Fracture toughness of YBa sub 2 Cu sub 3 O sub 6+. delta. single crystals: Anisotropy and twinning effects

Journal Article · Fri Nov 15 04:00:00 EST 1991 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.350234· OSTI ID:5053260

Raynes, A S; Freiman, S W; Gayle, F W; Kaiser, D L ^[1]

---

1. Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland (USA)

Indentation/crack length measurements were used to determine hardness and fracture toughness in twinned and detwinned single crystals of YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} (YBCO). Hardness was found to be isotropic and unaffected by twin boundaries or moisture; the average hardness value was 9.5 GPa. Fracture toughness ({ital K}{sub {ital c}}) 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 {ital K}{sub {ital c}} between the {ital a} and {ital b} directions. Twin boundaries were found to toughen YBCO, enhancing {ital K}{sub {ital c}} by about 25%. Moisture promoted crack growth, degrading {ital K}{sub {ital c}} by about 35%.

• OSTI ID: 5053260
• Journal Information: Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 70:10; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
AMINES
AMMONIUM COMPOUNDS
ANISOTROPY
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
FRACTURE PROPERTIES
HARDNESS
HIGH-TC SUPERCONDUCTORS
MECHANICAL PROPERTIES
MOISTURE
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
QUATERNARY COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
TWINNING
YTTRIUM COMPOUNDS
YTTRIUM OXIDES