Evolution of aluminosilicate structure and mullite crystallization from homogeneous nanoparticulate sol–gel precursor with organic additives

Leivo, Jarkko; Lindén, Mika; Rosenholm, Jessica M.; Ritola, Merja; Teixeira, Cilâine Verônica; Levänen, Erkki; Mäntylä, T.

doi:10.1016/j.jeurceramsoc.2007.12.033

Cited by 48 publications

(16 citation statements)

References 69 publications

(117 reference statements)

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“…XRD analyses of the mullite-coated Al 2 O 3 inverse opals (photonic crystals) presented peaks related to the mullite phase when heat treated at 1100 °C for 1 h (Figure 7) Mullite conversion temperature according to the mixing homogeneity scale, related to the processing route a) monophasic sol-gels (type I), [28,[57][58][59] (a′) monophasic nanoparticulate sol-gel, [60] b) CVD, [30,35] c) EB-PVD with layer thickness ≈2 nm, [36] (c′) EB-PVD with layer thickness ≈9 nm, [36] d) diphasic sol-gel (type II), [28,41,42,61] e) powder metallurgy + sol-gel (coated powders), [28,62,63] and f) powder metallurgy. [43] The symbol ♦ indicates atomic layer deposition (result from this study).…”

Section: Photonic Crystal Stabilitymentioning

confidence: 99%

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Furlan

Krekeler

Ritter

et al. 2017

Adv Materials Inter

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coatings on geometrically complex substrates, [2][3][4] such as anodic aluminum oxide membranes, aerogels, photonic crystals, and nanorods, with a film thickness control on the Å-scale. Additionally, by combining two or more binary ALD processes in a super cycle ALD process, multicomponent materials can be achieved, such as nanolaminates, doped thin films, and ternary or quaternary oxides. [5] The ability of compositional control of thin films at an atomic level provides the possibility for development of tailor-made atomically mixed systems, pointing to novel materials functionalities.Direct and inverse opals are examples of photonic crystals, which can be manufactured by colloidal self-assembly [6,7] and ALD. [8,9] Its high ordered porosity of interconnects is attractive for a variety of technological applications, such as porous membranes, catalysts, solid oxide fuel cells, and photonics applications. [10][11][12] The 3D periodic arrangement of pores provides a photonic bandgap to these artificial materials, which prohibits the transmission and hence leads to a reflection of electromagnetic radiation in spectral range which is determined by the materials' properties. Specifically, the radiation wavelength, which will be reflected, is influenced by the material microstructure assemble, mono-or multistacked, and also the macropore size. [8,9,[13][14][15] This selective behavior in transmission and reflection might pave the way to effective solar thermo photovoltaic energy conversion devices [16,17] and also next-generation thermal barrier coatings.However, retention of the 3D structure for high-temperature applications remains a significant challenge. [10,18] As the length scales in these porous materials are decreased, as higher is the surface area and specific activity. When exposed to high temperatures, the material's structure may suffer from detrimental morphological changes, such as extensive grain growth, distortion, and eventually destruction of the total periodically organized structure. [9,10] Therefore, this material needs to not only interact with electromagnetic radiation but also have structural stability and keep its function up to high temperatures (usually higher than 1000 °C). The latter fact could be addressed by coating the substrate material with a ceramic oxide that is stable at high temperatures, either by chemical vapor deposition (CVD) [19] or ALD [20] processes.Herein, mullite has been chosen: A ceramic material, which is well known for its stability at high-temperature environments, Atomic layer deposition (ALD) process presents thickness control in an Ång-strom scale due to its inherent surface self-limited reactions. In this work, an ALD super cycle approach, where a superposition of nanolaminates of SiO 2 and Al 2 O 3 is generated by cycling the precursors APTES-H 2 O-O 3 and TMA-H 2 O, is used to deposit thin films with varying ratio of Al 2 O 3 :SiO 2 into silicon wafers and into inverse photonic crystals. The resulting ternary oxide films deposited at low temperature (150 °C) ar...

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Section: Photonic Crystal Stabilitymentioning

confidence: 99%

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Furlan

Krekeler

Ritter

et al. 2017

Adv Materials Inter

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“…The main phases in the as-prepared coating are mullite and cristobalite. These form when the monophasic mullite precursors crystallize into an Al 2 O 3 -rich pseudo-tetragonal mullite at about 1253 K. Then the Al 2 O 3 -rich mullite gradually transforms into 3:2 orthorhombic mullite by reaction with the silica phase upon being further heated above 1573 K. The latter transformation step is slow because the diffusion rate is limited [26][27][28]. In addition, no peak of SiC or Si is found, indicating that a dense mullite outer coating with enough thickness has formed.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and oxidation behavior of sol–gel mullite coating on SiC-coated carbon/carbon composites

Zhou

Xiao

et al. 2015

Journal of the European Ceramic Society

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“…4 shows the XRD analysis results for samples TU-0, TU-1 and TU-3 calcined at 1000°C for 2 h and Fig. 5 shows the infrared spectra for samples AU-0, AU-1 and AU-3, treated at 1250°C for 2 h. The corresponding wave number values and the band assignments are listed in Table 3 [18,19].…”

Section: Resultsmentioning

confidence: 99%

“…Band positions and assignments for the various vibrational modes for samples AU-0, AU-1 and AU-3 treated at 1250°C for 2 h[18,19].…”

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confidence: 99%

Effect of urea on the mullite crystallization

Cividanes

Campos

Bertran

et al. 2010

Journal of Non-Crystalline Solids

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Due to its chemical, physical and mechanical properties, mullite has been used in equipments subjected to extreme mechanical strain and high temperatures. This paper reports the study of the effect of urea on the mullite crystallization, synthesized through the colloidal and polymeric sol-gel processes, using XRD and FT-IR. The colloidal precursors were obtained from silicic acid, water, aluminum nitrate nonahydrate (ANN) and urea. The polymeric precursors were obtained from TEOS, ethanol, ANN and urea. For both methods, urea was used in the molar ratio urea/Al 3+ equal to 0/1, 1/1 and 3/1. The urea addition in colloidal gels led to materials with higher concentrations of orthorhombic mullite, besides they crystallized mullite at lower temperatures (positive effect). However, a negative effect was observed when urea was added to polymeric gels. In addition, the amount of crystallized mullite increased with the urea content in the colloidal gels. The colloidal sample with the highest urea content proved to form mullite at a lower temperature. Moreover, this sample did not segregate the α-alumina phase. The positive effect of urea in the colloidal gels is related to its participation in the hydrolysis and condensation steps of aluminum and silicon, avoiding the extensive phase segregation of silica and alumina. The negative effect observed in the polymeric samples may have occurred due to a competition between the silanol, the ANN and urea by water molecules. The only water molecules that are present in the polymeric gel are those that are part of the ANN.

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Evolution of aluminosilicate structure and mullite crystallization from homogeneous nanoparticulate sol–gel precursor with organic additives

Cited by 48 publications

References 69 publications

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Microstructure and oxidation behavior of sol–gel mullite coating on SiC-coated carbon/carbon composites

Effect of urea on the mullite crystallization

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