Fracture toughness of YBa2Cu3O6+δ single crystals: Anisotropy and twinning effects

Raynes, Alan S.; Freiman, Stephen W.; Gayle, Frank W.; Kaiser, Debra L.

doi:10.1063/1.350234

Cited by 65 publications

(27 citation statements)

References 8 publications

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“…Although high-temperature elastic modulus is not reported, strain energy of YBCO which is simply strained by a mismatched NGO substrate, is estimated using room temperature elastic modulus of YBCO [13,14] Fig. 4(a,b), this relation suggests that c-axis orientation on NGO(110) substrate maintains to be more stable than a-axis orientation at the experimental temperatures, contrary to the experimental observation.…”

Section: Discussioncontrasting

confidence: 53%

Temperature dependence of growth orientation of YBa2Cu3O6+δ film on NdGaO3 using liquid-phase epitaxy

Nasu¹,

Yamada²,

Kubo³

2008

Journal of Crystal Growth

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Section: Discussioncontrasting

confidence: 53%

Temperature dependence of growth orientation of YBa2Cu3O6+δ film on NdGaO3 using liquid-phase epitaxy

Nasu¹,

Yamada²,

Kubo³

2008

Journal of Crystal Growth

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“…The change in crystalline orientation at twin boundaries could account for the multiple deflections of the main crack path. A similar behavior has been reported in single crystals of YBa2Cu306+B, with a 25% increase in fracture toughness for the twinned crystals compared with the untwinned crystals (Raynes et al, 1991). Some of the microscopic features observed suggested crack bridging, with intact islands of material left on the main crack path (Figs.…”

Section: Discussionsupporting

confidence: 64%

Effect of Ion Exchange on the Microstructure, Strength, and Thermal Expansion Behavior of a Leucite-reinforced Porcelain

1998

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Leucite (KAlSi2O6) is used as a reinforcing agent in some porcelains for all-ceramic restorations; however, it increases their coefficients of thermal expansion, imposing constraints on the processing of the material. The potassium ions in leucite are exchangeable for rubidium or cesium ions, leading to rubidium leucite or cesium leucite (pollucite). Both rubidium leucite and pollucite exhibit a lower coefficient of thermal expansion and inversion temperature than leucite. The purpose of this study was to evaluate the effects of rubidium and cesium leucites on thermal expansion, microstructure, crack deflection patterns, and flexural strength of a leucite-reinforced porcelain. A dental porcelain powder was mixed with rubidium or cesium nitrate and heat-treated. Porcelain bars (n = 3) and discs (n = 15) were made with the exchanged powders. X-ray diffraction analyses were performed before and after bars were fired. Controls were made of untreated Optec HSP porcelain powder, formed into bars and disks, and baked following manufacturer's recommendations. The density of all specimens was determined by Archimedes' method. The thermal expansion behavior of the materials was measured by dilatometry. The microstructure and Vickers indentation crack patterns were investigated by scanning electron microscopy. X-ray diffraction showed that after ion-exchange and firing, leucite transformed into either tetragonal rubidium leucite or cubic cesium leucite. The mean coefficient of thermal contraction (550 to 50 degrees C) was significantly (p < 0.003) greater for the control material, followed by the rubidium-exchanged material, and lowest for the cesium-exchanged material. Crack pattern analyses revealed that the cesium-exchanged material exhibited a significantly lower number of crack deflections compared with those in the two other materials (p < 0.001). The microstructure of the two exchanged porcelain materials was dense, with well-dispersed small crystals as well as larger rubidium or cesium leucite crystals. The mean flexural strength of the rubidium-exchanged material was significantly higher than those of the other materials, which were not significantly different. It was concluded that the thermal expansion of leucite-reinforced porcelain can be lowered by ion-exchange, which also modifies the microstructure, crack deflection patterns, and flexural strength of the material.

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“…Also, ∆R is the difference in the radius of curvature of the film (or the substrate) before and after the film deposition, t s is the substrate thickness, and t f is the film thickness. The thicknesses of the substrate and film were measured by scanning electron microscopy, and the elastic moduli were taken from the literature (Table 1) [15,16].…”

Section: Methodsmentioning

confidence: 99%

Residual Stress Measurement in YBCO Thin Films

Cheon

Singh

2006

Ceramic Transactions Series

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Fracture toughness of YBa2Cu3O6+δ single crystals: Anisotropy and twinning effects

Cited by 65 publications

References 8 publications

Temperature dependence of growth orientation of YBa2Cu3O6+δ film on NdGaO3 using liquid-phase epitaxy

Temperature dependence of growth orientation of YBa2Cu3O6+δ film on NdGaO3 using liquid-phase epitaxy

Effect of Ion Exchange on the Microstructure, Strength, and Thermal Expansion Behavior of a Leucite-reinforced Porcelain

Residual Stress Measurement in YBCO Thin Films

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