Anil Tumuluri; K. C. James Raju
Abstract
Mono phase LiNb3O8 (LN), a compound that comes during the processing of LiNbO3 is synthesized as thin films using sol gel process followed by microwave annealing. Initial studies like phase determination, structure and microstructure of this particular compound are done. XRD pattern confirmed LN as monoclinic ...
Read More
Mono phase LiNb3O8 (LN), a compound that comes during the processing of LiNbO3 is synthesized as thin films using sol gel process followed by microwave annealing. Initial studies like phase determination, structure and microstructure of this particular compound are done. XRD pattern confirmed LN as monoclinic with no preferred orientation. From Raman spectroscopy, we found that crystallization is not uniform and new peaks are appearing. Untraceable phases have been identified from Raman imaging. The broadening of peak width is increasing with increase in temperature. Low frequency modes are due to the Li deficiency sites occupied by Nb ions and higher frequency peaks are due to oxygen displacement. Non stoichiometric phases can be identified from color contrast in Raman imaging. Microwave annealing is a successful method to obtain LiNb3O8 thin films.
A. Rambabu; Anil Tumuluri; K.C. James Raju
Abstract
Nanoindentation technique has been used to determine the mechanical properties of bismuth layered structure ferroelectric thin films, which have been shown to be promising for MEMS based devices used in sensing, actuation and energy harvesting, especially at elevated temperatures. SBTi (SrBi4Ti4O15) ...
Read More
Nanoindentation technique has been used to determine the mechanical properties of bismuth layered structure ferroelectric thin films, which have been shown to be promising for MEMS based devices used in sensing, actuation and energy harvesting, especially at elevated temperatures. SBTi (SrBi4Ti4O15) is a promising layered ferroelectric material and thin films of this composition are deposited on amorphous fused silica substrates by rf sputtering technique varying the substrate temperature from 600–725 o C. The crystal structure and surface morphology of SBTi thin films are characterized by X-ray diffraction and atomic force microscopy. Depth- sensing nanoindentation system is used to measure the mechanical characteristics of SBTi thin films. Nanoindentation measurements reveal that the Young’s modulus and hardness of SBTi thin films are related with grain size and crystal orientation which in turn depend on substrate temperature. The increase in mechanical properties with grain size is observed, indicating the reverse Hall-Petch effect. Furthermore, hardness and Young’s modulus of the (119) oriented films were higher than those of (0010) oriented films. The tribological properties of these films are confirmed by performing the scratch tests on the same films.
