摘要:

We are developing actuators and sensors using PZT thin film deposited with hydrothermal method. The merit of the hydrothermal method is thick film and applicable to complicated surface shape. A micro ultrasonic motor has been fabricated. The diameter and length of the stator transducer of the motor were 1.4 mm and 5 mm. The maximum output torque and no-load revolution speed were 0.67 μNm and 680 rpm. A touch probe sensor for measuring surface roughness has been fabricated. The sensor thickness and length were 0.12 mm and 9.8 mm. The resonance frequency and Q factor were 304 kHz and 705. The resolution of the sensor was estimated to 2.4 nm.

ISSN:1058-4587    

DOI:10.1080/10584589908215573

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Effective transverse piezoelectric coefficient e31,fhas been measured on (100)/(001) sol-gel Pb(ZrxTi1−x) thin films with compositions between 30% and 45% Zr. A maximum value of 8.07 ± 0.36 C/m2at 40% Zr is found. The influence of the poling field ranging from 50kV/cm to 250 kV/cm has been evaluated.

ISSN:1058-4587    

DOI:10.1080/10584589908215574

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Lead zirconate titanate (PZT) thick thin films with Zr/Ti ratio of 52/48 have been prepared on ZrO2passivated, 4 inch-diameter silicon substrates with a thermally grown SiO2layer. Both the ZrO2passivated layer and PZT film are deposited through a similar sol-gel processing which can be used to make PZT films with thickness up to 5 μm. Using interdigitated electrode arrays on the upper surface the dielectric and ferroelectric properties of PZT films are characterized, with emphasis on 1 μm-thick films. Dielectric constant of over 1000 with dielectric loss of about 0.01 is achieved for the films. Excellent symmetric hysteresis loops are also obtained with the apparent remanent polarization of around 20 μC/cm2and coercive field of 20 to 30 kV/cm. The results demonstrate that the properties of these PZT films on ZrO2passivated silicon substrates are comparable to that of the PZT films on Pt-buffered silicon substrates, and they can be used to fabricate micromachined, d33-mode unimorph bending transducers which are expected to have much better performance than the conventional, d31-mode bending transducers.

ISSN:1058-4587    

DOI:10.1080/10584589908215575

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

(Ba, Sr)TiO3(BST) thin films were prepared by pulsed laser deposition on the perovskite conductive oxide LaNiO3(LNO), YBa2Cu3O7−δ(YBCO) films, and Pt as a bottom electrode. The crystalline structures and surface microstructrue of the BST deposited on several substrates were characterized by x-ray diffraction measurement and scanning electron microscopy, respectively. The electrode effects on low-frequency dielectric behavior of BST thin films were investigated. The complex dielectric constants of the films were measured as a function of frequency in the frequency range from 0.1 Hz to 10 MHz. BST films grown on metallic oxide substrates exhibited marked dielectric relaxation below 10 MHz. This low frequency dielectric relaxations is attributed to the ionized space charge carriers such as the oxygen vacancies and cation defects in BST film, and the interfacial polarization in the grain boundary region and the electrode/film interface.

ISSN:1058-4587    

DOI:10.1080/10584589908215576

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In order to clarify the decrease of the dielectric constant of Ba0.5Sr0.5TiO3capacitor under the electrical stress, the degradation phenomena including resistant degradation were studied in detail. They were well explained by the increases of the dielectric relaxation and dielectric dispersion which are caused by the generation of oxygen vacancies. This explanation was proved by several additional experiments such as the investigation of Schottky barrier with the stress, the observation of some bubbles and O2plasma annealing. It was also confirmed that the electrical degradation of BST capacitor is effectively suppressed by using iridium (Ir) electrode, especially as a top electrode.

ISSN:1058-4587    

DOI:10.1080/10584589908215577

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

For the first time, we have demonstrated that epitaxial Ba0.6Sr0.4TiO3thin films can be grown on the epitaxial RuO2electrodes by pulsed laser ablation. The Ba0.6Sr0.4TiO3films, deposited on epitaxial (200) oriented RuO2grown on (100) yttria-stabilized zirconia, exhibit single out-of-plane orientation as well as in-plane alignments. The detailed epitaxial relationships between the Ba0.6Sr0.4TiO3films and the RuO2electrodes have been analyzed by X-ray diffraction and transmission electron microscopy.

ISSN:1058-4587    

DOI:10.1080/10584589908215578

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

High dielectric constant (Ba0.65Sr0.35)(Ti1−xZrx)O3(BSTZ) thin films with different Zr content were prepared on Pt/Ti/SiO2/Si substrates at 500°C by rf magnetron sputtering technique. The grain size, dielectric constant, and leakage current density of the 90 nm thick BSTZ films decreased with increasing Zr content. The dielectric constant and dissipation factor of BSTZ films with Zr content of 0.26 were 390 and 0.025 at an applied frequency of 100 kHz, respectively. The leakage current density of films was about 9.0 × 10−9A/cm2at 200 kV/cm. The decrease of leakage current density with increasing Zr content was due to increase of Schottky barrier height. The BSTZ films deposited by rf magnetron sputtering were attractive for semiconductor memory capacitor application.

ISSN:1058-4587    

DOI:10.1080/10584589908215579

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

BaTiO3thin films with (110) preferred orientation are deposited on Si (111) substrates by radio-frequency magnetron sputtering in the temperature range 500–530°C. The crystallinity and microstructure of the films are characterized by X-ray diffraction and atomic force microscopy, respectively. The effects of process parameters such as working pressure, ratio of the flow rates of oxygen to argon, and substrate temperature on crystallization and orientation of the films are investigated. The optimum deposition process for obtaining (100)-oriented BaTiO3films is determined to be at 500°C in argon atmosphere with 5% of oxygen at a total pressure of 0.8mTorr. The (110)-oriented BaTiO3films have a dielectric constant -300 at room temperature and possess high resistivity. The differential conductivity is 5x10−3siemens/cm at zero bias and below 7.0x10−11siemens/cm at ±400kV/cm.

ISSN:1058-4587    

DOI:10.1080/10584589908215580

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ferroelectric Ba1−xSrxTiO3thin films were deposited by pulsed laser ablation on SiO2/Si, RuO2/Ta/SiO2/Si and Pt/Ti/SiO2/Si substrates. The films were weakly crystalline in the as-deposited condition and subsequent crystallization was induced by annealing the films in the range of 550–650°C. The BST films deposited on Pt/Ti/SiO2/c-Si substrates presented wide cracks that were promoted during the annealing process due to the thermal expansion mismatch between the BST films (αBST= 4 × 10−6°C−1) and the Pt (αPt= 9 × 10−6°C−1). Smooth films showing slightly crackeded areas were obtained on SiO2/c-Si and RuO2/Ta/SiO2/Si substrates. The ruthenium oxide thermal expansion coefficient is αRuO2= 5.2 × 10−6°C−1. A cross-sectional analysis at the ferroelectric/substrate interface showed that for the lower annealing temperature (550°C) a mixed amorphous/nanocrystalline microstructure is formed. For temperatures above 600°C a randomly oriented polycrystalline material is obtained. However, an amorphous layer of 4–6 nm still remains on the substrate even after heat-treatments up to 650°C. The dielectric constant of the BST films varied in the range of 30–325.

ISSN:1058-4587    

DOI:10.1080/10584589908215581

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Piezoelectric arrays suitable for high frequency ultrasound have been fabricated using PZT sol gel composite coatings in the thickness range of 5–100μm on aluminum and platinized alumina substrates. The coatings have been quantitatively characterized using impedance measurements to 100 MHz. The analysis provides a direct measure of the piezoelectric coupling coefficient of kt< 0.34. 16 element linear array structures suitable for ultrasound biomicroscopy at 30–40 MHz with elements having dimensions ∼40μm thick, 20–25μm wide and 15μm spacing have been patterned using excimer based laser micromachining. The dielectric and pulse echo responses have been measured.

ISSN:1058-4587    

DOI:10.1080/10584589908215582

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor