Accession Number:

AD0920868

Title:

Radiation and Thermally Hardened Switching Materials.

Descriptive Note:

Semi-annual rept. no. 3, 1 Jul-30 Dec 73,

Corporate Author:

BELFER GRADUATE SCHOOL OF SCIENCE NEW YORK

Personal Author(s):

Report Date:

1974-06-01

Pagination or Media Count:

11.0

Abstract:

A set of systematic measurements were performed on NbO2 based crystals and powders. The possibility of stress induced switching was explored, by applying to NbO2 single crystals a piezoelectric AC stress. The result, although negative is not necessarily conclusive. Based on the assumption that the switching proceeded via a surface phenomena, powder samples were prepared, both of pure NbO2 and of NbO2 diluted with Ti2O3, V2O3, Bi2O3, and ZnO. Initial switching was observed in several samples, but the devices rapidly deteriorated under repetitive pulsing. Threshold of about 300 volts were observed. A series of single crystals of compositions Nb sub 1-X Ti sub X O2 with O or X or o.3 were prepared and their resistivities measured. Reasonable agreement was found with the measurements reported by Sakata et al. in polycrysyalline samples. The resistivities were found to be lower in all cases than that of pure NbO2. The Nb sub 1-X Ti sub X O2 samples did not show improved switching. As a continuation of the alloying approach, NbO2 single crystals doped with V, Cr, Mn, Fe, Co, Ni, Zn, Mo, and W were prepared. Dopant concentrations reached up to 5. All dopants lowered the resistivity but did not improve switching. Similar results were observed in crystals doped with In, Si, Ge and Pb, whereas no doping was possible with Sn. In the case of anionic dopants, we successfully doped NbO2 with Nitrogen. This was the only case in which an increase in resistivity was observed, but not improved switching.

Subject Categories:

  • Electrical and Electronic Equipment
  • Ceramics, Refractories and Glass
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE