Accession Number : ADA321849

Title :   Low Loss Substrates for Microwave Applications and Sol-Gel Processing of Superconductors.

Descriptive Note : Final rept. 1 Apr 94-25 Sep 96,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB

Personal Author(s) : Cross, L. E. ; Roy, Rustum ; Bhalla, Amar S.

PDF Url : ADA321849

Report Date : SEP 1996

Pagination or Media Count : 87

Abstract : This document is a final technical report of the research program entitled 'Low Loss Substrates for Microwave Applications and Sol-Gel Processing of Superconductors. Systematic studies on low K oxide substrate materials suitable for epitaxial deposition of high Tc superconducting (HTSC) yttrium barium cuprate (YBCO) films and their microwave applications have been extended to oxide materials with magnetoplumbite structure, such as LaMgAl11O19, NdGaMgAl10O19, CaGa6Al6O19, and CaGa12O19. The unique capabilities of a laser heated pedestal growth (LHPG) system have been utilized for test growth of candidate materials in single crystal fiber form to determine structure, thermal, and dielectric properties and to make positive identification of twin free systems. Dielectric properties, thermal expansion coefficients, melting temperatures and growth feasibility were tested. Through successful collaboration thorough tests on the compatibility of the SAT films as buffer layer in MgO/YBCO system have been performed. Excellent epitaxial YBCO films with Jc of 10(exp 6) A/cu cm were reproducibly obtained. Mechanisms relating the bonding nature and the order disorder in complex perovskite niobates and tantalates that governing the characteristics of their dielectric properties were studied through collaboration with the microprobe Raman spectroscopy groups. Work on the Shannon ion polarizability model for predicting dielectric permittivity in solids is being continued. Newly compiled normalized ion polarizabilities which take into consideration apparent bonding strengths improve the predictive capability considerably.

Descriptors :   *PRODUCTION ENGINEERING, *MICROWAVE EQUIPMENT, *SOL GEL PROCESSES, RAMAN SPECTROSCOPY, SINGLE CRYSTALS, EPITAXIAL GROWTH, SEMICONDUCTOR DEVICES, DIELECTRIC PROPERTIES, LOW LOSS, FEASIBILITY STUDIES, HIGH TEMPERATURE SUPERCONDUCTORS, MICROPROBES, COPPER OXIDES, PEROVSKITES, TANTALATES.

Subject Categories : Mfg & Industrial Eng & Control of Product Sys
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE