O3 Thick Films Research Articles

Out-of-plane actuation of silicon micro-cantilever based on (Pb, La) (Zr, Ti)O3 antiferroelectric thick films

With micro-machining technologies, the micro-cantilevers of Si-based antiferroelectric (Pb, La) (Zr, Ti)O3 thick films were fabricated, and five sizes of cantilevers were completed in one chip. Out-of-plane motion of the cantilever structure was described with the out-of-plane actuation method. Under the square wave excited by the voltage of 42 ± 2 V, the micro-cantilevers presented the good performance, such as high vibration velocity of 0.93 m/s and big cantilever tip displacement of 31 μm due to the electrical field induced phase transition in the thick film. The drive voltage as the phase-transition voltage was applied to the antiferroelectric material layers for the out-of-plane motions measured by Micro System Analyzer (MSA-400), and hence the 1st-order resonance frequency of the cantilevers was 40.08 kHz. These results reveal that the antiferroelectric thick films (Pb, La) (Zr, Ti)O3 are of characteristics of large electrostrictive strain and show the potential and board application for the micro-devices with those films in micro-actuators and high-speed digital switches.

Preparation of BaTiO3-based thick films with c-axis-preferred orientation using screen printing

Pb(Zr,Ti)O3 and related materials have been lauded for their piezoelectric properties, but their toxicity has driven the search for alternative materials with the same high performance in electronic devices. Among these, BaTiO3-based materials are regarded as excellent substitutes. Using a screen printing method, in this study, we prepare BaTiO3 thick films on ZrO2 stabilized with 3 mol % Y2O3 (YSZ) or MgO ceramics with Pt bottom electrodes. BaTiO3 thick films prepared on YSZ and MgO substrates preferentially oriented along the a- and c-axes, respectively. The remanent polarization Pr of the MgO-based films was higher than that of the YSZ-based films (10.8 µC/cm2 vs 6.5 µC/cm2) and comparable to that of BaTiO3 bulk ceramics. Thermal expansion measurements of BaTiO3, YSZ, and MgO ceramics suggested that compressive stress was exerted on the BaTiO3 thick films, causing them to orient along the c-axis. (Ba0.92Ca0.08)(Ti0.975Zr0.025)O3 thick films were also prepared on the YSZ and MgO substrates and showed similar preference for the c-axis on MgO. However, the remanent polarization of (Ba0.92Ca0.08)(Ti0.975Zr0.025)O3 thick films prepared on MgO was greater than that of bulk ceramics (14.9 µC/cm2 vs 11.0 µC/cm2).

Preparation and characterization of lead zirconate titanate thick films prepared by chemical solution deposition for MEMS applications

Lead zirconate titanate (PbZrxTi1−xO3, PZT) films are widely used in silicon based microelectromechanical systems (MEMS) due to their high piezoelectric and electromechanical coupling coefficient. Si3N4 is often needed as a masking layer to protect Si during wet etching. In this paper, the preparation and characterization of Pb(Zr0.52Ti0.48)O3 thick films deposited on Pt/Ti/Si3N4/SiO2/Si substrate by chemical solution deposition were studied. PZT films with a thickness of 2μm were spin-coated on the substrates and pyrolyzed at 350°C, and then annealed at 650°C. PZT thick films exhibit highly (100) preferential orientation. The dielectric constant and loss tangent of the films are 2370 and 0.046 at 1kHz, respectively. The remnant polarization (Pr) and the coercive fields (Ec) are 32μC/cm2 and 56kV/cm, respectively. PZT films on patterned Si wafers have been studied for the applications on biosensors and medical ultrasound transducers.

High performance screen printed Pb(Zr0.46Ti0.54)O3−Pb(Zn1/3Nb2/3)O3−Pb(Ni1/3Nb2/3)O3 thick films by one-step co-firing method

High performance screen-printed PNN−PZN−PZT thick films have been successfully prepared using a new one-step co-firing method at relatively low sintering temperature, leaving out preceding binder removal and subsequent electrode-made processes. And the dependence of microstructure, densification and electrical properties on the content of sintering aids has been investigated. The specimens with 1wt% sintering aids sintered at 850°C exhibits markedly enhanced piezoelectric and dielectric properties: d33=202 pC/N, ε33T/ε0=987, tanδ=1.8%, Tc=295°C, and Pr=14.02μC/cm2. Furthermore, there is no obvious Ag diffusion into PZT thick films, indicating the favorable coherence. Such prominent properties of PZN−PNN−PZT thick films using one-step co-firing method can be applied to multilayer thick films and further MEMS device applications.

X-ray diffraction measurement of residual stress in sol-gel grown lead zirconate titanate thick films on nickel-based super alloy substrate

Residual compressive stress of Pb(Zr0.52Ti0.48)O3 thick films was investigated using residual strains derived from X-ray diffraction patterns. Sin2ψ method was applied for the 5, 10 and 15 µm sol-gel derived thick films annealed at 700°C for 1 hr as high frequency structural health monitoring square-shape transducers of 10×10 mm, deposited onto the curved nickel-based super alloy substrates. A triaxial model was proposed based on piezoelectric constitutive equations, and Bragg’s law at a large diffraction angle (∼89o) was utilized considering the electromechanical coupling factor as well as elastic, dielectric and piezoelectric constants. Thickness variations led to a significant change in residual stress magnitudes delineated from more-accurate triaxial model compared to small angle plane-stress results not considering the piezoelectric coupling effects.

Electric, magnetic and high frequency properties of screen printed ferrite-ferroelectric composite thick films on alumina substrate

Purpose – The purpose of this article is to study the effect of ferrite content on electric, magnetic and microwave properties of screen-printed y(Ni0.4Co0.2Cd0.4Fe2O4) + (1 − y)Pb(Zr0.52Ti0.48)O3 (y = 0.0, 0.15, 0.30, 0.45, 1.0) thick films on alumina. Design/methodology/approach – Thick films of ferrite–ferroelectric composite on alumina substrate have been delineated using screen printing technique. The structural analysis was carried out using X-ray diffraction method and scanning electron microscopy. The DC electrical resistivity was measured using the two-probe method. The magnetic measurement was carried out using a vibrating sample magnetometer. Microwave absorption was studied in the 8-18 GHz frequency range by using the vector network analyzer (N5230A). The permittivity in the 8-18 GHz frequency range was measured by using voltage standing wave ratio slotted section method. Findings – The formation of two individual ferrite–ferroelectric phases in composite thick films was confirmed by the X-ray diffraction patterns. The scanning electron microscope morphologies show the growth of cobalt-substituted nickel cadmium ferrite grains which are well dispersed in lead zirconium titanate matrix. The DC electrical resistivity increases with increase in ferrite content and decreases with increase in temperature. The present ferrite shows ferromagnetic nature and it increases saturation magnetization and coercivity of the composite thick films. Tuning properties are observed in the Ku-band and broadband X-band microwave absorption is observed in the composite thick films. The imaginary part of permittivity increases with an increase in ferrite content, which increases microwave absorption. The real part of microwave permittivity varied from 17 to around 22 with an increase in ferrite content and it decreases with frequency. The microwave conductivity, which increases with an increase in ferrite content, reveals the loss of polaron conduction, which supports the dielectric loss in the microwave region. Originality/value – Electric, magnetic and microwave properties of screen-printed y(Ni0.4Co0.2Cd0.4Fe2O4) + (1 − y)Pb(Zr0.52Ti0.48)O3 (y = 0.0, 0.15, 0.30, 0.45, 1.0) composite thick films on alumina substrate is reported for the first time.

Percolation in the dielectric function of Pb(Zr, Ti)O3 – Pb2Ru2O6.5 ferroelectric – metal composites

A set of composite PbZr0.53Ti0.47O3 − xPb2Ru2O6.5 (PZT 53/47 − xPRO) and pure PbZr0.53Ti0.47O3 (PZT 53/47), PbZr0.38Ti0.62O3 (PZT 38/62) and PbZr0.36Ti0.64O3 (PZT 36/64) thick films (thicknesses 20–30 µm, porosity 25–50%) prepared by screen printing on (0001) single-crystal sapphire substrates, were studied using Fourier-transform infrared (FTIR) reflectivity and time-domain terahertz transmission spectroscopy. The compositions studied with 10, 15, 20 and 25 vol% PRO were around the electrical percolation threshold in the bulk ceramic composites (~17 vol%), known from impedance spectroscopy by Bobnar et al (2008 Appl. Phys. Lett. 92 182911). To obtain the effective dielectric functions of the films, we accounted for their porosity by using the Lichtenecker model. Using the dielectric functions of bulk pure PZT 53/47 ceramics and PRO single crystals from the literature available, effective dielectric functions were compared with those obtained using the generalized effective medium model by McLachlan with percolation threshold and critical percolation exponents, which fit the low-frequency data by Bobnar et al. The effective dynamic response in all the samples was dominated by an overdamped THz conductivity peak (central mode), as in pure PZT. The percolation threshold was not particularly apparent in the polar-phonon frequency range as it characterized the localized response. Unlike the low-frequency permittivity, which diverged at the percolation threshold, the effective microwave–terahertz permittivity increased above it.

Giant electrocaloric effect in BaZr0.2Ti0.8O3 thick film

We report the giant electrocaloric effect (ECE) of BaZr0.2Ti0.8O3 (BZT) thick film near room temperature. The BZT thick film was fabricated by the tape casting method with the thickness of 12.0 μm. Due to the near invariant critical point composition, relaxor behavior, and the stress generated between the film and the substrate, the thick film exhibits a large adiabatic temperature drop ΔT = −7 °C under 19.5 MV/m electric field, large EC coefficient ΔT/ΔE = 0.50 × 10−6 K · m · V−1, ΔS/ΔE = 0.88 × 10−6 J · m · kg−1 · K−1 · V−1 over a wide temperature range near room temperature, where ΔS is the isothermal entropy change and ΔE is the applied field. These high EC properties and possibility of fabrication of the EC ceramics into multilayer ceramic capacitor configuration provide solution for the application of the EC material for practical cooling device applications.

Phase transition current of antiferroelectric (Pb0.97La0.02)(Zr0.95Ti0.05)O3 thick films under thermo-electric coupled field

Antiferroelectric (Pb, La)(Zr, Ti)O3 multilayer thick films with thickness of 3817nm were fabricated by sol–gel processing on Pt(111)/Ti/SiO2/Si(100) substrates. The characteristics of the phase transition current induced by temperature and transient pulse electric field were further investigated in detail. It showed that the phase transition current density was about 1.25×10−6A/cm2 in the thermo-electric coupled field, which was 10 times smaller than that in a single temperature or electric field. In addition, the transient phase transition current density induced by pulse-voltage was up to 2.48×10−5A/cm2, which could be used as the trigger signals in sensor and micro-switch in the complicated circumstance. At the same time, the results showed that the films had good reproducibility and stability by many repeated experiments. These results were very important for the antiferroelectric materials applied on micro electromechanical systems (MEMS) devices.

High energy-density 0.72Pb(Zr0.47Ti0.53)O3-0.28Pb[(Zn0.45Ni0.55)1/3Nb2/3]O3 thick films fabricated by tape casting for energy-harvesting-device applications

0.72Pb(Zr0.47Ti0.53)O3-0.28Pb[(Zn0.45Ni0.55)1/3Nb2/3]O3 (0.72PZT-0.28PZNN) thick films were prepared by using a tape casting method to develop new materials with high energy-density applicable to energy-harvesting devices. The piezoelectric strain constant (d 33), dielectric constant (ɛ 33 /ɛ 0), piezoelectric voltage constant (g 33) and transduction coefficient (d 33·g 33) of the films were affected by the sintering temperature. These results could be attributed to the crystal structure, microstructures and secondary phases. However, the dielectric loss (tanδ) of the films was not changed remarkably with increasing sintering temperature. Typically, a d 33 of 452 pC/N, ɛ 33 /ɛ 0 of 1444, d 33·g 33 of 20,340 × 10−15 m2/N and tanδ of 0.15% were obtained for the films sintered at 1050 °C for 1 h. The power generation performance of the piezoelectric unimorph cantilever was assessed to demonstrate the feasibility of the 0.72PZT-0.28PZNN piezoelectric thick film. Also, theoretical models were employed to predict the resonance frequency of the unimorph cantilever generator, and the predicted values were compared with experimental data.

Thick Film Laser Sintering: An Evidence for Two-step Process

The results for the sintering of Bi4Ti3O12 (BIT)-doped BaTi0.85Zr0.15O3 (BTZ) thick films, deposited by electro- phoresis, using as heating source a CO2 laser are presented. The thermal process associated to the laser scanning sintering (LSS) acted in a similar way as a two-step-sintering process. This characteristic together with the high heating rate al- lowed us to obtain thick films with an average grain size of 200 nm, high relative density (~96%) and with a homogene- ous microstructure. The X ray diffraction profile analysis show evidences for Bi 3+ replacing Ba 2+ at the A sites.

Superior Electrostrictive Strain Behavior of Antiferroelectric $({\rm Pb}, {\rm La})({\rm Zr}, {\rm Ti}){\rm O}_{3}$ Thick Film Microcantilevers for MEMS Device Applications

The microcantilevers based on the antiferroelectric (AFE) (Pb0.97La0.02)(Zr0.95Ti0.05)O3 (PLZT) thick films were fabricated by bulk silicon micromachining process. The conspicuous electrostrictive strain properties with phase transition of the AFE PLZT films induced by electric field were investigated. The resonant vibration velocity and tip deflection on a 650- μm-long cantilever were up to 6767 mm/s and 45.7 μm, under the square wave excitation with the voltage of 40 V, matched to the AFE-ferroelectric phase transition electric field of 210 kV/cm. The ratio of induced tip displacement and cantilever length per unit voltage [d(δ)/L/dV] was proposed to show the mutation response ability. In addition, the new AFE PLZT microcantilevers exhibited superior value of 10.77/kV, further higher than the traditional ones. Extensive application requirements for microdevices would be met in various fields of microelectromechanical systems.

Effect of Mn doping on structures and properties of chemical solution deposited lead zirconate titanate thick films with (100) preferential orientation

Mn doped PbZr0.52Ti0.48O3 (PZT) thick films with highly (100) preferential orientation have been prepared by chemical solution deposition according to doping concentration of 0, 0.5, 1, 2, and 3 mol. %. The effect of Mn-doping on structures and electrical properties of PZT thick films has been investigated. With increasing Mn doping concentration, the dielectric constant first increases and then decreases. PZT film with 0.5 mol. % Mn doping has a maximum value of 2252 and a dielectric loss of 0.011 at 1 kHz. Mn doping below 3 mol. % could effectively reduce the leakage current density of PZT films. The mechanism of Mn doping on dielectric and ferroelectric properties of PZT thick films has been investigated and discussed.

Thickness-dependent electrical properties of sol–gel derived Pb(Zr0.52Ti0.48)O3 thick films using PbTiO3 buffer layers

Pb(Zr0.52Ti0.48)O3 (PZT) thick films, with thickness up to 4 μm, using PbTiO3 (PT) buffer layers were successfully prepared on silicon-based substrates by a sol–gel method. Thermal analysis (thermogravimetric–differential thermal analysis) of PT and PZT sols were used to determine the pyrolysis and annealing temperatures. X-ray diffraction results show that the PZT/PT composite thick films possess perovskite structure and the dominant crystalline orientation changes from (100) to (110) with increasing the film thickness. Furthermore, the composite thick films exhibit thickness-dependent ferroelectric and dielectric properties, i.e., the coercive field decreases while dielectric constant increases as the thickness increases. Theoretical analysis shows that the thickness-dependent electrical properties are mainly attributed to the low dielectric constant of PT buffer layer and the relaxation of internal stress in PZT films.

Enhanced ferroelectric properties of highly (100) orientedPb(Zr0.52Ti0.48)O3thick films prepared by chemical solution deposition

Ferroelectric Pb ( Zr0.52Ti0.48) O3(PZT) thick films with highly (100) preferential orientation have been prepared by chemical solution deposition process on Pt / Ti / SiO2/(100) Si substrates and pyrolyzed at 350°C–450°C, then annealed at 650°C. The typical thickness of the films is 3.9 μm. Effects of the pyrolysis temperature and excess PbO on the orientation, dielectric and ferroelectric properties of PZT thick films have been discussed. Domain switching and depoling process were studied by piezoelectric force microscopy. (100) oriented PZT films exhibit enhanced electrical properties. The dielectric constant and loss tangent of the films are 1444 and 0.022 at 1 kHz, respectively. The remnant polarization increases from 27.6 to 34.6 μC/cm2, and the coercive field decreases from 61.4 to 43.5 kV/cm, when the orientation of the films changes from the random orientation to the preferential (100) orientation. The leakage current density is 10-8A/cm2at dc field of 0.25 kV/cm, and then increases to 10-6A/cm2at 40 kV/cm. The piezoelectric response of the oriented films is investigated by Piezoelecric Force Microscopy (PFM).

Synthesis and electrical properties of Pb(Zr0.52Ti0.48)O3 thick films embedded with ZnO nanoneedles prepared by the hybrid sol–gel method

Pb(Zr0.52Ti0.48)O3 thick films embedded with ZnO nanoneedles (PZT–ZnOn) were successfully prepared on Pt/Cr/SiO2/Si substrates by the hybrid sol–gel method via spin-coating ZnOn suspension and lead zirconate titanate (PZT) sol. To control the orientation of the films, a PbTiO3 (PT) layer was first deposited as a seed layer. Effects of annealing method and ZnOn contents on the corresponding orientation and crystallization of PZT–ZnOn films were investigated by XRD and SEM. The results show that all the PZT–ZnOn composite thick films have pure perovskite structure and high-quality film surface. The dielectric and ferroelectric properties of the PZT–ZnOn films are close to the PZT films, and have a little decrease with the increasing of the ZnOn contents.

Ag(Ta0.5Nb0.5)O3 Thick Film Based Microwave Band Pass Filters

We report on the simulated performance of a two–layered Microstrip and Coplanar Waveguide (CPW) band-pass filters by using one layer simulation method. The two layer is composed of Ag(Ta0.5Nb0.5)O3 (ATN) thick film and alumina substrate. The ATN thick film of about 7 μm in thickness is prepared by screen printing method on an alumina substrate of about 635 μm in thickness at a sintered temperature and time of 1150°C and 2 hrs, respectively. Au conductor of about 2 μm in thickness is deposited by sputtering method. The 2-pole band-pass filters are designed for a center frequency of 5.88 GHz, and 5.76 GHz with 7.8% and 8.6% bandwidth, respectively. Both ATN-based filters offer a similar selectivity as well as a loss parameter compared to that of two-layer simulation.

Performance of unimorph cantilever generator using Cr/Nb doped Pb(Zr0.54Ti0.46)O3 thick film for energy harvesting device applications

Abstract Structural and piezoelectric properties of Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt% Nb2O5 (PZT-CN) thick films were investigated for potential use in energy harvesting device applications. The PZT-CN thick films, fabricated by a conventional tape casting process, were successfully synthesized at a sintering temperature of 1100 °C. The sintered film exhibited excellent piezoelectric properties of d33 = 365 pC/N, e 33 T / e 0 = 1069 , and kp = 0.52. Its d33 · g33, which can characterize this material as a energy density material for energy harvesting device applications, was excellent, being as large as approximately 14,072 × 10−15 m2/N. It was also demonstrated that a unimorph cantilever using the PZT-CN film could generate a significant power of 17.3 mW (2083 μW/cm3) for high performance energy harvesters.

Effects of Bi2O3–Li2CO3 additions on dielectric and pyroelectric properties of Mn doped Pb(Zr0.9Ti0.1)O3 thick films

Pb(Zr0.9Ti0.1)O3 pyroelectric thick films adding various amounts of the sintering aids Bi2O3–Li2CO3 have been deposited on the substrates Al2O3 by the screen-printing process, and the dependence of microstructure, dielectric and pyroelectric properties on the content of sintering aids has been studied. When the amount of Bi2O3–Li2CO3 increases from 0 wt% to 5.4 wt%, the sintering temperature of the thick films decreases from 1100 °C to 900 °C, and the grain size and the lattice constant decrease either, but the density and the dielectric constant increase. The Pb(Zr0.9Ti0.1)O3 thick film with 5.4 wt% of Bi2O3–Li2CO3 sintered at 900 °C has the maximum pyroelectric coefficient 10.51×10−8 C/cm−2 K−1 and the highest figure-of-merit 10.58×10−5 Pa−0.5.

Effects of Li doping on dielectric properties of Ag(Ta0.5Nb0.5)O3 thick films

Abstract Low loss ferroelectric materials have been extensively investigated for the high frequency device applications. Especially, weak frequency dispersion materials with high dielectric permittivity and low loss tangent have enormous potential for electronic components including filters, and embedded capacitors. Ag(Ta 0.5 Nb 0.5 )O 3 thick films have been prepared by low temperature sintering aid Li 2 CO 3 (0, 1, 3 and 5 wt%). Ag(Ta 0.5 Nb 0.5 )O 3 thick films were characterized by X-ray diffraction analysis and scanning electron microscopy. The dielectric and ferroelectric properties were also investigated. We observed very weak frequency dispersion of dielectric permittivity at the microwave frequency range.