Superconducting and Vickers hardness properties of ZnO‐added YBCO polycrystalline superconductors

Abstract

The effects of ZnO addition on the microstructure and mechanical properties of the YBCO have been investigated through XRD, SEM, EDX, ac susceptibility measurements and the standard Vickers microhardness testing method. We have prepared the samples by a conventional solid-state reaction method and used an additive method for the YBCO system (0, 0.5 and 1 wt% of ZnO). The orthorhombic strain ∆ = (b -a)/(b + a) increases as the Zn content increases, where a and b are the relevant lattice parameters of the samples. The superconducting transition temperatures and hardness depend on the Zn content of the samples. The hardness is found to be load dependent. From the relation between applied load F and the square of the impression diagonal, d 2 , the true hardness, H 0 , and the dissipative portion of the indentation load F 0 , were derived from the slope and the intercept (at d 2 = 0) of the straight line, respectively. The hardness was increased while the transition temperature decreased with the amount of ZnO addition to YBCO.

An analysis of load-depth data in depth-sensing microindentation experiments for intermetallic MgB2

“…Since hardness is accepted as an inherent material property, it should not vary with indentation load (or size). However, investigations [28][29][30][31] have confirmed that microhardness of various bulk materials were indentation size dependent especially at lower peak loads. In our case, Vickers microhardness values of the MgB 2 specimen also show load dependent behavior (Fig.…”

Physical and Mechanical Properties of B2O3 doped YBaCuO Superconductors: Applicability as a Low DC Magnetometer

“…Experimental set up for the second harmonic measurements were described in [4,5]. The electronics and the test conditions are explained in [4].…”

Effect of dc bias field superimposed with ac field amplitudes on the hysteresis loss in a sintered YBCO superconductor

“…The powders of Y 2 O 3 , BaCO 3 , and CuO were thoroughly mixed in the appropriate amounts and calcined at 940 • C for 24 h. After calcination, the powders were mixed by a grinding machine for 4 h and then pressed into pellets of 13 mm diameter at 375 MPa. The pellets were sintered at 945 • C for 24 h and cooled down to room temperature at a cooling rate of 1 • C/min by flowing oxygen at temperatures between 700 and 250 • C. Details on the microstructure of the sample can be found elsewhere [11].…”