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

Indentation/crack length measurements were used to determine hardness and fracture toughness in twinned and detwinned single crystals of YBa2Cu3O6+δ (YBCO). Hardness was found to be isotropic and unaffected by twin boundaries or moisture; the average hardness value was 9.5 GPa. Fracture toughness (K...

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Veröffentlicht in:	Journal of applied physics 1991-11, Vol.70 (10), p.5254-5257
Hauptverfasser:	RAYNES, A. S, FREIMAN, S. W, GAYLE, F. W, KAISER, D. L
Format:	Artikel
Sprache:	eng
Schlagworte:	Condensed matter: structure, mechanical and thermal properties Exact sciences and technology Fatigue, brittleness, fracture, and cracks Mechanical and acoustical properties of condensed matter Mechanical properties of solids Physics
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Zusammenfassung:	Indentation/crack length measurements were used to determine hardness and fracture toughness in twinned and detwinned single crystals of YBa2Cu3O6+δ (YBCO). Hardness was found to be isotropic and unaffected by twin boundaries or moisture; the average hardness value was 9.5 GPa. Fracture toughness (Kc) was determined to be anisotropic with the average value for cracks running perpendicular to the basal plane being approximately twice that of cracks parallel to the basal plane; thus, cleavage is easier along basal planes. In addition, the results suggest a small but measurable anisotropy in Kc between the a and b directions. Twin boundaries were found to toughen YBCO, enhancing Kc by about 25%. Moisture promoted crack growth, degrading Kc by about 35%.
ISSN:	0021-8979 1089-7550
DOI:	10.1063/1.350234