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

Exner, Jörg; Nazarenus, Tobias; Hanft, Dominik; Kita, Jarosław; Moos, Ralf

doi:10.1002/adma.201908104

Cited by 39 publications

(39 citation statements)

References 154 publications

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“…The results are in contrast to findings in literature, according to which furnace‐annealing with moderate heating and cooling rates as well as long dwell times leads to a reduction of the reflex widths and hence to grain growth at higher temperatures. [ 3,10,11,23,41 ] The observed phenomenon can be explained by high heating and cooling rates caused by the laser that may lead to a glassy microstructure. However, a glassy microstructure cannot be detected by XRD analysis.…”

Section: Resultsmentioning

confidence: 99%

“…One reason for the increase of the conductivity is the reduction of strain within the film. [23] On the one hand, the conductivity of the PAD surface layer after laser-annealing is still reduced compared to the www.advmatinterfaces.de conductivity of bulk samples in literature (σ bulk = 0.06 to 0.09 S cm −1 ). [15] On the other hand, the conductivity of the surface layer is close to a CuFeO 2 PAD film that was annealed in a furnace at 900 °C (σ CuFeO2, ref = 0.03 S cm −1 ) and sol-gel dipcoated films after an annealing at 800 °C for at least 1 h. [15,48] When the microstructure of the surface layer is taken into account, the microcracks might lower the conductivity.…”

Section: Wwwadvmatinterfacesdementioning

confidence: 97%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Wwwadvmatinterfacesdementioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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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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“…Vickers' microhardness test con rms that the hardness of lms was about 2.4 times higher than the sintered bulk samples. Film crystallites size was about 9 times lower than that of the mixed powder, and nally, the XRD, SEM, and hardness test results con rm that the PAD lm is suitable for electrical studied [105,[107][108][109][110][111][112]. At lower temperature (400 °C) lm sample showed a lower conductivity of 2.5 x 10 −8 S/cm, which is 3.5 order lower than the bulk one.…”

Section: Composites and Thin Lmsmentioning

confidence: 75%

Recent progress in the experimental and theoretical studies on the barium zirconate proton conductors: A review

Hossain¹,

Biswas²,

Chanda³

et al. 2021

Preprint

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There have been significant developments of solid-state-ion conducting energy materials and perovskite-based oxides those exhibit excellent proton conduction at intermediate temperatures. In contrast to high-temperature oxygen ion-conducting oxides or low-temperature proton-conducting polymers, perovskite oxides have obtained distinguished attention because of their diversified structural aspects and potential applications. Highly stable and conductive electrolytes with improved electrochemical and thermochemical properties are in great demand in numerous fields such as portable electronics and transport systems, energy storage, fuel cells, etc. This review focuses on recent development in the proton-conducting performance of BaZrO 3 (BZO) energy materials. This study aims to integrate the fundamentals of proton conducting BZO perovskites in the prospect of the recent development in materials science and computational engineering. Therefore, in the first half of this review, the basic overview of the BZO perovskites structure, fundamentals of working principles, fabrication, and processing methods underlying the successful development of these materials with superior performance is discussed. The second part principally concentrates on the significant improvement towards higher conductive BZO perovskite fabrication with the help of theoretical studies via density functional theory (DFT) based first-principles calculation and molecular dynamics (MD) simulation followed by the prominent applications in low-temperature solid oxide fuel cells. The presented information on in-depth analysis of the physical properties of barium zirconate from experimental and theoretical studies will guide aspirants in further conducting research in this field near future.

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“…Properties such as crystallite size, microstrain, and conductivities of coatings prepared from certain materials with PAD can be modified by thermal post-treatment [ 11 ], which can have a positive influence on their usability. However, there are various aspects thought to be influencing the deposition, like the powder pre-treatment [ 12 ] or aerosol generation [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Powder Aerosol Deposition Method Using Shadowgraph Imaging

et al. 2021

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The powder aerosol deposition method (PAD) is a vacuum-based spray coating technology. It allows for production of highly dense coatings at room temperature, especially of brittle-breaking materials. This yields new options for coating substrate materials that even melt at low temperatures. The film formation mechanism is called room temperature impact consolidation (RTIC). The occurrence of this mechanism is strongly linked to the gas jet used in the process. The velocity and direction of the particles in the gas jet forming between the nozzle orifice and the substrate are the main factors influencing the quality of the coating. This dependency aimed to be elaborated with a measurement setup and coating experiments and is shown in this work. We investigated the gas jet formation using a shadow optical imaging system. Regions of different gas density are visualized by this technique. Several parameter sets, in particular gas flow rates and chamber pressures, were investigated. In addition, coatings were produced on glass substrates with the same parameters. As a coating material, the superconducting ceramic-like magnesium diboride (MgB2) was chosen. A correlation between shadow images and thickness profiles of the coatings shows how the gas jet formation affects the uniformity of thickness. Shadow optical images provide valuable information on the flight direction of the particles and allow validation of simulation results.

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

Cited by 39 publications

References 154 publications

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

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

Recent progress in the experimental and theoretical studies on the barium zirconate proton conductors: A review

Investigation of the Powder Aerosol Deposition Method Using Shadowgraph Imaging

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

Cited by 39 publications

References 154 publications

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

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

Recent progress in the experimental and theoretical studies on the barium zirconate proton conductors: A review

Investigation of the Powder Aerosol Deposition Method Using Shadowgraph Imaging

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

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