Formation of β‐Silicon Nitride Crystals from (Si,Al,Mg,Y)(O,N) Liquid: I, Phase, Composition, and Shape Evolutions

Wang, Lingling; Tien, Tseng‐Ying; Chen, I‐Wei

doi:10.1111/j.1151-2916.2003.tb03517.x

Cited by 28 publications

(8 citation statements)

References 21 publications

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“…On the basis of the interfacial segregation mechanism of cations, Wang et al [91] proposed an acid-based model to explain the effects of the liquid-phase composition on the anisotropic grain growth of β-Si 3 N 4 . In this model, silicon and aluminum are a strong acid and weak acid, respectively, and the basicity of yttrium and RE bases increases as the ionic size increases.…”

Section: Acid-base Modelmentioning

confidence: 99%

Textured silicon nitride: processing and anisotropic properties

Zhu

Sakka

2008

Science and Technology of Advanced Materials

158

104

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Textured silicon nitride (Si 3 N 4 ) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si 3 N 4 , with emphasis on the anisotropic and abnormal grain growth of β-Si 3 N 4 , texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si 3 N 4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si 3 N 4 single crystals are presented. Various anisotropic properties of textured Si 3 N 4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si 3 N 4 with a unique microstructure composed of oriented elongated β-Si 3 N 4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured α-Sialon using the same methods as those used for textured β-Si 3 N 4 and β-Sialon.

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Section: Acid-base Modelmentioning

confidence: 99%

Textured silicon nitride: processing and anisotropic properties

Zhu

Sakka

2008

Science and Technology of Advanced Materials

158

104

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“…in Ref. ), which is well‐ known as a general phenomenon in the crystal/grain growth of various materials, such as α‐Sialon, β‐Sialon, Si 3 N 4 , zeolite . The growth of those crystals/grains mostly occurs in the stage of Oswald ripening with a remarkable feature of coarsening kinetics: larger crystals/grains grow at the expense of smaller ones.…”

Section: Resultsmentioning

confidence: 98%

Effect of Y‐α‐Sialon Seeding and Holding Time on the Formation of Elongated (Ca,Dy)‐α‐Sialon Crystals Prepared via Carbothermal Reduction and Nitridation

et al. 2012

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Single‐phase (Ca,Dy)‐α‐Sialon with elongated crystals and high aspect ratios was prepared at 1700°C by carbothermal reduction and nitridation (CRN) with Y‐α‐Sialon seed crystals. Effects of Y‐α‐Sialon seeding and holding time on the phase assemblage and crystal morphology of CRN products were discussed. The results showed that adding seed crystals and prolonging holding time could facilitate not only phase transformation, but also crystal refinement. Moreover, they resulted in the increase of the aspect ratios of α‐Sialon crystals, due to the decreasing range in the crystal width exceeding that in the length. In addition, a highly unusual phenomenon of crystal size reduction during reaction was observed in the seeded samples with the holding time extending from 2 to 4 h. Crystallization from liquid phase and growth followed by nucleation based on the surface of existing large crystals were the growth modes of elongated α‐Sialon crystals.

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“…Intergrowth of aand b-structures has only been observed in the heterogeneous nucleation of b-phase onto the a-nuclei probably because only supersaturation could overcome the large lattice mismatch between the two phases. 26,27 Previous firstprinciples molecular-orbital calculations suggested that the Si(Al)-N(O) bonds are strengthened by the presence of a trivalent positive charge at the interstitial site of the a-Sialon crystal. 28 The present observation further indicates that the Ce 3þ ions can stabilize the a-Sialon structure in a strain field.…”

Section: (B) Resultsmentioning

confidence: 99%

Atomic-scaled investigation of structure-dependent luminescence in Sialon:Ce phosphors

Sourty¹

2012

Applied Physics Letters

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Here, we present direct correlation of luminescence properties to the atomic structures of Sialon:Ce phosphors. Luminescence of β-Sialon is revealed attributed to the intergrowth of a unit layer of α-Sialon:Ce-type structure on β-grain surfaces. The dense doping at fault sites either on the surface of or inside the α-Sialon crystallites might lead to intensified emission of light depending on the fault morphology. It seems that concentration quenching would not appear for Sialon:Ce phosphors unless high density of dislocations is created upon dense doping. Finally, structural evolution has been discussed aiming to greatly enhance the luminescence of Sialon phosphors.

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Formation of β‐Silicon Nitride Crystals from (Si,Al,Mg,Y)(O,N) Liquid: I, Phase, Composition, and Shape Evolutions

Cited by 28 publications

References 21 publications

Textured silicon nitride: processing and anisotropic properties

Textured silicon nitride: processing and anisotropic properties

Effect of Y‐α‐Sialon Seeding and Holding Time on the Formation of Elongated (Ca,Dy)‐α‐Sialon Crystals Prepared via Carbothermal Reduction and Nitridation

Atomic-scaled investigation of structure-dependent luminescence in Sialon:Ce phosphors

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