Work function measurements of contact materials for industrial use

Akbi, Mohammed; Lefort, A.

doi:10.1088/0022-3727/31/11/003

Cited by 42 publications

(16 citation statements)

References 27 publications

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“…Alternatively to the method of fitting Fowler isothermal curves [12], we have used the equivalent procedure of plotting the square root of the photocurrent versus photon energy [13]. Typical linearized Fowler plots, for the results in Fig.…”

Section: A Effect Of Temperaturementioning

confidence: 99%

“…The procedures of cathode heating and temperature measurements have been given in much details in [14], where Fowler's photoelectric method was used for the determination of EWF. However, as above-mentioned, instead of using Fowler isothermal curves, it is common practice to determine the EWF of metals by means of a plot of √ I versus hν, where I is the photocurrent emitted per photon absorbed and hν is the photon energy [13]. Usually, such plot yields a straight line whose intercept with the hν-axis is the EWF .…”

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confidence: 99%

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A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

Akbi¹

2014

IEEE Trans. Compon., Packag. Manufact. Technol.

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The nature of the contact material plays a key role to determine the characteristics of electrical arcs and particularly those related to electronic emission. Mechanical and thermodynamic properties as well as electronic emission of such complicated alloys present a lack of reliable and accurate experimental data. The purpose of this paper is to present the development of a method for measuring photoelectric work functions of contact materials. Also reported in this paper are the results of experimental work whose purpose has been the buildup of a reliable photoelectric system and associated monochromatic ultraviolet radiations source, and the photoelectric measurement of the EWF of contact materials. As a first test of the experimental Ultra High Vacuum setup, the electron work functions (EWF) of silver contacts, namely pure polycrystalline metals that are actually used in relays, were measured photoelectrically, using both Fowler's method of isothermal curves and linearized Fowler plots. Ultrahigh vacuum techniques were employed to obtain residual gas pressure of about 5×10 −9 mbar that allows accurate and reliable photoelectric work function measurements. The EWF measured at room temperature of polycrystalline Ag contact (as commercially available) increased from 3.70 eV before heating, to 4.30 eV, and finally, stabilized at the vicinity of 4.26 eV after several vacuum heat treatments at 533 and 773 K. The EWF value obtained, i.e., 4.26 ± 0.03 eV, is in good agreement with the results found in the literature. This shows that the experimental method is valid and the experimental setup is usable. Furthermore, new photoelectric measurements versus temperature have shown a linear decrease of the EWF of silver contacts with increasing temperature, i.e., the temperature coefficient α = dφ/d t is constant and negative α = −4.58 · 10 −4 eV/K in the experiment temperature range 300-780 K.Index Terms-Contact materials, electron work function (EWF), Fowler's Methods, photoemission, temperature dependence, vacuum heat treatment.

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Section: A Effect Of Temperaturementioning

confidence: 99%

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confidence: 99%

A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

Akbi¹

2014

IEEE Trans. Compon., Packag. Manufact. Technol.

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“…Oxygen on the other hand, will form a strong bond and dissociatively chemisorbs as atoms on the surface [13], thereby increasing the likelihood of oxide formation. It is also worth noting that the work function of both copper and zinc are lower than the surface work function when oxygen is adsorbed [14]. The behavior of SF 6 is unknown but given that it's electronegative like O 2 (much stronger so), it is assumed to dissociate and strongly bond to copper as either sulfur or fluorine.…”

Section: B Gas Comparisonmentioning

confidence: 99%

Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

Walton¹,

Leonhardt²,

Fernsler³

2006

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Pulsed hollow cathode discharges, used to generate kilovolt electron beams for the production of plasmas, were studied in low pressure (50-70 mTorr) backgrounds of argon, oxygen, nitrogen, SF 6 and mixtures thereof. Cathode currents were measured as a function of cathode voltage, duty factor, and relative gas concentration. The cathode current was found to have a dependence on all variables, with the greatest impact being operating gas for all voltages and duty factors. The ambient gas is thought to influence the production of secondary electrons at the cathode surface, thereby impacting the operation of the hollow cathode discharge and electron beam production. REPORT TYPE 1. REPORT DATE (DD-MM-YYYY) TITLE AND SUBTITLE AUTHOR(S) PERFORMING ORGANIZATION REPORT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S) 15-12-2006Memorandum Report AbstractPulsed hollow cathode discharges, used to generate kilovolt electron beams for the production of plasmas, were studied in low pressure (50-70 mTorr) backgrounds of argon, oxygen, nitrogen, SF 6 and mixtures thereof. Cathode currents were measured as a function of cathode voltage, duty factor, and relative gas concentration. The cathode current was found to have a dependence on all variables, with the greatest impact being operating gas for all voltages and duty factors. The ambient gas is thought to influence the production of secondary electrons at the cathode surface, thereby impacting the operation of the hollow cathode discharge and electron beam production.

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“…1,2 Industry is particularly interested in and is intensively researching contact charging-the main phenomenon of the electrophotographic development process [3][4][5] -involved in nonimpact, toner, and developerbased printing technologies. A large number of experimental and theoretical studies have been conducted and summarized in comprehensive reviews [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and yet the mechanism of contact electrification remains unclear.…”

Section: Introductionmentioning

confidence: 99%

“…By comparing the work functions of the materials in contact, it is possible to characterize tribopairs and to establish a triboelectric series. 3,20,21 However, it is difficult to reproduce even simple experiments due to variations in the ambient atmosphere, including dust, chemical impurities and humidity, and due to noncontrollable alterations of the surfaces during contact. 4,25 An alternative approach involves the use of theory and computation to describe the contact charge.…”

Section: Introductionmentioning

confidence: 99%

Electron Transfer in Electrical Tribocharging Using a Quantum Chemical Approach

Nikitina¹,

Barthel²,

Heinemann³

2009

jist

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Electrical tribocharging is a fundamental physicochemical phenomenon and the basis of electrophotographic development. Despite extensive study, a complete understanding of the mechanism-commonly referred to as electron or ion transferremains unclear. Using a quantum chemical (QCh) approach, we studied the electron charge transfer (ECT) as one possible atomicscale mechanism of tribocharging. We also describe ECT for several systems based on two materials in contact (tribopairs). Methods of density function theory and time-dependent density function theory were applied to QCh modeling using a cluster approach. A series of energetic and charge characteristics at the atomic level were calculated: including the highest-and lowest-occupied molecular orbitals (respectively) and the Fermi levels of complex components in their individual (free) as well as contact states, before and after electron excitation, ECT-excited energy states, charge distribution in the complexes, and the dipole moments of the excited complexes with ECT. Correlations were evaluated between the transferred charges and dipole moments and between transferred charges and Fermi levels. Furthermore, we could show that the QCh analysis offers insight into the ranking of tribocharging agents based on their chemical nature.

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Work function measurements of contact materials for industrial use

Cited by 42 publications

References 27 publications

A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

A Method for Measuring the Photoelectric Work Function of Contact Materials Versus Temperature

Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures

Electron Transfer in Electrical Tribocharging Using a Quantum Chemical Approach

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