton exchanged LiNbO3 optical waveguides : Nonlinear, electrooptical and photorefractive properties
- 2001
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Ingår i: Ferroelectrics (Print). - 0015-0193 .- 1563-5112. ; 264:04-jan, s. 1983-1988
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Tidskriftsartikel (refereegranskat)abstract
- We show that proton exchanged LiNbO3 waveguides exhibit very complex structural chemistry. Seven HxLi1-xNbO3 crystallographic phases have been identified in PE LiNbO3 waveguides. A correlation is done between the electroptical, nonlinear and photorefractive properties, the processing conditions and the refractive index changes of the waveguides.
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| 6. |
- Reihmann, M., et al.
(författare)
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Structure and Properties of New de Vries SmA∗ Liquid Crystals
- 2004
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Ingår i: Ferroelectrics. - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 309, s. 111-119
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Tidskriftsartikel (refereegranskat)abstract
- We synthesized a chiral mesogen AC11 and two different siloxanes MSi2-AC11 and DSi3-AC11 derived from it by a hydrosilylation reaction. The effects of varying the molecular architecture were investigated with special attention being devoted to the occurrence of the de Vries SmA* phase. Strong hints that all the three molecules follow the scenario suggested by de Vries were found in the behavior of the susceptibility by studies of their electrooptical response in the SmA* phase. In particular DSi3-AC11 containing two mesogens interconnected by a siloxane spacer presented a critical exponent gamma as high as 1.97, indicating a practically pure de Vries behavior Temperature-dependent X-ray analysis revealed that the three materials underwent a small layer shrinkage at the SmA*-SmC* transition.
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| 7. |
- Shur, Vladimir, et al.
(författare)
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Self-Organization in LiNbO3 and LiTaO3 : formation of Micro- and Nano-Scale Domain Patterns
- 2004
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Ingår i: Ferroelectrics (Print). - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 304, s. 111-116
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Tidskriftsartikel (refereegranskat)abstract
- We review the study of self-organized formation of several types of quasi-regular micro- and nano-scale domain patterns in single crystalline LiNbO3 and LiTaO3 samples with artificial surface dielectric layers. The domain images revealed by chemical etching have been visualized using optical, scanning electron and scanning probe microscopy (SPM) in contact atomic force mode. SPM piezoresponse imaging mode allows us to investigate the domain structure under the sample surface. We classify the obtained quasi-regular domain structures and discuss the mechanism of their formation and self-maintained growth.
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| 8. |
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| 9. |
- Ozolinsh, M, et al.
(författare)
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Electrooptic PLZT ceramics devices for vision science applications
- 2002
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Ingår i: Ferroelectrics. - 0015-0193. ; 273:1, s. 2509-2509
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Tidskriftsartikel (refereegranskat)abstract
- The present work reports on spectral transmission and scattering dependencies, the status of scattered light polarization for PLZT ceramics elements working in the electrically induced longitudinal light scattering mode. Experiments are done with the double optical integrated sphere technique. Several devices using the electrically controlled scattering effect are developed - eye occluders for studies of dynamics of visual and stereoscopic response, an artificial eye model to simulate optical transfer function of the eye with cataract of the lens.
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| 10. |
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