Studying the laser radiation effects on the physical properties of ZnO varistors doped with different additives /
Mohamed Yahia Elemam Helali
Studying the laser radiation effects on the physical properties of ZnO varistors doped with different additives / دراسة تأثير أشعة الليزر على الخصائص الفيزيائية لفاريستور أكسيد الزنك و المطعم باضافات مختلفة Mohamed Yahia Elemam Helali ; Supervised Mohamed Mounir Saad Eldin Mohamed , Osama Amin Mohamed Desouky , Makram Ibrahim Khalil Ibrahim - Cairo : Mohamed Yahia Elemam Helali , 2020 - 156 P. : charts , facsimiles ; 25cm
Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Science and Interactions
In this thesis work, four groups of CuO-doped ZnO varistor samples were prepared; each group consists of 9 samples with different concentrations of CuO in the range (0-6) mol%. The samples were prepared by solid-state reaction from the Calcined Oxides with CuO concentrations, the method of preparation of samples is by mixing, drying, pressing and sintering each of the four groups at different temperatures, namely; 900 C, 1000 C, 1100 C, 1200 C for 2 hours. Three samples of group (III), sintered at 1100 C were used to investigate the effects of laser irradiation for 2 min. by exposure to pulsed picosecond Nd: YAG laser beam of a spot size of 5 mm and having pulse width of 20 picosecond and output energy 80 mJ per shot; the laser system was operated at a repetition rate of 5 shots per sec., and 1064 nm wavelength. V-I characteristics of the samples in group (III), sintered at 1100 C show that they exhibit nonlinear relationship depending on the concentration of CuO inclusions in the ZnO, and this is demonstrated by values obtained for the nonlinearity coefficient . The calculated values of for group (III), sintered at 1100 C, was in the range (10-65), achieving maximum value of 65, and it occurred at CuO content of 4 mol%. These values of the nonlinearity coefficient indicate that the ZnO ceramic varistor samples are clearly varistors, because each value of them is > 5.The different proportions of the dopant constituents gave rise to different threshold voltages, nonlinearity coefficients, and leakage currents. Other electrical characteristics of the samples were measured before and after laser irradiation by covering it with a layer of silver suspension. AC frequency range (0-100) kHz at temperature range (20-170) C was applied to investigate the electrical properties
Ceramics Nonlinearity ZnO varistors
Studying the laser radiation effects on the physical properties of ZnO varistors doped with different additives / دراسة تأثير أشعة الليزر على الخصائص الفيزيائية لفاريستور أكسيد الزنك و المطعم باضافات مختلفة Mohamed Yahia Elemam Helali ; Supervised Mohamed Mounir Saad Eldin Mohamed , Osama Amin Mohamed Desouky , Makram Ibrahim Khalil Ibrahim - Cairo : Mohamed Yahia Elemam Helali , 2020 - 156 P. : charts , facsimiles ; 25cm
Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Science and Interactions
In this thesis work, four groups of CuO-doped ZnO varistor samples were prepared; each group consists of 9 samples with different concentrations of CuO in the range (0-6) mol%. The samples were prepared by solid-state reaction from the Calcined Oxides with CuO concentrations, the method of preparation of samples is by mixing, drying, pressing and sintering each of the four groups at different temperatures, namely; 900 C, 1000 C, 1100 C, 1200 C for 2 hours. Three samples of group (III), sintered at 1100 C were used to investigate the effects of laser irradiation for 2 min. by exposure to pulsed picosecond Nd: YAG laser beam of a spot size of 5 mm and having pulse width of 20 picosecond and output energy 80 mJ per shot; the laser system was operated at a repetition rate of 5 shots per sec., and 1064 nm wavelength. V-I characteristics of the samples in group (III), sintered at 1100 C show that they exhibit nonlinear relationship depending on the concentration of CuO inclusions in the ZnO, and this is demonstrated by values obtained for the nonlinearity coefficient . The calculated values of for group (III), sintered at 1100 C, was in the range (10-65), achieving maximum value of 65, and it occurred at CuO content of 4 mol%. These values of the nonlinearity coefficient indicate that the ZnO ceramic varistor samples are clearly varistors, because each value of them is > 5.The different proportions of the dopant constituents gave rise to different threshold voltages, nonlinearity coefficients, and leakage currents. Other electrical characteristics of the samples were measured before and after laser irradiation by covering it with a layer of silver suspension. AC frequency range (0-100) kHz at temperature range (20-170) C was applied to investigate the electrical properties
Ceramics Nonlinearity ZnO varistors