Ceramic Thick Films Research Articles

Boosting the Recoverable Energy Density of Lead-Free Ferroelectric Ceramic Thick Films through Artificially Induced Quasi-Relaxor Behavior.

Dielectric ceramic film capacitors, which store energy in the form of electric polarization, are promising for miniature pulsed power electronic device applications. For a superior energy storage performance of the capacitors, large recoverable energy density, along with high efficiency, high power density, fast charge/discharge rate, and good thermal/fatigue stability, is desired. Herein, we present highly dense lead-free 0.942[Na0.535K0.480NbO3]-0.058LiNbO3 (KNNLN) ferroelectric ceramic thick films (∼5 μm) demonstrating remarkable energy storage performance. The nanocrystalline KNNLN thick film fabricated by aerosol deposition (AD) process and annealed at 600 °C displayed a quasi-relaxor ferroelectric behavior, which is in contrast to the typical ferroelectric nature of the KNNLN ceramic in its bulk form. The AD film exhibited a large recoverable energy density of 23.4 J/cm3, with an efficiency of over 70% under the electric field of 1400 kV/cm. Besides, an ultrahigh power density of 38.8 MW/cm3 together with a fast discharge speed of 0.45 μs, good fatigue endurance (up to 106 cycles), and thermal stability in a wide temperature range of 20-160 °C was also observed. Using the AD process, we could make a highly dense microstructure of the film containing nano-sized grains, which gave rise to the quasi-relaxor ferroelectric characteristics and the remarkable energy storage properties.

Microwave dielectric properties of barium substituted screen printed CaBi2Nb2O9 ceramic thick films

In the present study, Aurivillius-structured Ba2+ substituted CaBi2Nb2O9 (CBNO) ceramic powder was synthesized by co-precipitation method. The CBNO thick films were delineated by screen printing method on alumina substrates using co-precipitated ceramic powder. The overlay method was adopted to measure the microwave dielectric properties of prepared thick films. Single phase layered perovskite structure of the prepared thick films was confirmed by X-ray Diffraction. The effects of Ba2+ substitution on the surface morphology, bonding, and microwave dielectric properties of thick films were systematically presented. The maximum value of microwave dielectric constant for the CBNO thick films at 11.8GHz is 15.6 for Ba2+=0.8 substitution. The shift in the stretching vibration modes of the Nb-O bond of NbO6 octahedron in the Raman spectra with a substitution of Ba2+ in CBNO was observed. The substitution of Ba2+ on A-site of CBNO improves the microwave dielectric properties of prepared thick films. This work may provide a new approach to enhance the microwave dielectric performance of Aurivillius-structured ceramic thick films.

Large electrocaloric effect in lead-free Ba(ZrxTi1-x)O3 thick film ceramics

Barium zirconate titanate (Ba(ZrxTi1-x)O3) thick film ceramics were prepared using a tape-casting method. Their structures, morphologies, and electric properties were characterized using XRD, SEM and impedance analysis approaches, respectively. The electrocaloric effects (ECE), i.e., isothermal entropy changes and adiabatic temperature changes, were calculated using a Maxwell relation. It was confirmed by XRD and SEM that the obtained thick film ceramics are pure and dense perovskite structures. The dielectric analyses indicate that the Ba(ZrxTi1-x)O3 thick film ceramics show characteristics of transition from normal to relaxor ferroelectrics with the increasing Zr4+ ionic content. The polarization – electric field (P-E) hysteresis loops reveal larger polarizations and the ceramics can withstand an electric field as high as 12 MV/m. The adiabatic temperature changes ΔT calculated via the Maxwell relation and the polarization as a function of temperature, which is extracted from the P-E hysteresis loops measured at 12 MV m−1 are from 3.7 to 0.28 K with the increasing Zr4+ ionic content.

Development of Fullerene Modified Metal Oxide Thick Films for Moisture Sensing Application

Trace moisture sensing capability of fullerene (C60) modified nanoporous γ-alumina (Al2O3) thick films has been presented here. Fullerene was added to create nano pore in aluminum secondary butoxide for preparation of gel tape cast thick films. One of the major advantages of using fullerene is to develop oriented nano pores (2-12 nm) throughout the ceramic thick films. The green thick films were crack free which was cast by gel tape casting process. The porosity and surface area were studied using field effect scanning electron microscope, atomic force microscope and Brunauer–Emmett–Teller. Gamma phase of alumina was also examined by X-ray diffraction analysis. The green thick films were sintered at 900 °C to obtain nanopore distribution through the surface of the thick films. Electrical characterization such as sensitivity, response, recovery and hysteresis were performed. There is no literature report on the detection of trace moisture sensor by fullerene assisted alumina sol gel tape cast process. This article explains the development of moisture sensor which can detect low range moisture (1-25 ppm) in different industrial application like gas industry, dielectric oil and drying of different food processing industry etc.

Giant electrocaloric effect of free-standing Pb0.85La0.1(Zr0.65Ti0.35)O3 thick films fabricated by the self-lift-off screen printing method

Free-standing Pb0.85La0.1(Zr0.65Ti0.35)O3 (PLZT) ceramic thick films have been prepared via a facile and low-cost self-separating screen printing method for electrocaloric cooling, and the relation among the fabrication processes, phase composition, microstructure, dielectric characteristics, ferroelectric properties and electrocaloric effect (ECE) has been systematically investigated. Compared to the conventional ceramic thick films supported by substrates, the free-standing feature enables the EC cooling of the free-standing PLZT thick films to be fully used for cooling down different thermal loads rather than be futilely absorbed by the substrates. Furthermore, without the mechanical restriction of the substrates, the free-standing PLZT thick films can freely shrink during the high-temperature densification process, leading to their high density and favorable microstructures. Additionally, by introducing an adequate amount of excess PbO, the pyrochlore phase can be removed from the samples to yield high-purity perovskite PLZTs. With the comprehensive improvement in phase composition, microstructure and the elimination of mechanical strain between the active materials and substrates, the free-standing PLZT thick films exhibited an optimized ECE including changes of temperature and entropy of 1.95°C and 2.09Jkg−1K−1, which are almost 3 times that of the samples deposited on the Al2O3 substrates without excess PbO. This work would contribute to the development of ferroelectric ceramics, especially thick films, for practical EC cooling.

Mode‐matching analysis of a spit‐circular cavity resonator for measurement of the dielectric constant for film on a substrate

In this paper, we apply the mode‐matching technique (eigenmode expansion) to formulate an analytical model for a split cylindrical cavity resonator with a thick ceramic film layer sandwiched between two‐layer alumina substrates. We then compute the resonant frequencies with the TE011 mode with an eigenvalue problem approach using the model formula. The quality factor (Q‐factor) of the resonator is also calculated by applying the perturbation method to the analytical model. The validity of the proposed analytical technique is confirmed by applying this method to the estimation of permittivity of thick films as an inverse problem. Ceramic films (2 µm thickness) were synthesized using a chemical solution method onto 200‐µm‐thick, 50‐mm‐diameter alumina substrates. The complex permittivity of the films was then determined using the TE011 mode split cylindrical cavity resonator in the 10‐GHz band. The extent of the edge effect at a sample insertion space was evaluated by comparing the estimated results through TE wave analysis using the mode‐matching method when the transverse resonance technique and the perturbation method were applied to calculate the resonant frequency and the dielectric Q‐factor. The results obtained indicate that a difference of 0.153% in the permittivity of the alumina substrate causes differences of 6.10 and 3.75% in the measured permittivity and loss tangent, respectively, of 2‐µm‐thick ceramic film with a permittivity of ∼50. Differences in permittivity and loss tangent were more pronounced with thinner films. It was also confirmed that the estimated results for permittivity and the loss tangent values of these ceramic films were affected by the estimated permittivity value of the alumina substrate. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Optimizing inkjet printing process to fabricate thick ceramic coatings

This article describes the use of Taguchi optimization and ANOVA techniques on inkjet printing process to determine optimal parameters for fabrication of thick ceramic coatings over glass substrates. Stable nanoparticle suspensions are synthesized through high energy milling of precursor powders with adequate quantities of binder and suspending solvent. Most often, inkjet printing process is being used for developing fine and thin layers (<10µm). However, an attempt is made to fabricate thick ceramic films by varying only IJP process parameters and without multiple layer deposition, thereby reducing efforts in ink synthesis and processing time of coated substrates. Three parameters of IJP were varied for developing a model that was used for precisely predicting the printed layer thickness under varying process parameters. ANOVA technique showed that open time interval in combination with nano particle concentration in the ink could potentially lead to thick coatings. The higher volume % of solvent in the diluted suspension ink under the influence of substrate heating contributed significantly to coffee stain effect with irregular surface coatings. However, increasing the concentration of nanoparticles in the diluted ink resulted in substantial improvement in thickness of the layer with simultaneous control of coating defects.

Aerosol Method for Room Temperature Thick-Film Deposition

Abstract Aerosol deposition offers an alternative to conventional thin film processes when mesoscale coatings are needed. The process is being used to create readily integrated, high density ceramic and metallic thick films on a variety of substrates at room temperature.

Adaption of Functional Ceramic Materials for the Laser Sintering Process in Integrated Sensor Applications

The ceramic thick film technology allows the buildup of miniaturized and robust integrated multilayer circuits and sensors by means of sequential screen printing and firing of different functional materials. However, the manufacturing of integrated electronics does not succeed if the components are temperature sensitive or too large for the process in a sintering furnace. At present, large components like wind power rotors, axles, or roller bearings are monitored by vulnerable hybrid sensor systems. To implement the advantages of integrated devices, such as the direct surface contact and the high thermomechanical stability, functional ceramic-based materials are adapted or newly developed to accommodate the requirements of laser sintering techniques of printed sensor layers on structural components. In a first approach, first screen-printed thick films on steel components are investigated. The defect-free densification of functional layers crucially depends on the particular material composition and adapted laser treatment. A first generation of functional layers is presented, comprising insulating, conductive, and resistive electrical materials. The films are tested in demonstrator setups and show functional properties comparable with those of the furnace sintering technology. Herein, future aspects of material optimization and the adaption to specific application requirements are discussed.

An Implantable Intravascular Pressure Sensor for a Ventricular Assist Device.

The aim of this study is to investigate the intravascular application of a micro-electro-mechanical system (MEMS) pressure sensor to directly measure the hemodynamic characteristics of a ventricular assist device (VAD). A bio- and hemo-compatible packaging strategy is implemented, based on a ceramic thick film process. A commercial sub-millimeter piezoresistive sensor is attached to an alumina substrate, and a double coating of polydimethylsiloxane (PDMS) and parylene-C is applied. The final size of the packaged device is 2.6 mm by 3.6 mm by 1.8 mm. A prototype electronic circuit for conditioning and read-out of the pressure signal is developed, satisfying the VAD-specific requirements of low power consumption (less than 14.5 mW in continuous mode) and small form factor. The packaged sensor has been submitted to extensive in vitro tests. The device displayed a temperature-independent sensitivity (12 V/V/mmHg) and good in vitro stability when exposed to the continuous flow of saline solution (less than 0.05 mmHg/day drift after 50 h). During in vivo validation, the transducer has been successfully used to record the arterial pressure waveform of a female sheep. A small, intravascular sensor to continuously register the blood pressure at the inflow and the outflow of a VAD is developed and successfully validated in vivo.

저온 소결 조제에 따른 PMN-PZ-PT 후막 세라믹 특성

저온 소결 조제에 따른 PMN-PZ-PT 후막 세라믹 특성

Additive Manufacturing Design and Fabrication of Ceramic Cylindrical Ion Trap Mass Analyzer Chips for Miniaturized Mass Spectrometer Smart-Device (Internet of Things) Applications

The current computing power and network capabilities of handheld smart devices is helping to drive the development of new sensors, enabling the Internet of things. A chip-based mass spectrometer technology promises to offer a smart-device autonomous microsystem chemical analysis capability for sample determination and process monitoring for multiple applications in a small low-power instrument package. This project focuses on the development of cylindrical ion trap (CIT) mass analyzer chips fabricated using three-dimensional (3-D) additive manufacturing (AM) and planar low temperature cofired ceramic thick film processes for a chip-based mass spectrometer microsystem. The CIT is a mass analyzer composed of planar electrodes and operates by trapping and ejecting sample ions based on their mass in a radiofrequency field. Because of its simplicity, CITs may be easily miniaturized and connected in tandem to achieve multiplexing. AM materials and methods enable enhanced trap miniaturization through micromachining and electrode patterning methods, fast and cost-effective prototyping, batch fabrication, and material formulation flexibility. The current design incorporates three parallel ceramic plate metalized electrodes making up a singular trap geometry in a 10-mm2 ceramic chip, forming a mass analyzer of reduced size, mass, and power, with enhanced material robustness for extended range use and in harsh environments. Unique processes have been developed to produce these devices which include conformal metallization layers, adhesion layers, ceramic paste formulations, sacrificial supporting materials, and cofiring methods. Additionally, 3-D printing brings a unique design and fabrication capability enabling novel structures, material blending, and heterogeneous integration. With true digital control, the designs are easily scalable and shape agnostic.

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Crack‐Free Drying of Ceramic Microparts on a Hydrophobic Flexible Polymer Substrate Using Soft Lithography

Drying is a critical step in the fabrication of ceramic microparts from suspensions using soft lithography. In this communication, a simple method using a hydrophobic flexible polymer substrate was demonstrated to avoid the formation of cracks within ceramic microparts. Crack‐free alumina green microchannel parts with 120 μm feature size were attained on a polyethylene film. The results show that both the hydrophobic and flexible properties of the polymeric substrates can remove the substrate constraint to the green body of micropart, which is capable of preventing cracks formation. The method can be used to fabricate ceramic microparts/micropatterns for microeletromechanical systems and functional thick ceramic films.

Structural, electrical and microwave properties of (Sr0.6Ca0.4) (CoyMn1−y) O3 (0.2 ≤ y ≤ 1.0) thick film ceramics

Purpose – This paper aims to study the structural, electrical and microwave properties of (Sr0.6Ca0.4) (CoyMn1−y) O3 (0.2 ≤ y ≤ 1.0) thick-film ceramics. Design/methodology/approach – The thick films of (Sr0.6Ca0.4) (CoyMn1−y) O3 (0.2 ≤ y ≤ 1.0) on the alumina substrate have been delineated using screen printing technique. The structural analysis was carried out using an X-ray diffraction method and scanning electron microscopy. The direct current (DC) electrical resistivity is measured using a two-probe method. Microwave absorption was studied in the 8-18 GHz frequency range by using the Waveguide Reflectometer Method. The permittivity and permeability in the 8-18 GHz frequency range were measured by using Voltage Standing Wave Ratio slotted section method. Findings – The thick films have orthorhombic perovskite structure with dominant (020) plane. By using first-principle calculation method, theoretical and experimental lattice parameter and cell volume of (Sr0.6Ca0.4) (CoyMn1−y) O3 are matched with each other. The cobalt content changes the morphology from plates to needles. The DC electrical resistivity increases with increase in Co content and decreases with increase in temperature. (Sr0.6Ca0.4) (CoyMn1−y) O3 thick film shows 75 per cent microwave absorption both in the X band and Ku band. The microwave permittivity and permeability decreases with increase in frequency and Co content. Originality/value – Structural, electrical and microwave properties of (Sr0.6Ca0.4) (CoyMn1−y) O3 (0.2 ≤ y ≤ 1.0). Thick film ceramics on alumina substrate is reported for the first time.

Additive Manufacturing Design and Fabrication of Ceramic Cylindrical Ion Trap Mass Analyzer Chips for Miniaturized Mass Spectrometer Smart-Devices

A chip based mass spectrometer technology promises to offer smart-device autonomous microsystem chemical analysis capability for sample determination and process monitoring for multiple applications in a small low power instrument package. This project focuses on the development of cylindrical ion trap mass analyzer chips fabricated using 3D Additive Manufacturing and planar Low Temperature Co-Fired Ceramic thick film processes toward the realization of a chip based mass spectrometer microsystem. The cylindrical ion trap (CIT) is a mass analyzer comprised of planar electrodes and operates by trapping and ejecting sample ions based on their mass in an RF field. Because of its simplicity CITs may be easily miniaturized and connected in tandem to achieve multiplexing. Additive manufacturing materials and methods enable enhanced trap miniaturization through micro machining and electrode patterning methods, fast and cost effective prototyping, batch fabrication, and material formulation flexibility. The current design incorporates three parallel ceramic plate metalized electrodes making up a singular trap geometry in a 10mm2 ceramic chip, forming a mass analyzer of reduced size, mass, and power, with enhanced material robustness for extended range use and in harsh environments. Unique processes have been developed to produce these devices which include conformal metallization layers, adhesion layers, ceramic paste formulations, sacrificial supporting materials, and co-firing methods. Additionally, 3D printing brings a unique design and fabrication capability enabling novel structures, material blending and heterogeneous integration. With true digital control, the designs are easily scalable and shape agnostic.

Anode-supported Type SOFCs based on Novel Low Temperature Ceramic Coating Process

To prevent an interfacial reaction between the anode and the electrolyte layer during the conventional high-temperature co-firing process, an anode-supported type cell with a thin-film electrolyte was fabricated by low-temperature ceramic thick film coating process. Ni-GDC cermet composite was used as the anode material and YSZ was used as the electrolyte material. Open circuit voltage and maximum power density were found to strongly depend on the surface uniformity of the anode functional layer. By optimizing the microstructure of the anode functional layer, the open circuit voltage and maximum powder density of the cell increased to 1.11 V and 1.35 W/㎠, respectively, at 750℃. When a GDC barrier layer was applied between the YSZ electrolyte and the LSCF cathode, the cell showed good stability, with almost no degradation up to 100 h. Anode-supported type SOFCs with high performance and good stability were fabricated using a coating process.

Advances in Microscale and Nanoscale Mechanisms of Electrophoretic Deposition in Aqueous Media

The processing of ceramic thick and thin films, nano- and micro-scaled ceramic structures as well as bulk ceramics of high quality and precise dimensions under electrophoretic boundary conditions requires a full understanding of the dynamics of relevant interfacial mechanisms and interactions of colloidal phases at the nano- and micro-scale. Recent findings and latest insights on the importance of electrokinetic and electrohydrodynamic interfacial processes for membrane electrophoretic depositon in aqueous media are summarised. In this context, the paper addresses the fundamental importance of surficial charge heterogeneities, electric double layer instabilities, electrokinetically induced micro-vortex dynamics, as well as lateral and medial effective electrical field gradients. These phenomena are evaluated in terms of reasonable correlations and mechanistic coincidences of general EPD deposition principles. The experimental results are based on potentiometry, in-situ videomicroscopy, high-resolution as well as secondary electron microscopy. A numerical method for the simulation of the electrophoretic deposition process is suggested based on a multiphysical Finite Element approach given by Nernst-Planck, Poisson- and Navier-Stokes equations. The results of the simulations provide adequate agreement with experimental findings.

Numerical calculation of temperature and surface topology during a laser ablation process for ceramic coatings

In this paper a numerical procedure is presented to calculate a laser ablation process for ceramic thick film coatings. The code is required to cover temperature dependent material data, projected beam intensities and inhomogeneous coating–substrate combinations to calculate the hole shape geometry, the temperature distribution under the surface and the ablation rate per pulse. Therefore, the ablation speed was calculated by an Arrhenius equation while the temperature distribution was simulated by means of the heat conduction equation, which is solvable by a finite differences scheme. Hence, an adaptive mesh is used and the expansion of the code to three spatial dimensions enables the simulation of more complex ablation geometries. The simulation time was held low by introducing actualization frequencies, where critical and time consuming steps were only run if necessary. A validation of the numerical simulation was done by comparing the calculated temperature depth distribution and hole geometry with micrographs of experimental ablations.

Electrocaloric Response in Substrate-Free PMN-0.30PT Thick Films

Recent findings of a large electrocaloric (EC) effect in in polymeric and inorganic ferroelectric materials made this effect an attractive possibility in development of cooling or heating devices of new generation, which would be more environmentally friendly. We report a significant electrocaloric effect near the ferroelectric phase transition in substrate-free [Pb(Mg1/3Nb2/3)O3]1-x[PbTiO3]x (PMN-xPT) with x = 0.30 thick ceramic films on a platinum layer. A method and analysis of direct measurements of the large EC effect are presented. Results confirm that besides the large electrostrictive response already reported in similar self-standing films, the large EC effect of similar magnitude as found in bulk PMN-0.30PT ceramics exists in substrate-free thick films.