Title :
Development of low cost (Sr,Ca)3Al2O6 dielectrics for Bi2Sr2CaCu2O8+δ applications
Author :
Haugan, Timothy ; Wong-Ng, Winnie ; Cook, Lawrence P. ; Geyer, Richard G. ; Brown, Henrietta J. ; Swartzendruber, Lydon ; Kaduk, James
Author_Institution :
Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA
fDate :
3/1/2001 12:00:00 AM
Abstract :
Aspects of the development of low-cost (Sr,Ca)3Al2 O6 dielectrics for Bi2Sr2CaCu2O8+δ superconductor applications were investigated, A tie-line phase equilibrium relationship between Bi2Sr2CaCu2 O8+δ and Sr2CaAl2O6 compositions was observed at 860°C, When the Bi-2212 and (Sr,Ca)3Al2O6 solid-solution compositions were changed slightly, the tie-line relationship was not preserved, and a new phase was observed to form with composition ~BiSr 1.5Ca0.5Al2Ox. Composites of (0 to 24) volume fraction % Sr2CaAl2O6-Bi2Sr2 CaCu2O8+δ equilibrated at 860°C slightly reduced the Tc (by 2 K to 4 K) and superconducting volume percentage of the 2212 phase. The dielectric properties of (Sr=1.0 to 2.5) members of solid-solution (Sr,Ca)3Al2 O6 were measured at 77 K and 297 K in the range of (10 to 11) GHz for cylindrical samples using resonant system methods. The dielectric constant εr varied from 9.7 to 13.2, and the loss tangent tan δ was from 3×10-4 to 8×10 -4
Keywords :
bismuth compounds; calcium compounds; composite superconductors; dielectric losses; dielectric thin films; high-temperature superconductors; permittivity; phase diagrams; phase equilibrium; strontium compounds; superconducting transition temperature; (SrCa)3Al2O6-Bi2Sr 2CaCu2O8; 10 to 11 GHz; 2212 phase; 297 K; 77 K; 860 C; Bi2Sr2CaCu2O8+δ applications; BiSr1.5Ca0.5Al2Ox; Sr2CaAl2O6; Sr2CaAl2O6-Bi2Sr 2CaCu2O8+δ; Tc; composites; dielectric constant; dielectric properties; loss tangent tan δ; low cost (Sr,Ca)3Al2O6 dielectrics; superconducting volume percentage; tie-line phase equilibrium; Bismuth; Costs; Dielectric constant; Dielectric losses; Dielectric materials; NIST; Strontium; Superconducting microwave devices; Telephony; Thick films;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
