| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
V_3(Si,N), V_3(Si,B) compounds were attempted to be prepared by a low pressure gas plasma melting method. Compounds consisting of one fo V_3Si, V_3(Si,C) and V_3(Si,B) phases could be obtained by the above mentioned method.
The dependence of the normal-superconducting transition temperature, Tc on silicon concentration in the V_3Si and V_3(Si,B) phases has been investigated in the connection with lattice parameter and with degree of order of A-15 type of structure. Both T_c and degree of order decrease and lattice parameter increases linearly with decreasing silicon concentration in V_3Si and V_3(Si,B) phases from the stoichiometry to about 19 at % Si. The increase in the lattice parameter causee drop in T_c due to the decrease in Debye temperature, and the decrease in the degree of order causes drop in T_c due to the decrease in the electron density of states at ferumi surface.
Addition of about 0.5 at% boron to the V_3 Si phase brings about rise in T_c by 1-5 K in the range from 25 to 19 at% Si. The amount of the rise in T_c is about 1 K at the stoichiometry and reaches to about 5 K at 19 at% Si. The rise of T_c by addition of small amount of boron is mainly due to the decrease in lattice parameter of A-15 type of structure.
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