Mechanical and Structural Properties of Graphene Oxide and Reduced Graphene Oxide Doped YBCO

Abstract

YBCO (Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> ) was doped with graphene oxide (GO) and reduced graphene oxide (rGO) in the following percentage weight concentrations: 0.1, 0.5 and 1% wt.. Lattice parameters, crystallite size, orthorhombicity and lattice strain were calculated using XRD analysis. The porosity of samples decreased by a maximum of 29% and 17% for GO and rGO doped samples respectively. Microhardness measurements were conducted using the Vickers hardness method at loads in the range of 0.245 - 2.940 N. These micro hardness measurements were used to calculate the Vickers hardness ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_V</i> ), elastic modulus ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> ), yield strength ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> ), fracture toughness ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K_IC</i> ) and brittleness index ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> ) of the material. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_V</i> was greater in GO doped samples than in rGO doped samples. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> increased by 63.94% for rGO and 85.52% for GO doped samples. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> increased by 63.80% for rGO and 85.40% for GO doped samples. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> decreased by 48.11% for rGO and 43.78% for GO doped samples. There was an increase in K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IC</sub> for both GO and rGO samples. The indentation size effect (ISE) was observed during micro-hardness measurements. This ISE behaviour was analyzed using Meyers Law, PSR model, elastic/plastic deformation model and Hays Kendall model. The results showed that the Hay Kendall approach best described the ISE behaviour of the samples.