Title: Filamentary superconductivity in semiconducting policrystalline ZrSe2 compound with Zr vacancies,
Abstract: ZrSe2 is a band semiconductor studied long time ago. It has interesting
electronic properties, and because its layers structure can be intercalated
with different atoms to change some of the physical properties. In this
investigation we found that Zr deficiencies alter the semiconducting behavior
and the compound can be turned into a superconductor. In this paper we report
our studies related to this discovery. The decreasing of the number of Zr atoms
in small proportion according to the formula ZrxSe2, where x is varied from
about 8.1 to 8.6 K, changing the semiconducting behavior to a superconductor
with transition temperatures ranging between 7.8 to 8.5 K, it depending of the
deficiencies. Outside of those ranges the compound behaves as semiconducting
with the properties already known. In our experiments we found that this new
superconductor has only a very small fraction of superconducting material
determined by magnetic measurements with applied magnetic field of 10 Oe. Our
conclusions is that superconductivity is filamentary. However, in one studied
sample the fraction was about 10.2 %, whereas in others is only about 1 % or
less. We determined the superconducting characteristics; the critical fields
that indicate a type two superonductor with Ginzburg-Landau ? parameter of the
order about 2.7. The synthesis procedure is quite normal fol- lowing the
conventional solid state reaction. In this paper are included, the electronic
characteristics, transition temperature, and evolution with temperature of the
critical fields.