摘要:

Large area piezoelectric actuators have been fabricated using sol gel PZT films of up to 20 μm in thickness. The dielectric, ferroelectric and piezoelectric properties have been measured and they are consistent with literature values. Simple vibrational structures have been fabricated based on both planar and coaxial substrates. At the resonant frequency, millimeter vibrations are observed. A PZT ‘In-Line Fiber Optic Modulator’ has been developed by coating a single mode optical fiber with a sol-gel film. Phase shifts of 2° are observed at 100 kHz for a 3 kV/cm electric field.

ISSN:1058-4587    

DOI:10.1080/10584589508012295

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A micro-pump for medical applications is being developed using organometallic derived PZT thin films and silicon micromachining technology. Critical issues include the deposition of ‘thick’ PZT films (1 to 2 μm thickness), film processing compatibility with available Si/SixNy/Ta/Pt structures and the establishing of piezoelectric poling parameters. A processing technique for the preparation of thick PZT films is presented. Piezoelectric properties are characterized by both direct method using alternating compressional force and by converse method using laser interferometry. In poled films of approximately 1. 0 μm thickness, d33values of about 130 pC/N were measured by both direct and converse methods. Maximum d33constants of ≈ 200 pC/N were measured with 8 V bias voltage. Mechanical resonance was excited in a 1 cm by 1 cm silicon substrate by a 0.8 μm thick PZT film poled at 15 V.

ISSN:1058-4587    

DOI:10.1080/10584589508012296

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A micromotor for low power applications is being developed using silicon micromachining technologies and organometallic PZT films sol-gel deposition. The construction of a hybrid ultrasonic motor suitable for batch fabrication is proposed. A fabrication process for the stator resonator compatible with both bulk micromachining and 0.3 μm PZT films deposition on a SiNx/Ta/Pt substrate has been tested. Comparison of PZT actuated and previously fabricated ZnO actuated diaphragms are performed using laser interferometry. PZT samples show promising results for applications where a low voltage operation is a key benefit. Poled PZT films are obtained after process completion and influence of DC biases on the resonance frequencies are observed.

ISSN:1058-4587    

DOI:10.1080/10584589508012297

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Micron-scale (down to 2 μm lateral dimension) La-Sr-Co-O/Pb-La-Zr-Ti-O/La-Sr-Co-O ferroelectric capacitors for high density (> 1 Mbit) non-volatile memories have been successfully fabricated by a full wafer process including ion milling. Reduced dimensional effects as well as fabrication process damage on the micron-size capacitors have been studied. The remnant polarization value was only weakly dependent on the lateral dimension of ferroelectric capacitors. The reliability characteristics such as fatigue, retention and aging of the micronscale ion milled capacitors were similar to those of the large capacitors, which is adequate for non-volatile memories.

ISSN:1058-4587    

DOI:10.1080/10584589508012298

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A broadband CPW phase shifter combining the low loss of high temperature superconductors and the variable dielectric constant of ferroelectrics is described. A phase shift of 80 degrees at 10 GHz with a 30 V bias has been demonstrated. A quasistastic filling factor model has been compared to more sophisticated techniques with excellent agreement.

ISSN:1058-4587    

DOI:10.1080/10584589508012299

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Thin (0.3–50 μm) films of SrxBa(1−x)TiO3(SBT) with x=0.35 − 0.8 have been deposited by pulsed laser deposition onto single crystals of MgO, LaAlO3and thin films of YBa2Cu3O7−δ. The SBT films were characterized morphologically, structurally and electrically at frequencies ≤ 13 GHz. On MgO, smooth, oriented single phase films were obtained at substrate temperatures ≥ 825°C. Films as thick as 10 μm were exclusively (100) oriented. At thicknesses approaching 50 μm SBT films were phase pure but polycrystalline. The dielectric constant of SBT films, as determined from patterned structures using microstrip geometries, was ∼20% of that observed in bulk SBT (εmax(film)=1100 for x=0.5 at 200 K). The temperature dependence of the dielectric constant was broad in comparison to the sharply peaked behavior of the bulk material. The ferroelectric thin film properties described, while significantly different from bulk material, are very encouraging for use in active devices at microwave frequencies.

ISSN:1058-4587    

DOI:10.1080/10584589508012300

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Recent advances in the development of Barium Strontium Titanate ferroelectric composition has made possible reasonable performance of ferroeletric phase shifters to frequencies up to 10 GHz. These material improvements, coupled with phase shifter circuit design changes have resulted in phase shifts greater than 360 degrees with less than 6 dB insertion loss. In particular additives to the BaxSr1-xTiO3composition have been shown to exhibit a consistent electrical phase shift verses DC potential over parameters of temperature and humidity. These ferroelectric material improvements and circuit design changes, included with the development of multiple ferroelectric phase shifters makes possible the fabrication of a low cost electronic scanning antenna. A single four element phase shifter was used with a one dimensional linear antenna array which was constructed on three layers and used an aperture coupled distribution technique. Individual elements of this multiple four element phase shifter were evaluated with respect to uniformity phase shift and insertion loss. The four element antenna was fed by four ferroelectric phase shifters and the phase shifters are corporately fed by the microwave source. The ferroelectric phase shifters are controlled via a dedicated microcontroller which calibrates out element phase variations and provides a real time scan capability for the antenna assembly.

ISSN:1058-4587    

DOI:10.1080/10584589508012301

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A ceramic ferroelectric phase shifting device has been demonstrated using Ba1−xSrxTiO3(BSTO) ceramics.1As part of an effort to optimize the device performance, various composites of BSTO and other nonelectrically active oxide ceramics have been formulated. In general the composites have reduced dielectric constants, ε′, where ε = ε′-iε″ and reduced loss tangents, tan δ, compared to BSTO. The low dielectric constant and low loss tangent reduce the overall impedance mismatch and insertion loss of the device. In addition, the tunability (change in the dielectric constant with applied voltage) is maintained at a relatively high level (15% with an applied electric field of 1.5 V/μm) for dielectric constants of 200. The combination of electronic properties of these materials offer substantially higher operating frequencies, 10 GHz and above. The microstructures including grain size and phase analysis have been examined using SEM and EDX. X-ray diffraction has been used to identify the presence of any secondary phases formed in the composites. The analysis of the phase formation and compositional variations will be related to the electronic properties of the materials.

ISSN:1058-4587    

DOI:10.1080/10584589508012302

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

PZT thin films were synthesized by sol-gel on a Pt/Ti double layer bottom electrode or on a Pt single layer bottom electrode to investigate the bottom electrode dependence of PZT film structure. On Pt/Ti, <111> oriented perovskite grains with 50–100 nm lateral size were densely packed. On Pt, large perovskite grains (2−3 μm) were surrounded by fine pyrochlore grains (about 5 nm), and no certain orientation was observed. TEM and EDX analyses suggested that a fraction of Ti in the Pt/Ti layer diffused along Pt grain boundaries up to the Pt surface and was oxidized during the PZT annealing process. A model for the crystallization of sol-gel derived PZT was proposed, in which TiOx particles at the Pt surface act as nucleation sites for PZT crystallization. This model well explained the experimental results.

ISSN:1058-4587    

DOI:10.1080/10584589508012303

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of temperature and atmosphere during the crystallization process on electrical and reliability characteristics of ferroelectric capacitors, obtained by sol-gel deposition of lead zirconate titanate films, have been examined for non-volatile memory applications. Films with good ferroelectric properties were achieved after 600 and 650 °C, 1 hour crystallization in a O2atmosphere: a remanent polarization of about 20 μC/cm2and a coercive field of 125 kV/cm was obtained with a durability factor better than 108cycles.

ISSN:1058-4587    

DOI:10.1080/10584589508012304

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor