Effect of Ru and LaNiO3 barrier layers on lead zirconate titanate films grown on nickel-based metal foils by sol–gel process

Lead zirconate titanate [Pb(Zr_0.52, Ti_0.48)O₃ (PZT)] films were grown by sol–gel process on nickel and hastelloy foils. PZT perovskite phase was obtained at 650 °C annealing condition and surface topography showed uniform and dense microstructure. The characterization on dielectric properties indicates that diffusion of foil elements into the PZT and the formation of low capacitance interfacial layer occur during process. In order to reduce the diffusion effect of foil element and/or interfacial layer, barrier layers such as Ru(RuO₂) and LaNiO₃ layers were utilized on foil substrates. The increase of grain size was observed in PZT films grown on barrier layers. Dielectric properties are greatly improved without degrading ultimate dielectric breakdown strength.     

Combustion synthesis and electromagnetic properties of nanocrystalline Pb(Zr0.52Ti0.48)O3

The properties of nanocrystalline lead zirconate titanate [PZT, Pb(Zr_0.52Ti_0.48)O₃] thick films and pellets synthesized by self-propagating auto combustion route using sucrose as a fuel are reported. The X-ray diffraction reveals the formation of nanocrystalline tetragonal PZT having a particle size of 5.52 nm in thick films and 7.08 nm in bulk material. SEM images show the grain size of 300–400 nm with some agglomeration, as well as modified open grain boundaries and grain growth in the PZT thick film as compared to the bulk material. The DC electric resistivity of PZT shows semiconducting behavior. We also characterized the 8–18 GHz microwave insertion loss, absorption, complex permittivity, and microwave conductivity of synthesized materials. The real part of permittivity and dielectric loss were found to decrease with increasing frequency.     

Continuous ferrimagnetic Y3Fe5O12 layers on the ceramic PbZr0·45Ti0·55O3 substrates

For the first time, continuous layers of yttrium iron garnet (YIG, Y₃Fe₅O₁₂) with a thickness of about 2 μm were synthesized on ferroelectric ceramic substrates based on lead titanate zirconate (PZT, PbZr_0·45Ti_0·55O₃). The Y₃Fe₅O₁₂ layer was deposited by ion-beam sputtering – deposition on PZT substrates of 400 μm thick by sputtering a polycrystalline target of the composition Y₃Fe₅O₁₂ with a mixture of argon and oxygen ions. Due to preliminary planarization of the PZT surface with a TiO₂ layer, a high-quality plane-parallel YIG/PZT interface was obtained, which is confirmed by scanning electron microscopy in combination with the focused ion beam technique. Atomic force microscopy showed that planarization makes it possible to achieve surface smoothness of 10 nm.The YIG/PZT heterostructures obtained in this work are potentially attractive for use in logic circuits based on low-scattering spin waves, memory elements, as well as electrically controlled microwave devices.     

PZT thick films on LTCC substrates with an interposed alumina barrier layer

PZT thick films (PbZr_0.53Ti_0.47O₃ with the addition of 6% PbO and 2% Pb₅Ge₃O₁₁) with a low sintering temperature were printed and fired on LTCC substrates (951, Du Pont), covered with an alumina barrier layer. The electrical characteristics (remanent polarisation, coercive field, dielectric constant and dielectric loss) of these PZT thick films, together with sets prepared on “unprotected” LTCC substrates and on alumina substrates were compared. Whereas the electrical characteristics of the films on LTCC substrates deteriorated significantly due to interactions between the LTCC substrates and the PZT layers the values obtained for the LTCC/alumina barrier structures were comparable with those on ceramic alumina substrates.     

Effect of neodymium substitution on crystalline orientation,microstructure and electric properties of sol-gel derived PZT thin films

Pb(Nd_xZr_0.52Ti_0.48)O₃ (PNZT) (x = 0%, 1%, 2%, 3%, 4%, 5%) thin films were prepared by sol-gel process to investigate the effects of neodymium substitution on crystalline orientation, microstructure and electric properties of lead zirconate titanate (PZT) films. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis showed that PNZT films with Nd doping concentration below 3% exhibited dense perovskite structure with (100) preferred orientation. The average grain size of PNZT films decreased as the Nd substitution increased. The maximum dielectric constant, remnant polarization and minimum coercive field were obtained in 2% Nd-doped PZT films. Fatigue resistance was also improved significantly with 2% Nd dopant.     

Piezoelectric Properties of a Pioneering 3‐1 Type PZT/Epoxy Composites Based on Freeze‐Casting Processing

Lead zirconate titanate (PbZr_1 ? xTi_xO₃, PZT)/epoxy composites with one‐ dimensional epoxy in PZT matrix (called 3‐1 type piezocomposites) have been fabricated by tert‐butyl alcohol (TBA)‐based directional freeze casting of PZT matrix and afterward infiltration of epoxy. The composites with PZT volume fraction ranging from 0.36 to 0.69 were obtained by adjusting initial solid loading in freeze‐casting slurry. The effect of poling voltage on piezoelectric properties of the composites was studied for various volume fraction of PZT phase. With the increasing of PZT volume fraction, relative permittivity (ε_r) increased linearly and piezoelectric coefficient (d₃₃ and d₃₁) increased step by step. The resultant composites with 0.57 PZT volume fraction possessed the highest hydrostatic piezoelectric strain coefficient (d_h) value (184 pC/N), voltage coefficient (g_h) value (13.6 × 10^?3 V/m Pa), and hydrostatic figure of merit (HFOM) value (2168 × 10^?15 Pa^?1).     

Low temperature chemical synthesis of nanosized ceramic powders

Abstract

A variety of nanosized (particle dia. <100 nm) ceramic powders have been prepared from metal ion complex based precursor solutions. The precursor solution was prepared at room temperature from metal hydroxides, nitrates, or acetates mixed with suitable complexing agents such as amines, carboxylic acids, hydroxy carboxylic acids, or poly-hydroxy compounds. Calcination of the precursor mass at low external temperatures produces the nanosized ceramic powders. The examples discussed include perovskites, i.e. lead zirconate titanate PbZr_0·6 Ti_0·4O₃(PZT) and lead magnesium niobate PbMg_1/3 Nb_2/3 O₃ (PMN).     

Polydimethylsiloxane–PbZr0.52Ti0.48O3 nanocomposites with high permittivity: Effect of poling and temperature on dielectric properties

Polydimethylsiloxane (PDMS)/lead zirconate titanate (PbZr_0.52Ti_0.48O₃, PZT)-based nanocomposites with high dielectric constant (permittivity, k) are prepared through room temperature mixing. The effect of PZT loading on electrical and mechanical properties of the PDMS–PZT composites is extensively studied. It is found that there is significant increase in permittivity with PZT loading and decrease in volume resistivity. All the composites have low dielectric loss compared to permittivity value. It is observed that there is increase in permittivity and decrease in volume resistivity of composites after poling, which is due to the dipolar polarization. It is found that both permittivity (ε′) and alternating current conductivity (σ_ac) are increased with temperature at low frequency (1 Hz) and decreased with temperature at high frequency (1 MHz). The above composites are sensitive to external pressure and can be used as pressure/force sensor. The tensile strength and % elongation at break decreases with PZT loading, which is due to the nonreinforcing behavior of PZT ceramic. PZT particles distribution and dispersion in PDMS matrix are observed through field emission scanning electron microscopy, high resolution transmission electron microscopy, and atomic force microscopy/scanning probe microscopy. Thermal stability of composites increased with the PZT loading which is due to higher thermal stability of PZT particles compared to PDMS matrix. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47307.     

Temperature dependence of field‐responsive mechanisms in lead zirconate titanate

An electric field loading stage was designed for use in a laboratory diffractometer that enables in situ investigations of the temperature dependence in the field response mechanisms of ferroelectric materials. The stage was demonstrated by measuring PbZr_1?xTi_xO₃ (PZT) based materials—a commercially available PZT and a 1% Nb‐doped PbZr_0.56Ti_0.44O₃ (PZT 56/44)—over a temperature range of 25°C to 250°C. The degree of non‐180° domain alignment (η₀₀₂) of the PZT as a function of temperature was quantified. η₀₀₂ of the commercially available PZT increases exponentially with temperature, and was analyzed as a thermally activated process as described by the Arrhenius law. The activation energy for thermally activated domain wall depinning process in PZT was found to be 0.47 eV. Additionally, a field‐induced rhombohedral to tetragonal phase transition was observed 5°C below the rhombohedral‐tetragonal transition in PZT 56/44 ceramic. The field‐induced tetragonal phase fraction was increased 41.8% after electrical cycling. A large amount of domain switching (η₀₀₂=0.45 at 1.75 kV/mm) was observed in the induced tetragonal phase.     

Direct processing of PbZr0.53Ti0.47O3 films on glass and polymeric substrates

This work reports on direct crystallization of PbZr_0.53Ti_0.47O₃ (PZT) thin films on glass and polymeric substrates, using pulsed thermal processing (PTP). Specifically, xenon flash lamps deliver pulses of high intensity, short duration, broadband light to the surface of a chemical solution deposited thin film, resulting in the crystallization of the film. Structural analysis by X-ray diffraction (XRD) and transmission electron microscopy show the existence of perovskite structure in nano-sized grains (≤5 nm). Local functional analysis by band excitation piezoelectric spectroscopy and electrostatic force microscopy confirm the presence of a ferroelectric phase and retention of voltage-written polarization for multiple days. Based on structural and functional analyses, strategies are discussed for optimization of pulse voltage and duration for the realization of crystalline ferroelectric thin films. For ∼200 nm-thick PZT films on glass substrates, 500 μs-long pulses were required for crystallization, starting with 100 pulses at 350 V, 10 or 25 pulses at 400 V and in general lower number of pulses at higher voltages (resulting in higher radiant energy). Overall power densities of >6.4 kW/cm² were needed for appearance of peaks corresponding to the perovskite phase in the XRD. Films on glass processed at 350–400 V had a higher degree of 111-oriented perovskite grains. Higher applied radiant energy (through increased pulse voltage or count) resulted in more random and/or partially 001-oriented films. For ∼1 μm-thick PZT films on polymeric substrates, 10 to 25 250 μs-long pulses at voltages ranging between 200 to 250 V, corresponding to power densities of ∼2.8 kW/cm², were optimal for maximized perovskite phase crystallization, while avoiding substrate damage.     

Voltage effect of corona poling on characteristics of PbZrxTi1−xO3 (PZT) film

The paper investigates the voltage effect of corona poling on the characteristics of PbZr_xTi_1−xO₃ (PZT) thin film. Purchased PZT powder and lab-made PZT solution were mixed together as sol-gel that was spin-coated on titanium (Ti) substrate. X-ray diffractometer (XRD), scanning electron microscopy (SEM), impedance analyzer were utilized to measure the orientation and dielectric characteristics of films for comparison. The experimental results indicated that the poling voltage would not affect the orientation of crystallization, microstructure and grain size of PZT film surface. However, the higher applied poling voltage would result in better charge storage capacity and energy transfer efficiency of the film.     

Influences of Liquid‐Phase Sintering on Structure,Grain Growth,and Dielectric Behavior of PbZr0.52Ti0.48O3 Ceramics

In this work, to formulate piezoceramic systems such as PbZr_0.52Ti_0.48O₃ (PZT) for low‐temperature co‐fired ceramic (LTCC)‐based devices, liquid‐phase sintering approach is demonstrated. ZnO–B₂O₃ (ZB) binary glass system is used as sintering aid. X‐ray diffraction (XRD) study confirms the formation of morphotropic phase boundary (MPB; tetragonal + rhombohedral) in PZT prepared by hydrothermal route. ZB is found to induce change in tetragonal/rhombohedral ratio in MPB of PZT. 1%ZB in PZT is found to raise the tetragonality from 71% to 92% in MPB region of PZT. ZB addition in PZT has reduced the sintering temperature from 1250 to 825°C for relative density about 91% with sustaining MPB phase. 1% ZB content is optimal percentage to enhance sinterability and relative density. Uniform dispersion of glass in PZT matrix is confirmed by SEM images. ZB content in PZT is found to controlling grain growth during sintering. Highest dielectric constant and lowest dielectric loss with low sintering temperature (825°C) of 1%ZB among all glass added in PZT exhibit technical suitability of 1%ZB + PZT to use as LTCC‐based energy storage devices.     

Oxygen plasma-assisted ultra-low temperature sol-gel-preparation of the PZT thin films

PbTi_1-xZr_xO₃ (PZT) thin films prepared by sol-gel method have paid much attention due to the excellent performances in piezoelectric, dielectric, ferroelectric and electro-optical. However, the high crystallization temperature of the PZT thin films restricts the compatibility with modern COMS technology. In this work, PbZr_0.52Ti_0.48O₃ (PZT) ferroelectric thin films were successfully prepared by sol-gel method at an ultra-low temperature (～450 °C) in an oxygen plasma-assisted environment. A large spontaneous polarization ～30 μC/cm² and a large dielectric breakdown ～2,900 kV/cm were obtained in the sample annealed at 450 °C for 25 h. We believe that the oxygen plasma-assisted ultra-low temperature (OPAULT) annealing process is a promising way for the sol-gel technology applied in the modern COMS devices.     

PbZr0.4Ti0.6O3 dielectric reflectors with large photonic band gap and high average optical reflectivity

PbZr_0.4Ti_0.6O₃ multilayer, comprising of three PbZr_0.4Ti_0.6O₃ stacks with a slight difference in their periodic thickness, has been designed and fabricated on FTO substrate based on one single chemical solution and on the simple spinning‐coating and annealing technique. The obtained multilayer exhibits a high reflectivity band with 110 nm photonic stop‐band width and average reflectivity of over 80% at room temperature, rendering the novel arrange of PbZr_0.4Ti_0.6O₃ multilayer system a promising candidate as tunable dielectric mirrors, optical cavities and selective filters.     

Phase and Texture Evolution in Chemically Derived PZT Thin Films on Pt Substrates

The crystallization of lead zirconate titanate (PZT) thin films was evaluated on two different platinum‐coated Si substrates. One substrate consisted of a Pt coating on a Ti adhesion layer, whereas the other consisted of a Pt coating on a TiO₂ adhesion layer. The Pt deposited on TiO₂ exhibited a higher degree of preferred orientation than the Pt deposited on Ti (as measured by the Full Width at Half Maximum of the 111 peak about the sample normal). PZT thin films with a nominal Zr/Ti ratio of 52/48 were deposited on the substrates using the inverted mixing order (IMO) route. Phase and texture evolution of the thin films were monitored during crystallization using in situ X‐ray diffraction at a synchrotron source. The intensity of the Pt₃Pb phase indicated that deposition on a highly oriented Pt/TiO₂ substrate resulted in less diffusion of Pb into the substrate relative to films deposited on Pt/Ti. There was also no evidence of the pyrochlore phase influencing texture evolution. The results suggest that PZT nucleates directly on Pt, which explains the observation of a more highly oriented 111 texture of PZT on the Pt/TiO₂ substrate than on the Pt/Ti substrate.     

Rapid Microwave Annealing of Amorphous Lead Zirconate Titanate Thin Films Deposited by Sol‐Gel Method on LaNiO3/SiO2/Si Substrates

The heating behavior of LaNiO₃ (LNO) films on SiO₂/Si substrate heated by 2.45 GHz microwave irradiation in the microwave magnetic field was first investigated, and then amorphous Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films were deposited on LNO‐coated SiO₂/Si substrates by a sol‐gel method and crystallized in the microwave magnetic field. The crystalline phases and microstructures as well as the electrical properties of the PZT films were investigated as a function of the elevated temperature generated by microwave irradiation. The perovskite PZT films with a highly (100)‐preferred orientation can be obtained by microwave annealing at 700°C for only 180 s of total processing time, and have good electrical properties. The results demonstrated that conductive metal oxide LNO as a bottom electrode layer is an advantage for the crystallization of PZT thin films by microwave irradiation in the microwave magnetic field.     

Growth of thin film ferroelectric PZT,PHT, and antiferroelectric PHO from atomic layer deposition precursors

We present a conformal method of growing ferroelectric lead hafnate-titanate (PbHf_xTi_1−xO₃, PHT) and lead zirconate-titanate (PbZr_xTi_1−xO₃, PZT) using atomic layer deposition (ALD) precursors. The 4+ cation precursors consist of tetrakis dimethylamino titanium (TDMAT), tetrakis dimethylamino zirconium (TDMAZ) and tetrakis dimethyl amino hafnium (TDMAH) for Ti, Zr, and Hf, respectively. The Pb (2+) precursor was Lead bis(3-N,N-dimethyl-2-methyl-2-propanoxide) [Pb(DMAMP)₂]. PZT was limited to lead titanate (PTO)-rich compositions, where x <0.25 for PbZr_xTi_1−xO₃, and exhibited a remnant polarization of 26-27 µC/cm² with a coercive field between 150 and 170 kV/cm. The 3D-structure coating capability of PZT was demonstrated by deposition on micromachined trench sidewalls 45 µm deep. We fabricated Microelectromechanical systems (MEMS) cantilever arrays with PZT thin films grown using the present method and demonstrated piezoelectric actuation. Alternatively, PHT was deposited with Ti and Hf compositions within ±1 at.% of the morphotropic phase boundary (MPB). The PHT exhibited a remanent polarization of 7.0-8.7 µC/cm² with a coercive field between 84-100 kV/cm. We applied the same Pb and Hf precursors from the PHT process to grow antiferroelectric lead-hafnate (PHO), which showed the characteristic electric field-induced ferroelectric phase transition at approximately ±280 kV/cm and a maximum polarization of approximately ±32.8 µC/cm².     

Effect of Switching Atmospheric Conditions during Crystallization on the Phase Evolution of Solution‐Derived Lead Zirconate Titanate Thin Films

The crystallization behavior of solution‐derived lead zirconate titanate (PZT) thin films in different atmospheric environments was studied using in situ X‐ray diffraction. The stability of the transient intermetallic Pt₃Pb phase and perovskite PZT is dependent on oxygen partial pressure during crystallization. Based on the relationship between oxygen partial pressure and the resultant phase stability of intermediate phases, a new route to produce PZT thin films was developed. The new route involves switching atmospheres during crystallization and is shown to mitigate the formation of the transient intermetallic Pt₃Pb phase and to promote the perovskite PZT phase. The route evidences a new and significant variable controlling film synthesis and film microstructure.     

Laser sintered ceramic coatings of PZT nanoparticles deposited by Inkjet Printing on metallic and ceramic substrates

Lead zirconate titanate (PZT) Pb(ZrxTi1-x)O₃ is one of the most studied perovskite type ferroelectric materials due to its excellent dielectric, piezoelectric and ferroelectric properties. PZT particles and a PZT precursor were synthesized using a chemical method. A vehicle was added to the synthesized particles and precursor for obtaining two inks with appropriate rheological properties to be printed by Inkjet Printing. The use of an 80?µm diameter nozzle made necessary the utilization of an energetic ball milling for assuring the dispersion of small PZT particles in the ink. After ball milling nanoparticles of 150?nm diameter were obtained. These inks were deposited on alumina and steel substrates followed by sintering using a pulsed laser of 1064?nm wavelength. The work shows the effect laser sintering has on, both inks, the one containing PZT nanoparticles and that one based on the PZT precursor. Laser processing was optimized in order to generate suitable films to be subsequently poled. The effect of poling on these films was also studied and their piezoelectric properties were measured by a compression test. The microstructural characteristics of these films were obtained by SEM and X ray diffractometry.     

Role of the PbTiO3 Seed Layer on the Crystallization Behavior of PZT Thin Films

The role of a highly crystalline and oriented lead titanate (PTO) seed layer on the subsequent phase and texture evolution of lead zirconate titanate (PZT) thin films is investigated in situ using X‐ray diffraction (XRD) during crystallization. Crystalline PTO seed layers were first prepared via a 2‐methoxyethanol route. Amorphous PZT with a Zr/Ti ratio of 52/48 was then deposited on the seed layer using the same synthesis route and subsequently crystallized in situ during XRD. During heating, a tetragonal‐to‐cubic transformation of the seed layer occurs prior to the formation of perovskite PZT. Subsequent nucleation of the crystalline PZT occurs in the cubic phase. Simultaneous to nucleation of PZT, development of a dominant 100 texture component was observed in the PZT phase of the thin films. The results indicate that 100 textured PTO nucleates 100 texture of PZT thin films during crystallization.