Revealing the effects of aerosol deposition on the substrate‐film interface using NaCl coating

Khansur, Neamul H.; Eckstein, Udo; Li, Yizhe; Hall, David A.; Kaschta, Joachim; Webber, Kyle G.

doi:10.1111/jace.16489

Cited by 10 publications

(20 citation statements)

References 43 publications

(118 reference statements)

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“…[ 67 ] New studies by Khansur et al suppose that a change in surface chemistry and polarity as well as a physical interaction of the impacting particles with the substrate material promote a good interface and anchoring layer. [ 68 ] Naoe et al found evidence of the formation of covalent bonds in the interface between a copper substrate and alumina particles. [ 69 ] It is furthermore expected, that the formation of the anchoring layer can be viewed independently from the processes occurring during RTIC including film build‐up and densification through particle–particle interactions during impact.…”

Section: Powder Aerosol Depositionmentioning

confidence: 99%

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

et al. 2020

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Powder aerosol deposition (PAD) is a unique ceramic spray coating method that produces dense and well‐adhering thick‐films directly at room temperature, without requiring any heating or sintering. After the successful film formation, mechanical film properties like hardness or plasma resistance are remarkably good. However, when it comes to electrical properties like permittivity or electrical conductivity, the nanocrystalline structure of PAD films combined with high internal strains deteriorates partly the characteristic properties. The electrical conductivity may already be present within the as‐deposited films. However, it is mostly lowered by several orders of magnitude. Therefore, a thermal post‐deposition annealing is oftentimes required. In this work, electrically conducting films produced by powder aerosol deposition are surveyed based on published data. Their microstructural and electrical behavior during the post‐deposition annealing treatment is summarized and reasons for the lowered electrical conductivity are identified. Additionally, the processes taking place during annealing, which eventually allow to regain bulk‐like functional properties, are examined. A universal annealing behavior is found that leads to a quantitative recommendation for the suitable film annealing temperatures to regain the electrical conductivities.

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Section: Powder Aerosol Depositionmentioning

confidence: 99%

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

et al. 2020

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“…PAD is based on an abrasion and deformation of the substrate surface, as it was observed by various groups, mostly described as a formation of an anchoring layer. [49][50][51] The same may happen to the annealed surface of the first film when depositing the second film. When also the second film is annealed by the laser, the resistance decreases further as shown in Figure 11c,d.…”

Section: Multilayer Pad Film With Multiple Laser-annealing Stepsmentioning

confidence: 99%

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Nazarenus

Kita

Moos

et al. 2020

Adv Materials Inter

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of thermal to electrical energy and vice versa. The state-of-the-art material for thermoelectric generators (TEG) is bismuth telluride (Bi 2 Te 3); however, its application is limited due to its high costs and tendency to oxidize at elevated temperatures. Copper-iron-oxides are a thermally stable promising alternative due to the low costs of the raw materials, their high Seebeck coefficient, and their high electrical conductivity. The PAD method enables to form dense nanocrystalline ceramic films on a variety of substrates with high deposition rates. [16-18] In contrast to all other ceramic processing routes, even moisture-sensitive ceramics, or ceramics with high sintering temperatures can be fabricated at room temperature (RT). [11] Besides the dry ceramic powder, neither additional binders nor other liquids are needed. The ceramic particles are accelerated towards a substrate by a pressure difference. The kinetic energy of the particles is converted into bonding energy during their impact on the substrate and comes along with the reduction of the crystallite size and formation of microstrain within the atomic lattice. [19-21] Particle fracturing occurs along the grain boundaries and within the grains generating temporarily unsaturated surface bonds that cause an excellent adherence of the particles. [22] Despite all the positive aspects of the powder aerosol deposition summarized in Figure 1, a major disadvantage in the as-deposited state that all PAD films have in common is the reduced electrical conductivity of the films. A thermal annealing step is necessary to reduce the mechanical stress of the film and to restore the electrical properties so that they reach bulk values. Exner et al. recently found out that the required annealing temperature in the furnace depends on the melting point of the functional ceramic materials, though it is significantly lower than the typical sintering temperatures. [23] In contrast, laser-based annealing could provide additional advantages like a reduced annealing time or a targeted local property change as it was shown by Palneedi et al. for PZT (Pb(Zr,Ti)O 3) [24-30] and Shinonaga et al. for TiO 2. [31-33] In this study, we investigated the influence of laser irradiation on the properties of a nanocrystalline thermoelectric film. Tin doped copper-iron-oxide respectively copper delafossite (CuFe 0.98 Sn 0.02 O 2), which is known for its good thermoelectric properties and is processability by PAD, [15,34] was synthesized by the mixed-oxide-route. Films were fabricated by powder aerosol deposition method. After deposition, the films were annealed with a frequency tripled Nd:YAG laser (λ = 355 nm) and its influence on the microstructure and the electrical properties was examined by optical and electrical measurements. Powder aerosol deposition (PAD) is a unique coating method that allows the fabrication of dense ceramic films on a variety of substrates at room temperature. This spraying process can produce film thicknesses of several micrometers within minutes without the use of...

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“…According to the polarization switching model by Hwang et al., [ 99 ] a certain threshold energy ( w ds ) is required to reorient domains, and it can be expressed in terms of the electric field and mechanical stress components:

\begin{matrix} σ_{i j} Δ ε_{i j} + E_{i} Δ P_{i} \geq w_{ds} \end{matrix}

where σ ij and E i are the applied stress and electric field and ∆ ε ij and ∆ P i change in strain and polarization during a ferroelectric or ferroelastic switch. In the present case, the biaxial residual stress in the substrate [ 65,68 ] is acting cooperatively with the electric field applied perpendicular to the film/substrate interface, thereby reducing the electrical energy required to induce a long‐range ferroelectric order and reorient domains. This additional mechanical energy, however, is not present in the sample with the sputtered electrode, resulting in a higher applied electric field required.…”

Section: Resultsmentioning

confidence: 99%

“…[ 65 ] Moreover, during the initial layer formation in the AD process, the deposition stresses need to be accommodated by the substrate, that is, plastic deformation and internal residual stress are also induced in the substrate. [ 68 ] This effect, for example, has been shown to result in plastic deformation of Si substrates during AD. [ 69 ]…”

Section: Introductionmentioning

confidence: 99%

Enhanced Electromechanical Response and Thermal Stability of 0.93(Na_1/2Bi_1/2)TiO₃‐0.07BaTiO₃ Through Aerosol Deposition of Base Metal Electrodes

Khansur

Eckstein

Sadl

et al. 2021

Adv Materials Inter

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Na1/2Bi1/2TiO3‐based relaxor ferroelectrics are extensively investigated for use in transduction applications because of their relatively large electromechanical properties. Integration of these materials into devices, however, requires better temperature stability in addition to electromechanical properties. This work demonstrates a novel approach to enhance the temperature stability of the long‐range ferroelectric order as well as to enhance electromechanical properties in a non‐ergodic relaxor 0.93(Na1/2Bi1/2)TiO3‐0.07BaTiO3 (NBT‐7BT) without changing the chemical composition through, for example, chemical substitutions or second phase particles. The approach involves the room temperature deposition of copper electrodes directly on the relaxor ceramic substrate using the aerosol deposition (AD) method. The collision of solid‐state particles with the substrate surface during AD results in large impact and residual stresses, inherent to the AD process, which are shown with piezo‐response force microscopy to induce long‐range ferroelectric domain ordering in non‐ergodic relaxor NBT‐7BT. Using Raman spectroscopy, the magnitude and depth profile of the stress‐induced transformation are determined. It is demonstrated that deposition‐induced stresses significantly increase the temperature stability of the electromechanical properties, where long‐range ferroelectric ordering is observed up to 150 °C, which is approximately 41 °C higher than NBT‐7BT samples without the AD processed electrode. Moreover, the AD treatment also facilitates ferroelectric domain switching at a lower electric field, enabling maximum polarization at a relatively lower field and an enhancement in the piezoelectric response. It is shown that the deposition‐induced stress is responsible for such an enhancement. Importantly, this impact‐stress‐driven tailoring of electromechanical properties can potentially be utilized for other functional ceramic materials as well, where internal residual stress can result in enhanced functional properties.

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Revealing the effects of aerosol deposition on the substrate‐film interface using NaCl coating

Cited by 10 publications

References 43 publications

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Enhanced Electromechanical Response and Thermal Stability of 0.93(Na_1/2Bi_1/2)TiO₃‐0.07BaTiO₃ Through Aerosol Deposition of Base Metal Electrodes

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Revealing the effects of aerosol deposition on the substrate‐film interface using NaCl coating

Cited by 10 publications

References 43 publications

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

What Happens during Thermal Post‐Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment‐Enhanced Literature Survey

Laser‐Annealing of Thermoelectric CuFe0.98Sn0.02O2 Films Produced by Powder Aerosol Deposition Method

Enhanced Electromechanical Response and Thermal Stability of 0.93(Na1/2Bi1/2)TiO3‐0.07BaTiO3 Through Aerosol Deposition of Base Metal Electrodes

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Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Enhanced Electromechanical Response and Thermal Stability of 0.93(Na_1/2Bi_1/2)TiO₃‐0.07BaTiO₃ Through Aerosol Deposition of Base Metal Electrodes