摘要:

The high adhesive, single crystal lead germanate films of 5–105 μm in thick were fabricated on platinum substrates byinsitu sol-gel technique. The stoichiometry of the films was closed to 5:3:11 without any oxygen deficiency. The microstructure of better films consisted of closed packed hexagonal crystals of 200–300 μm in size. Ferroelectric transition was sharp with Curie point 170–180°C, ϵ20=30–40, tgδ20≅0.02, ϵmax≅200, Ps=3.2 μC/cm2, Ec=16 kV/cm, ρ=108–109Ωcm. All these parameters (with the exception of ϵmax) were in a good agreement with bulk single crystals ones.

ISSN:1058-4587    

DOI:10.1080/10584580008222237

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The homogeneous solutions of meta-acrylates of Bi, Pb, Sr, Ca, Cu were synthesized, and by spray-pyrolysis of the solutions and following annealing the high temperature superconducting Bi2Sr2CaCu2Ox+Bi2Sr2Ca2Cu3Oxfilms were prepared on LaAlO3substrates. The connection was observed between annealing temperature, film thickness and type, quantity, and forms of impurity phases, such as strontium and calcium cuprates, calcium oxides, strontium oxides. The properties of these films (Ts≅ 81 K, ΔTs≅ 1 K) were shown to take place in case if their microstructure consisted of scale-like plates forming [001] texture. Also, it was concluded that under optimum conditions the Tscould be raised to > 100 K in Bi–containing films

ISSN:1058-4587    

DOI:10.1080/10584580008222238

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The growth and characterisation of sol-gel lead zirconate titanate (PZT) (30/70) thin films on indium tin oxide (ITO) coated glass have been investigated using X-ray diffraction (XRD), transmitting electron microscopy (TEM) and atomic force microscopy (AFM). Perovskite crystallised at 550°C in a random orientation, and all films showed characteristic rosette formations. A seeding and crystallisation model has been proposed to describe the rosette formation process, which is based on the ease of PbO diffusion through the film. The effect of drying temperature on annealed film properties has been examined and when optimised has been shown to improve electrical properties and film flatness. Incorporation of the PZT films into small prototype liquid crystal displays has been done. Application of pulsed poling voltages to the displays has resulted in bulk alignment of the liquid crystal adjacent to poled regions of the PZT layer which remained after the poling voltages were removed.

ISSN:1058-4587    

DOI:10.1080/10584580008222239

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

High quality Ba0.4Sr0.6TiO3and SrTiO3films were grown by Pulsed Laser Deposition on single crystal LaAlO3and MgO substrates. Temperature dependencies of the dielectric constant and loss tangent of the films were studied using planar interdigitated test capacitors with various electrode geometries. The temperature where the maximum or “peak” capacitance occurs (Tpand referred to as the “peak temperature”) is found to depend on the electrode geometry in these films. As much as 40 K difference in Tpwas observed between the STO test capacitors with 5 μm and 40 μm gaps between electrodes. Interface built-in electric field and metal-ferroelectric thermal mismatch strain are considered as possible explanation of the effect of electrode geometry on peak temperature of the capacitors.

ISSN:1058-4587    

DOI:10.1080/10584580008222240

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Little is reported in the literature on the wet etching of PZT and all wet etch recipes described use high concentrations of hydrofluoric acid (HF). Here, a novel recipe which operates in a new regime of extremely low HF concentration is used to wet etch thin film PZT. The recipe provides excellent etch control, minimizes undercut and does not attack photoresist. Unlike most wet PZT etchants it does not leave a lead-rich residue, and the etchant is selective over SiO2and ZrO2. The recipe and preliminary etching results for 5 micron-thick sol-gel deposited PZT films are described in this paper.

ISSN:1058-4587    

DOI:10.1080/10584580008222241

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We report the measurements of pulse polarizations of (Pb, La)(Zr, Ti)O3ferroelectric capacitors as a function of pulse width. Pulse polarizations were measured from the switching current responses in the pulse width range from 1 μs to 1 s. The relation between pulse polarizations(switched(P*) and non-switched polarization(P⁁)) and hysteresis loop parameters was studied. In the case of all write/read pulse widths are same,P* increased butP⁁ decreased with increasing pulse width. These results are explained by poling effects and confirmed by measuring pulse width dependencies with different patterns of pulse trains.

ISSN:1058-4587    

DOI:10.1080/10584580008222242

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A quantity of silver was evaporated onto platinised-silicon (Pt/Ti/SiO2/Si) and then annealed in air to form a silver-platinum alloy. The lattice spacing of the alloy matched that of the composition of lead zirconate titanate (PZT) used. The surface of the silver-platinum alloy was covered in hillocks. It was found that after PZT was deposited by chemical solution deposition (CSD) these hillocks had disappeared. The presence of mobile Pb and the formation of a transient intermetallic phase (Pt3Pb) was taken as the cause for this planarisation. Nucleation of perovskite PZT occurred earlier on silver-platinum compared to a film deposited onto platinised-silicon. The degree of preferred orientation developed for the film on the alloyed electrode was not as good as that found on platinised-silicon.

ISSN:1058-4587    

DOI:10.1080/10584580008222243

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Empirical modeling of the polarization-electric field (P-E) relationship of ferroelectric capacitors subjected to the application of arbitrary electric fields is investigated. Experimental data generated by other researchers has shown that ferroelectric switched charge remains approximately constant when the capacitor is subjected to electric fields which alternate between two fixed values. The current model is based on a dual curve-fit approach to achieve the desired response. The model predicts both saturated- and minor-loop hysteresis when compared to experimental data.

ISSN:1058-4587    

DOI:10.1080/10584580008222244

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Ion implantation into (111) PZT films was done with 150 keV O+-ions using the following doses: 5 · 1010cm−2and 5 · 1013cm−2. The penetration depth of the O+-ion beam (through a 150 nm top Pt-electrode) was calculated with the TRIM. SP program version TRVMC95. For 104particles, 22% of them were calculated to pass the top Pt electrode, 1% of the 104particles were calculated to reach a penetration depth of 150 nm in PZT. The O+-implantation led to a significant improvement (50%) of loss factortanδ. This effect is ascribed within current theory to a decrease of oxygen vacancies (defects). Oxygen vacancies are supposed to be associated by Ti3+, Ti2+and Ti+centers in the perovskite lattice. Evidence for a possible participation of such reduced (charged) titanium defects was obtained by luminescence spectroscopy. Therefore, PZT samples were treated with H2to increase the concentration of reduced Tin+(n<4) ions in the perovskite lattice by chemical treatment. The luminescence spectrum of such reduced samples showed peaks at 3.2, 2.95 and 2.8 eV (surface Ti3+, Ti2+Ti+centers). Furthermore, peaks at 1.87eV and 2.2 eV were observed. These near-midgap states have been ascribed to transitions from Ti3+and Ti2+from the bulk of PZT (3.8 eV excitation energy, T = 6K). Finally, a sharp luminescence peak at 3.34 eV (6K) is assigned as self-trapped exciton luminescence.

ISSN:1058-4587    

DOI:10.1080/10584580008222245

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor