Effects of substrates on the NdBa2Cu3O7-δ films fabricated by the PLD process

NdBa2Cu3O7-δ (NdBCO) films were grown by pulsed-laser deposition (PLD) on SrTiO3 (STO)(1 0 0), MgO(1 0 0), and STO-buffered MgO(1 0 0) substrates for a comparative study on the effect of substrate on the textures, microstructures, and superconducting properties of NdBCO films. All NdBCO films were deposited at the same substrate temperature of 800 deg. C under the same total pressure of 800 mTorr with 1%O2/Ar gas. The transport J c value of 3.5 MA/cm2 at 77 K in self-field was obtained from the NdBCO/STO with T c value of 91.2 K, while the NdBCO/MgO with T c of 86.8 K exhibited the low J c value of 0.25 MA/cm2. On the other hand, J c value of 1.55 MA/cm2 was obtained from NdBCO film on STO-buffered MgO(1 0 0) substrate with T c of 91.5 K. The higher J c value of the NdBCO/STO than NdBCO/STO/MgO resulted from much better in-plane and out-of-plane textures of NdBCO/STO, while the low J c value of the NdBCO/MgO can be attributed to both depressed T c value and the existence of 45 deg. -rotated grains with [0 0 1]NdBCO parallel [1 1 0]MgO