Spectroscopic emission of lead plasma, generated by the fundamental （1064 nm） and second harmonics （532 nm） of a Q-switched pulsed Nd： YAG laser, is studied. The spectral lines of neutral atoms and singly ionized...Spectroscopic emission of lead plasma, generated by the fundamental （1064 nm） and second harmonics （532 nm） of a Q-switched pulsed Nd： YAG laser, is studied. The spectral lines of neutral atoms and singly ionized lead ions were shown predominantly. The profiles of neutral lead lines observed were used to extract the excitation temperature using Boltzmann plots, whereas electron number density was determined from the profile of Stark broadened line. The variations of excitation temperature and electron number density as a function of laser energy were studied.展开更多
Lead-free piezoelectric （K0.5sNa0.5）1-xLixNbO3 （x = 0at%-20at%） ceramics were synthesized by spark plasma sintering （SPS） at low temperature and the effects of LiNbO3 addition on its crystal structure and proper...Lead-free piezoelectric （K0.5sNa0.5）1-xLixNbO3 （x = 0at%-20at%） ceramics were synthesized by spark plasma sintering （SPS） at low temperature and the effects of LiNbO3 addition on its crystal structure and properties were also studied. When the Li content was less than 6at%, a single proveskite phase with the similar structure of （K0.5Na0.5）NbO3 was formed; and a secondary phase with K3Li2Nb5O15 structure was observed in the 6at% 〈 x 〈 20at% compositional range. Furthermore, LiNbO3 existed as the third phase when the Li content was higher than 8at%. The grain sizes increased from 200-500 nm to 5-8 μm when the K3Li2Nb5O15 and LiNbO3 like phases were formed. With increasing Li content, the relative density of the ceramics first decreased from 97% to 93% and then kept constant. The piezoelectric coefficient d33, dielectric constant, and planner electromechanical coupling factor exhibited a decreasing tendency with increasing Li content because of the decrease in density and the formation of the secondary phase such as K3Li2Nb5O15 and LiNbO3. The formation of dense microstructure with a single phase is necessary in improving the properties of the （K0.5Na0.5）1-xLixNbO3 ceramics.展开更多
基金financially supported by the Higher Education Commission (HEC) and Pakistan Science Foundation (PSF-134)MCS, National University of Sciences & Technology (NUST) for encouragement in terms of provision of time and financial support to carry out research work
文摘Spectroscopic emission of lead plasma, generated by the fundamental （1064 nm） and second harmonics （532 nm） of a Q-switched pulsed Nd： YAG laser, is studied. The spectral lines of neutral atoms and singly ionized lead ions were shown predominantly. The profiles of neutral lead lines observed were used to extract the excitation temperature using Boltzmann plots, whereas electron number density was determined from the profile of Stark broadened line. The variations of excitation temperature and electron number density as a function of laser energy were studied.
文摘Lead-free piezoelectric （K0.5sNa0.5）1-xLixNbO3 （x = 0at%-20at%） ceramics were synthesized by spark plasma sintering （SPS） at low temperature and the effects of LiNbO3 addition on its crystal structure and properties were also studied. When the Li content was less than 6at%, a single proveskite phase with the similar structure of （K0.5Na0.5）NbO3 was formed; and a secondary phase with K3Li2Nb5O15 structure was observed in the 6at% 〈 x 〈 20at% compositional range. Furthermore, LiNbO3 existed as the third phase when the Li content was higher than 8at%. The grain sizes increased from 200-500 nm to 5-8 μm when the K3Li2Nb5O15 and LiNbO3 like phases were formed. With increasing Li content, the relative density of the ceramics first decreased from 97% to 93% and then kept constant. The piezoelectric coefficient d33, dielectric constant, and planner electromechanical coupling factor exhibited a decreasing tendency with increasing Li content because of the decrease in density and the formation of the secondary phase such as K3Li2Nb5O15 and LiNbO3. The formation of dense microstructure with a single phase is necessary in improving the properties of the （K0.5Na0.5）1-xLixNbO3 ceramics.
