Work functions of rhenium and tungsten determined by thermionic and mass spectrometric measurements
Measurements were made of the changes in the effective work function of polycrystalline W, Re, and W- Re alloys at high temperatures, as a function of the ambient oxygen pressures in the range of 10/sup -8/ to 10/sup -5/ torr. The observed work function changes were determined by two techniques: (1) the standard thermionic emission method, utilizing Richardson' s equation and (2) a mass spectrometric method wherein the positive ion emission rates of the specimen were monitored as a function of specimen temperature. In this latter method, calculations were made on the basis of the Saha-- Langmuir equation that relates ion emission rates to the ionization potential, work function. and absolute temperature of the sample. Data from both methods in the temperature range 1700 to 2150 deg K yielded consistent work function values for the pure metals. A maximum work function increase abeut 0.7 eV was noted for both W and Re at 1710 deg K at 10/sup -5/ torr, compared to a 10/sup -8/ torr reference. In the case of the alloys, there is a large difference in the effective work function change as determined by thermionic and mass spectrometric measurements. Ion emission is dominated by the high work function element, while electron emission is dominated by the low work function element. (9 figures) (auth)
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-021550
- OSTI ID:
- 4349903
- Journal Information:
- J. Mass Spectrom. Ion Phys., v. 12, no. 5, pp. 423-432, Journal Name: J. Mass Spectrom. Ion Phys., v. 12, no. 5, pp. 423-432; ISSN JMSIA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
*RHENIUM-- WORK FUNCTIONS
*TUNGSTEN BASE ALLOYS-- WORK FUNCTIONS
*TUNGSTEN-- WORK FUNCTIONS
MASS SPECTROSCOPY
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
OXYGEN
PRESSURE DEPENDENCE
TEMPERATURE DEPENDENCE
THERMIONIC EMISSION
VERY HIGH TEMPERATURE