Search for Novel Superconductors, Thermoelectrics, and Super Thermal Conductors with Enhanced Performance
Abstract
To meet the needs of the Department of Defense for national defense and security, and at the same time to promote the health and wealth of our national economy, we have proposed, during this grant period, to search for novel materials in three areas: A) superconductors with higher Tc, higher Jc, and reduced anisotropy; B) thermoelectric materials with high figures of merit and power factors; and C) super-thermal-conductors or solids with giant thermal conductivity. During this grant period, we have: 1) achieved by thermal annealing and confirmed by microstructure study, for the first time, superconductivity up to 25 K induced through interphases between two non-superconducting allotropes of CaFe2As2, demonstrating directly a new path to high Tc via interfacial effect as predicted almost five decades ago; 2) brought down by high pressures the Tc-limits imposed by the so-called universal inverse quadratic Tc-carrier rule and brought the Tc to new heights without any sign of saturation up to ~60 GPa for the layered high Tc cuprate superconductors, e.g. Bi2Sr2Can-1CunO2n+4 and HgBa2Can-1CunO2n+2+x, demonstrating that the current record high Tcs of stable cuprate superconductors can be further enhanced and that a new avenue to higher Tc is possible; 3) induced, by pressure, superconductivity in a Mn-compound, MnSe, up to 9 K at 35 GPa, demonstrating that Mn-containing compounds are not absolutely detrimental to superconductivity and opening up a new testing ground for possible high Tc via optimization of multiple interactions in the multiferroic materials, which often contain Mn-ions; 4) discovered and synthesized > 10 new superconducting compounds with interesting electronic structures although with low Tcs < 8 K, some of which were through novel synthesis routes that may be deployed to high Tc superconductor preparations...
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 19, 2021
- Accession Number
- AD1121628
Entities
People
- Paul C. Chu
Organizations
- University of Houston System