We present electrical transport, magnetization, and specific heat measurements on bulk magnesium diboride (MgB2) samples (T-c = 38.5 K) synthesized under 200 MPa pressure using a process based on hot isostatic Pressing with cooling under pressure. The samples are fully dense and display excellent superconducting properties, including a narrow superconducting transition width (DeltaT(c) = 0.75 K), a high upper critical field H-c2 (H-c2(0) similar to 152 kOe), and a critical current density J(c) that is the largest yet measured for bulk samples of MgB2 (J(c)(0) similar to 1.4 MA/cm(2)). Specific heat measurements yielded a jump DeltaC at T-c of 92 mJ/mol K. These superconducting properties are comparable to those obtained with techniques that are not so well suited to industrial scale fabrication. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 18]
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