We measured directly by neutron diffraction the axial and lateral residual strains for the prebent and the as-reacted CuNb∕Nb3Sn wires at room temperature and at 7K, in order to investigate the change of the residual strain with prebending treatment. In the axial direction of the wire, the residual strain was changed with 0.20% to the tensile side when measured at both temperatures, while in the lateral direction, the change was 0.08% and 0.03% to the compressive side for the measurements at RT and 7K, respectively. From the obtained data, we estimated the deviatoric strain. At 7K, the value is 0.40% for the as-reacted wires and it reduces to 0.19% when the prebending is applied with a strain εpb=0.8%. These results suggest that the reduction of the residual strain in the axial direction as well as in the lateral direction, i.e., of the deviatoric strain is responsible for the observed enhancement in the superconducting properties of the prebent Nb3Sn wires. In addition, we succeeded in the quantitative evaluation of the deviatoric strain dependence of the upper critical field for the practical Nb3Sn wire. This is very important for the understanding of the general axial strain dependence of the superconducting properties.
The crystal structures of deuterated glycinium phosphite crystals with various deuterium concentrations x (0.00, 0.25, 0.50, 0.75 and 1.00) in the paraelectric phase were determined using the X-ray imaging plate diffractometer. The hydrogen bond distances increase with increasing deuterium concentration x, especially including the disordered hydrogen atom. There is a linear relation between the transition temperature T C and the hydrogen bond distance R O{O . The critical bond length r c was estimated as 2.415 # A. HPO 3 tetrahedron rotates by duteration.
Heat capacity of glycinium phosphite was measured by adiabatic calorimetry in a temperature range from 90 K to 300 K. A -type anomaly characteristic of the second order phase transition was observed at 224.3 K (T C ). The jump of the heat capacity at T C is estimated as Ác ¼ 7:1 AE 0:2 J K À1 mol À1 . The transition enthalpy and transition entropy were estimated as ÁH ¼ 82:20 AE 0:07 J mol À1 and ÁS ¼ 0:40 AE 0:01 J K À1 mol À1 respectively. Thermal expansions of the crystal were also measured along the crystallographic a, b and c axes using the strain gages. The volume thermal expansion shows clear anomaly at T C . The jump of thermal expansion coefficient at T C is estimated as Á v ¼ À2:7 AE 0:3 Â 10 À5 K À1 .
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