Nitrogen-rich liquid phase regions in the LnSiAlON (Ln = Nd, Sm, Gd, Dy, Er and Yb) systems

Sun, Weiying; Tu, Heng; Wang, P.L.; Yan, Dongsheng

doi:10.1016/s0955-2219(96)00123-9

Cited by 15 publications

(8 citation statements)

References 8 publications

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“…The interfacial bond strength, which governs the debonding behavior of the interfaces between oxynitride glasses and Si 3 N 4 grains, increases with increasing Al and O contents in the epitaxial sialon layers formed on the grains. 16,18 Sun et al 19 investigated the nitrogen-rich liquid phase region in the lanthanide Ln-Si-Al-O-N systems and found that the glass-forming regions at 40 eq% N were relatively extensive and contracted towards silicon-rich compositions with increasing nitrogen content. 10 The specific properties of Ca a-sialon ceramics: a large solubility of Ca 21 in the a-sialon structure, 11-13 a high thermal stability, 14 and the feasibility 6,15 to obtain whisker like microstructures makes the Ca-a-sialon system worthy of extensive investigations.…”

Section: Introductionmentioning

confidence: 99%

Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Cai

Shen

Grîns

et al. 2008

Journal of the American Ceramic Society

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In developing elongated α‐sialon grains, a nitrogen‐rich liquid phase sintering method was introduced by using CaH2 as a sintering aid, so as to vary the N/O ratio of the liquid phase formed in the sintering process while keeping the Si/Al ratios constant. With increasing addition the phase contents changed from single β‐sialon to dual β/α‐sialons and to single Ca‐α‐sialon. At low N/O ratios the microstructures contained mainly equiaxed β‐sialon grains, and at high N/O ratios well faceted elongated Ca‐α‐sialon grains. The improved toughness (KIC=7.8 MPa·m1/2) and hardness (HV10=17.5 GPa) properties can be attributed to the formation of interlocked microstructures. High‐temperature compressive deformation tests indicated that the deformation onset temperature is determined mainly by the Si/Al and N/O ratios, whereas the deformation rate is affected by the microstructure, i.e., the morphology and amounts of elongated α‐sialon grains and residual glass phase, especially for the sialons with low N/O ratios.

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Section: Introductionmentioning

confidence: 99%

Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Cai

Shen

Grîns

et al. 2008

Journal of the American Ceramic Society

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“…These compositions were based on earlier phase equilibrium studies conducted on various Si-Al-RE-O-N systems. 14,15 The rare earths included La, Nd, Gd, Y, and Lu, which, with the possible exception of Nd, only exhibit a valence of 3ϩ. This choice was made to eliminate any ambiguities that might result from concerns with the actual valence of the RE ions in the glass (e.g., Ref.…”

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confidence: 99%

Compositional Effects on the Properties of Si‐Al‐RE‐Based Oxynitride Glasses (RE = La, Nd, Gd, Y, or Lu)

Becher

Waters

Westmoreland

et al. 2002

Journal of the American Ceramic Society

116

114

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A series of silicon-aluminum oxynitride-glass compositions containing selected rare-earth (RE) additions were prepared to examine the effects of specific RE, as well as Si:Al:RE and N:O ratio, on properties. The properties that were characterized included density, thermal expansion coefficient (␣), glasstransition temperature (T g ), hardness (H), and Young's modulus (E). The compositions (in equivalent percent) selected included: 55 Si-20 RE-25 Al oxide and 80 O-20 N oxynitride, and 45 Si-30 RE-25 Al oxide and 70 O-30 N glasses. The results show that the density increased significantly with an increase in the RE atomic mass and slightly with an increase in N:O ratio. For each of the fixed Si-Al-RE-O-N compositions, the E, H, and T g values were each increased by substituting smaller RE ions, whereas the ␣ value was decreased. For each specific cation composition and RE, increasing the N:O ratio systematically led to a decrease in the ␣ values but an increase in the E, H, and T g values. The observed response in the glass properties to changes in composition appears to reflect modifications in the bonding within the glass network. I. BackgroundT HE manner in which the composition of oxynitride glasses influences their properties is of considerable interest for at least two reasons. First, such glasses exhibit various properties that could be of interest for numerous applications. For example, the Si-Al-Y-O-N glasses (1) are very refractory, with a glass-transition temperature (T g ) Ͼ900°C, (2) have E values higher than those of oxide glasses, and (3) exhibit a range of ␣ values. 1-5 Indeed, the properties apparently can be readily modified by tailoring the compositions. Studies 6 -10 have shown that the substitution of lanthanide-series ions for yttrium can be used to modify elastic and thermal properties, as well as glass viscosity. Shelby and Kohli 11 observed an increase in ␣ values and a decrease in T g values as the rare-earth (RE) ion size increased in 50 Si-25 RE-25 Al oxide glasses. Ohashi et al. 9 found that both the E and T g values increased with increases in the RE cationic field strength (valence/ (r 3ϩ ) 2 , where r 3ϩ is the radius of RE 3ϩ in sixfold coordination) in oxynitride glasses with a composition of 64 Si-36 RE-20 N-80 O. In 56 Si-28 RE-16 Al-17 N-83 O glasses, Ramesh et al. 10 observed a decrease in ␣ and an increase in H and T g with an increase in cationic field strength of the RE. Increases in T g with decreases in the RE ionic radius were found in both 51 Si-11 RE-38 Al-23 N-77 O and 40 Si-23 RE-37 Al-100 O glasses, and E increased with RE size in the latter glass. 7,8 In addition, the oxidation resistance of the Si-Al-RE-O-N glasses increased with decreases in the radius of the RE ion. 8 Finally, the refractive index (n) and magneto-optical properties of 50 Si-25 RE-25 Al oxide glasses were functions of the specific RE ion size (e.g., n ϰ 1/r 3ϩ ) and content. 11,12 Currently, considerable effort is underway to improve silicon devices by developing thin (Ͻ3 nm) film gate oxide films...

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“…14,15 The amount and composition of the liquid phase have to be considered in order to achieve a suitable viscosity, so that material transport can be efficient and, consequently, high densification can occur. [16][17][18] Because most rare-earth additives do not form a solid solution with SiC, the liquid phase after cooling is located at grain boundaries as an amorphous or partially crystalline phase. In other words, the SiC grains are surrounded by an intergranular glass or an intergranular film containing the rare-earth element, according to a similar mechanism found in typical silicon nitride sintering process.…”

Section: Sintering Of Silicon Carbide (Sic) Ceramicsmentioning

confidence: 99%

Mixture Design and Response Surface Analysis of Densification of Silicon Carbide Ceramics with (SiO₂–Dy₂O₃–Al₂O₃) Additives

Marchi

Bressiani

et al. 2010

Int J Applied Ceramic Tech

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Statistical mixture designs are used to systematically study the densification properties of silicon carbide (SiC) ceramics sintered with SiO 2 , Dy 2 O 3 , and Al 2 O 3 . Mixture models for percentage theoretical density and SiC weight loss as a function of the SiO 2 , Dy 2 O 3 , and Al 2 O 3 oxide proportions have been determined and validated by analysis of variance. The results indicate a region confined by about 0-20 mol% silica, 50-65 mol% dysprosia, and 40-65 mol% alumina, with all samples containing 10% by volume of additives, and simultaneously maximization of density values and minimization of weight loss during SiC-based ceramic sintering.

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Nitrogen-rich liquid phase regions in the LnSiAlON (Ln = Nd, Sm, Gd, Dy, Er and Yb) systems

Cited by 15 publications

References 8 publications

Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Compositional Effects on the Properties of Si‐Al‐RE‐Based Oxynitride Glasses (RE = La, Nd, Gd, Y, or Lu)

Mixture Design and Response Surface Analysis of Densification of Silicon Carbide Ceramics with (SiO₂–Dy₂O₃–Al₂O₃) Additives

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Nitrogen-rich liquid phase regions in the LnSiAlON (Ln = Nd, Sm, Gd, Dy, Er and Yb) systems

Cited by 15 publications

References 8 publications

Sialon Ceramics Prepared by Using CaH2 as a Sintering Additive

Sialon Ceramics Prepared by Using CaH2 as a Sintering Additive

Compositional Effects on the Properties of Si‐Al‐RE‐Based Oxynitride Glasses (RE = La, Nd, Gd, Y, or Lu)

Mixture Design and Response Surface Analysis of Densification of Silicon Carbide Ceramics with (SiO2–Dy2O3–Al2O3) Additives

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Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Sialon Ceramics Prepared by Using CaH₂ as a Sintering Additive

Mixture Design and Response Surface Analysis of Densification of Silicon Carbide Ceramics with (SiO₂–Dy₂O₃–Al₂O₃) Additives