摘要:

Although there are many studies for the characterization of piezoelectric thin film, it is still strongly needed to develop the easy and practical way to measure the piezoelectricity existing in thin film. Piezoelectric properties of lead zirconate titanate (PZT) thin film were investigated by a new pneumatic loading method, which has been devised as a more reliable and convenient characterization technique. We have observed the aging phenomena and have examined the effects of poling voltage and time on piezoelectric properties of the PZT thin films. There was no built-in piezoelectricity in virgin films.

ISSN:1058-4587    

DOI:10.1080/10584589908215583

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

0.25Pb(Ni1/3Nb2/3)O3–0. 75Pb(Zr0.52Ti0.48)O3(PNN-PZT) piezoceramics, doped and undoped with BiFeO3and Ba(Cu0.5W0.5)O3oxides, were prepared by conventional mixed-oxide technique, using sintering temperature at 850°C-950°C. Microstructural and compositional analyses of these low-temperature sintered PNN-PZT-Based ceramics have been carried out using XRD and SEM. The effects of dopants on the sintering temperature and dielectric properties of the PNN-PZT ceramics have been investigated. In this paper, we successfully showed that these additives were helpful in both the lowering of the sintering temperature and the improvement of the dielectric properties. The optimum sintering condition is also found.

ISSN:1058-4587    

DOI:10.1080/10584589908215584

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The epitaxial AIN thin films on AI2O3(0001) were prepared byDCfaced-target sputtering. Synchrotron x-ray diffraction was employed to measure the lattice constants a and c of AIN films over a thickness range of 20 Ä to 1 μ m, and the lattice constant as a function of thickness was fitted by the equlibrium theory. From the fitting result, the critical thickness of AIN on AI2O3(0001) to be estimated as 14.4 × 1.5 Ä. The surface oxidation of AIN film was confirmed by electron spectroscopy for chemical analysis(ESCA) profile. We confirmed that the surface oxidation layer thickness was unchanged and the thickness of oxidation layer was estimated about 20–40 Ä.

ISSN:1058-4587    

DOI:10.1080/10584589908215585

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ferroelectric and piezoelectric properties of 2000 Ä thick chemical solution deposited Pb(ZrxTi1−x)O3(PZT) thin films were investigated. Several Zr/Ti ratios were studied: 30/70, 50/50 and 65/35, which correspond to tetragonal, near-morphotropic, and rhombohedral symmetries. In all samples, a {111}-texture is predominant. Longitudinal piezoelectric coefficients and their dc field dependence were measured using the contact AFM method. The expected trend of a maximum piezoelectric coefficient at or near to the MPB was not observed. The composition dependence was small, with the maximum d33occurring in the tetragonal material. To explain the results, crystallographic texture and film thickness effects are suggested.

ISSN:1058-4587    

DOI:10.1080/10584589908215586

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A new process for realizing piezoelectric microdevices has been developed. Suspended piezoelectric clamped-clamped beam resonators have been fabricated using sol-gel deposited lead zirconate titanate (PZT) films as the piezoelectric material, platinum (Pt) as the top and bottom electrode, and silicon dioxide for the supporting beam structure. A five-mask process was used to fabricate the suspended resonators. The process flow included sol-gel PZT deposition, Pt sputter deposition, Pt and PZT argon ion milling, PZT wet and reactive ion etching (RIE), silicon deep reactive ion etching (DRIE), and oxide RIE. Both single-and triplebeam resonators were fabricated with beam widths of 15, 20, and 30 um and lengths of 200 and 400 um. Testing of the resonators produced resonant frequencies between 100 kHz and 1.2 MHz, depending on beam geometry.

ISSN:1058-4587    

DOI:10.1080/10584589908215587

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The diffuse-phase-transition class of ferroelectric materials allows the fabrication of films graded in composition: the consequence of which is an attendant gradient in electric dipole moment density. Alternating electric-field excitation of these graded structures reveal an asymmetrical hysteresis characteristic, together with a static displacement of the hysteresis trace. This displacement bias is observed to be a function of excitation level and temperature, which leads to a giant effective pyroelectric coefficient. Said displacement, for example, provides a continuous open-circuit voltage, or short-circuit current, provided that the structure is held in an isothermal condition. All other combinations of heat, electrical and strain energies suggest a whole new class of devices, and invite ingenious concepts and/or contributions.

ISSN:1058-4587    

DOI:10.1080/10584589908215588

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The high dielectric constant of perovskite-type alkaline earth titanates makes them attractive for use in integrated thin film capacitors for microwave circuits. The application temperatures of those devices such as resonators, filters and phase shifters range from cryogenic temperatures for superconducting devices up to 250°C for semiconducting ICs. Significant material modifications have to be introduced to bring the pure components such as BaTiO3and SrTiO3into formulations which have a suitable temperature coefficient of the dielectric constant. For conventional powder based industrial processes, usually solid solution adaptations and heterogeneous mixtures are employed.

ISSN:1058-4587    

DOI:10.1080/10584589908215589

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

By tailoring Zr/Ti ratio in Pb(Zr,Ti)O3from 45/55 to 75/25, functionally graded PZT thin films were prepared by metal organic decomposition (MOD) technique. P-E hysteresis loops were measured, and polarization was found to shift up or down depending on the direction of the composition gradients of the PZT. This polarization offset was modeled using Poisson's equation in one dimension. Switching charge was also found to be compositional gradient direction dependent.

ISSN:1058-4587    

DOI:10.1080/10584589908215590

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Functionally graded PZT thin films were deposited via MOD technique by varying Zr/Ti ratio in Pb(Zr,Ti)O3. Large signal C-V and small signal C-V were measured by using Symetrix Tester. They are found to be asymmetric compared to that of non-graded PZT capacitors and were gradient direction dependent. It's proposed that the built in potential due to graded polarization is the cause of the asymmetry.

ISSN:1058-4587    

DOI:10.1080/10584589908215591

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The application of thin ferroelectric films for frequency and phase agile components is the topic of interest of many research groups worldwide. Consequently, proof-of-concepts (POC) of different tunable microwave components using either (HTS, metal)/ferroelectric thin film/dielectric heterostructures or (thick, thin) film “flip-chip” technology have been reported. Either as ferroelectric thin film characterization tools or from the point of view of circuit implementation approach, both configurations have their respective advantages and limitations. However, we believe that because of the progress made so far using the heterostructure (i.e., multilayer) approach, and due to its intrinsic features such as planar configuration and monolithic integration, a study on the correlation of circuit geometry aspects and ferroelectric material properties could accelerate the insertion of this technology into working systems. In this paper, we will discuss our study performed on circuits based on microstrip lines at frequencies above 10 GHz, where the multilayer configuration offers greater ease of insertion due to circuit's size reduction. Modeled results of relevant circuit parameters such as the characteristic impedance, effective dielectric constant, and attenuation as a function of ferroelectric film's dielectric constant, tanδ, and thickness, will be presented for SrTiO3and BaxSr1−xTiO3ferroelectric films. A comparison between the modeled and experimental data for some of these parameters will be presented.

ISSN:1058-4587    

DOI:10.1080/10584589908215592

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor