Impact of damaging and recovery on the temperature dependence of the work function of oxide electrodes in fluorescent lamps

2021 ◽  
Vol 96 (1) ◽  
pp. 11301
Author(s):  
Reinhard Langer ◽  
Irina Paul ◽  
Reinhard Tidecks
Keyword(s):  
Ultraviolet Radiation ◽  
Temperature Dependence ◽  
Work Function ◽  
Surface States ◽  
Strong Increase ◽  
Thermal Excitation ◽  
Cold Starting ◽  
Fluorescent Lamps ◽  
Oxide Electrodes ◽  
Before And After

In the present work the work function of electrons for oxide cathodes in operating fluorescent lamps is measured before and after damaging the cathodes by cold starting of the lamp. A strong increase of the absolute value and a decrease of the temperature dependence of the work function is observed. The values recover partly after operating the lamp for a certain time. The results are interpreted as the consequence of a thin metallic layer generated during cold starting at the surface of the oxide and its effect on the depletion of electrons of donor-like colour centres (appearing in the oxide due to oxygen vacancies) under the ultraviolet radiation present in an operating fluorescent lamp, and on the magnitude and temperature dependence of the work function in the plated regions, invoking the patch effect to generate an averaged value of the work function, which is then assumed to be observed experimentally. Moreover, barium surface states are considered, yielding reasonable values for the not plated regions, when calculating the work function, as well for the assumption of a depletion of also these states by ultraviolet radiation, as also when only regarding a thermal excitation of the surface states applying the Fowler equation. Finally, a model of a diffusion governed dynamical equilibrium yielding a T3∕2 dependence for the donor concentration is proposed.

The temperature dependence of the work function of oxide electrodes in fluorescent lamps

2020 ◽  
Vol 92 (1) ◽  
pp. 11301
Author(s):  
Reinhard Langer ◽  
Reinhard Tidecks
Keyword(s):  
Temperature Dependence ◽  
Work Function ◽  
Surface States ◽  
Zero Field ◽  
Visual Methods ◽  
Fluorescent Lamps ◽  
Oxide Electrodes ◽  
The Impact ◽  
Field Emission Of Electrons

In the present work the temperature dependence of the work function of oxide cathodes in operating fluorescent lamps was investigated experimentally. A detailed review on the theory is presented, including a thermodynamic and a quantum mechanical view on the problem. Aspects such as the role of the electrochemical potential, external and internal potentials, the constituents of the electron affinity, the patch effect and surface states are discussed. For solids in contact the Volta and Galvani potentials are related to their work functions. The importance of colour centres in oxide electrodes on the temperature dependence of the work function and the impact of ultraviolet radiation is emphasized. The measurements have been carried out under zero field emission of electrons from the electrode, using the Waymouth (rf) and Eisenmann (visual) methods as indicators. By inserting an empirical ansatz into the Richardson equation, it was possible to determine the temperature dependence of the work function from the experiments.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Temperature dependence of the electron energy gap of highTCsuperconductors studied by work function spectroscopy

1994 ◽  
Vol 64 (13) ◽  
pp. 1726-1728
Author(s):  
S. Westermeyr ◽  
R. Müller ◽  
J. Scholtes ◽  
H. Oechsner
Keyword(s):  
Temperature Dependence ◽  
Work Function ◽  
Electron Energy ◽  
Energy Gap

scholarly journals Effect of Gamma Radiation on Characteristic of bipolar junction Transistors (BJTs )

2021 ◽  
pp. 1-9
Author(s):  
Abdenabi Ali Elamin ◽  
Waell H Alawad
Keyword(s):  
Gamma Radiation ◽  
Power Supplies ◽  
Strong Increase ◽  
Bipolar Junction Transistors ◽  
Bipolar Junction Transistor ◽  
Before And After ◽  
Junction Transistor ◽  
The Individual ◽  
Silicon Transistor ◽  
Different Doses

This paper describes the effects of 60Cogamma radiation hardness of characteristic and parameters of Bipolar Junction Transistors in order to analyze the performance changes of the individual devices used in nuclear field. Bipolar Junction Transistor (BJT) of the type (BC-301) (npn) silicon, Transistor was irradiated by gamma radiation using 60Cosource at different doses (1, 2, 3, 4, and 5) KGy. The characteristics and parameter of Bipolar Junction Transistor was studied before and after irradiated by using Transistor Characteristics Apparatus with regulated power supplies. Obtained result showed that, the saturation voltage VCE(sat) of Bipolar Junction Transistor decreased because of the gain degradation of the transistor and increased silicon resistivity, Another parameter of a bipolar junction transistor affected by ionizing radiation is a collector-base leakage current, a strong increase of the current is caused by the build-up charge near the junction.

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