N. Sivakumar

Preparation of thin film of CaZrO3 by pulsed laser deposition

Abstract Thin films of CaZrO 3 are prepared by pulsed laser deposition (PLD) using a 532-nm Q-switched Nd:YAG laser. Films prepared in vacuum, on annealing, revealed the structure of calcia stabilized zirconia, i.e. Ca 0.15 Zr 0.85 O 1.85 . Films prepared in the presence of 150×10 −3 Torr of oxygen, on annealing, have CaZrO 3 structure, though a small percentage of Ca 0.15 Zr 0.85 O 1.85 is still present. Larger oxygen pressures during film deposition lead to the presence of many other oxides of a greater oxygen mole fraction in the film. Particulate deposition that leads to undesirable properties for the films is observed in the scanning electron microscopy (SEM) when the film is prepared using a laser fluence of the order of 16 J/cm 2 , whereas the fluence 0.64 J/cm 2 produced particulate-free films. The vapor composition and the velocities of the different species (in vacuum) are determined using a quadrupole mass spectrometer (QMS), and the laser ablation process under the film deposition condition (laser fluence 0.64 J/cm 2 ) is found to be thermal. The deficiency in Ca observed for the film prepared in vacuum appears to correlate with a deficiency in CaO + . The observed difference in the stoichiometry of the films deposited under vacuum and oxygen background is discussed based on the mass spectrometry results.

Laser induced vaporization mass spectrometric studies on UO2 and graphite

Abstract A Nd-YAG laser system operated in the Q-switched mode was used to generate vapour plume on UO 2 and graphite targets. The vapour species formed were analysed by a quadrupole mass filter. The time resolved spectrum was obtained for each of the observed vapour species, namely, O, U, UO, UO 2 and UO 3 over UO 2 and C 1 to C 5 over graphite. Time of arrival (TOA) spectra were obtained as a function of laser power density. These TOA data are fitted by the shifted Maxwell Boltzmann distributions so as to obtain the translational temperatures and velocities of the vapour species present in the plume.

Laser induced vaporization mass spectrometric studies on Si3N4

Abstract An Si 3 N 4 sample was irradiated with an Nd-YAG laser. The species present in the plume were detected by a quadrupole mass spectrometer (QMS). The species observed were Si, SiN, Si 2 , Si 2 N, Si 3 , Si 3 N, Si 4 , Si 3 N 4 , Si 6 , Si 7 , and N. Weak signals were observed at m/e = 126 and 280. The analysis of the velocity of the different species indicates the existence of thermal equilibrium in the vaporization process.