A diffusion model for the oxidation of hot pressed Si3N4-Y2O3-SiO2 materials

Babini, G.N.; Bellosi, A.; Vincenzini, P.

doi:10.1007/bf00540473

Cited by 53 publications

(18 citation statements)

References 9 publications

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“…The link is that the products of the "secondary" system form as a consequence of reactant species emerging from the "primary" system. Previous studies show that material transfer from the "primary" to the "secondary" system causes a continuous compositional change in the intergranular phase with formation of a gradient of depleted additive and impurity cations in the material [2,8,9].…”

Section: Discussionmentioning

confidence: 99%

“…Parabolic weight gain curves were always observed. A detailed discussion of the kinetics and thermodynamics of the oxidation process is reported elsewhere [2]. aluminium, iron etc.)…”

Section: Methodsmentioning

confidence: 99%

“…The cristobalite content in the oxide always decreases with oxidation temperature up to TABLE III Final compositions calculated according to Babini et al [2] for the hot-pressed materials from the Si3N,-Y203-SiO 2 system obtained from batches in Table I. 1Y2 2Y2 3Y2 4Y2 1Y3 2Y3 3Y3 4Y3 1Y5 2Y5 3Y5 …”

Section: Structure Of the Oxidementioning

confidence: 99%

“…1 description of the grain-boundary phase on the basis of the ternary Si3N4-Y203-SiQ diagram. Nevertheless, by assuming specific reactions between Si3N4, Y203, SiO2 and impurities [ 1,2], the composition of the grain-boundary phase of the hot-pressed samples reported in Table III is obtained which has been shown [2] to represent adequately the real material, at least in terms of relative volumes of each constituent, in spite of the fact that the specific compounds used in the description are not exactly the same as those detected in the grain-boundary phase by X-ray diffraction.…”

Section: Phase Composition Of the Hot-pressed Materialsmentioning

confidence: 99%

“…A diffusional model for the oxidation of Si3N4-Y203-Si02 hot-pressed materials, which is also useful for other dense nitrogen ceramics, has been developed previously [1,2]; it proves useful in discussing both kinetic (oxidation rate constants K) and thermodynamic (apparent activation energy) aspects of the process. The amount of grain-boundary phase and concentration gradients of additive and metal impurities between the unreacted material and the silicon nitride/oxide reaction interface are the main parameters of the material introduced in the model.…”

Section: Introductionmentioning

confidence: 99%

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Factors influencing structural evolution in the oxide of hot-pressed Si3N4-Y2O3-SiO2 materials

1984

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X-ray diffraction, SEM, EDS and WDS studies were performed of the structure and morphology of the oxide developed on hot-pressed compositions of the Si3N4-Si2N20-Y2Si207 sub-system subjected to short-term ('~ 30 h) oxidation in air at T = 1273 to 1673 K. Viscosity of the oxide glassy phase, ionic mobility and oversaturation degree of the atomic species involved were found to be the most important parameters in the control of structural evolution of the oxide. Clear links appear to exist between compositional parameters of the grain-boundary phase of the hot-pressed materials and the evolution of the crystal phases in the oxide. The 2;Mi/Y ratio (I;Mi, total amount of metal impurities) in the grain-boundary phase, seems to play a major role in the transport properties of the oxide glassy phase.

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Section: Discussionmentioning

confidence: 99%

“…Parabolic weight gain curves were always observed. A detailed discussion of the kinetics and thermodynamics of the oxidation process is reported elsewhere [2]. aluminium, iron etc.)…”

Section: Methodsmentioning

confidence: 99%

Section: Structure Of the Oxidementioning

confidence: 99%

Section: Phase Composition Of the Hot-pressed Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Factors influencing structural evolution in the oxide of hot-pressed Si3N4-Y2O3-SiO2 materials

1984

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Magneto‐optical garnets for integrated optoelectronic devices

Wehlus

Körner

Leitenmeier

et al. 2010

Physica Status Solidi (a)

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One of the efforts of integrated optics is the integration of macroscopic optical components such as an optical isolator on a single chip. Therefore magneto‐optically active materials with high Faraday rotations are needed. Bismuth iron garnet (BIG) Bi3Fe5O12 is known for its high Faraday rotation at room temperature, but it forms in a non‐thermodynamic way and only grows on garnet substrates like gadolinium gallium garnet (GGG) Gd3Ga5O12. Our ambition was to investigate the possibility of depositing such an integrated optical device based on magneto‐optical BIG. A general overview of our extensive fundamental research is given in this paper. We first analysed the growth mechanisms of BIG on GGG, especially the nucleation process and the film growth which are important for BIG film synthesis. Then we worked on a garnet buffer system to enable film formation on other substrate materials like silicon or fused silica. To obtain the optical constants of the deposited material, a fitting algorithm was implemented. It calculates the optical properties of material stacks from transmission measurements. Furthermore, we wanted to vary the lattice constants of the garnets for a better adaption to the substrates. Because different rare earth elements have different atomic radii, it should be possible to vary the lattice constant by incorporating these atoms in the crystal. Therefore a number of rare earth doped garnets were produced and their film properties were analysed. During the buffer development we found an oscillatory effect in the Faraday rotation, which was examined in detail.

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Oxidation in Oxygen and Air

Gogotsi

Lavrenko

1992

Corrosion of High-Performance Ceramics

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A diffusion model for the oxidation of hot pressed Si3N4-Y2O3-SiO2 materials

Cited by 53 publications

References 9 publications

Factors influencing structural evolution in the oxide of hot-pressed Si3N4-Y2O3-SiO2 materials

Factors influencing structural evolution in the oxide of hot-pressed Si3N4-Y2O3-SiO2 materials

Magneto‐optical garnets for integrated optoelectronic devices

Oxidation in Oxygen and Air

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