A systematic study on phase evolution, bulk density, resistivity, critical transition temperature (T C ), critical current density (J C ) and in-field transport critical current density (J C -B) of pure and nano particles of BaHfO 3 added YBa 2 Cu 3 O 7−δ (YBCO) samples of different weight percentages has been carried out. The result shows a significant improvement in the electrical transport properties of the superconductor, namely the J C , J C -B characteristics and flux pinning force (F p ) of the BaHfO 3 added samples. The transition temperature also was found to increase marginally. A maximum transport J C of 742 A/cm 2 at 77 K (for x = 2 wt%) was observed for BaHfO 3 added samples against 147 A/cm 2 for pure YBCO sample. The enhancement of the critical current density in the YBCO-BaHfO 3 sample is attributed to the formation of an insulating and non-reacting YBa 2 HfO 5.5 phase, acting as artificial pinning centers in the matrix. The introduction of nano particles of BaHfO 3 in bulk YBCO increases the pinning force density from 30 × 10 3 N/m 3 to 424 × 10 3 N/m 3 at 77 K. The improvement in sintering density due to an optimum value 2 wt% BaHfO 3 addition in bulk YBCO indicates its potential use in electrical devices and technology. The enhancement in the superconducting properties, particularly in the J C -B characteristics due to BaHfO 3 addition, seems to have great technological significance.

The effect of addition of different weight percentages of nanocrystalline HfO2, synthesized through a modified combustion method in bulk coarse‐grained orthorhombic YBa2Cu3O7−δ powder was studied. The structure and microstructure of the samples examined by X‐ray diffraction (XRD) and scanning electron microscopy (SEM) showed the formation of a secondary phase YBa2HfO5.5 in the superconductor without deteriorating the superconducting properties. The variation of sintering temperature, density, critical transition temperature (Tc), magnetic field dependence of critical current density (Jc), and flux‐pinning force (Fp) of YBa2Cu3O7−δ having different proportions of YBa2HfO5.5 formed in the matrix were studied in detail. The samples showed a transition temperature (Tc) of ∼92 K and the self‐field critical current density (Jc) increases significantly up to an optimum value of 5.42 × 104 A cm−2 for 2 wt% addition of nano HfO2. The enhancement of the critical current density in the YBa2Cu3O7−δ‐HfO2 samples is attributed to the presence of the nonreacting YBa2HfO5.5 phase, formed due to the addition of HfO2 as artificial pinning center. The formation of YBa2HfO5.5 in YBa2Cu3O7−δ bulk superconductor also enhances the pinning force density from 3 × 106 to 30.4 × 106 N m−3 at 77 K.

J C) should be read as MA/m 2 (mega ampere per metre square) instead of A/cm 2 and the magnitude of Flux pinning force density (F p) should be multiplied with 10 5 instead of 10 3 wherever it is repeated in the manuscript including the figures and tables. This change in the unit of J C and the magnitude of F p will not affect any discussions in this paper.

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