Development of bimorph vibrator using lead free BNT piezoelectric film deposited by hydrothermal method
PZT piezoelectric film synthesized hydrothermally has been studied actively in our laboratory. However, it is apprehended recently that PZT affects health and the environment, because PZT is chemical compound containing lead. Therefore, we tried to synthesize lead free BNT piezoelectric film on titanium substrate hydrothermally. The synthesized BNT films on titanium substrates were evaluated with SEM image, XRD pattern and EDS. We fabricated bimorph vibrators with synthesized lead free BNT film and evaluated their performances.
Synthesis and Characterization of Piezoelectric (Bi1/2Na1/2)TiO3 Films by a Hydrothermal Method
Thin films of lead-free piezoelectric ceramics (Bi1/2Na1/2)TiO3 (abbreviated as BNT) were prepared on pure titanium substrates by a hydrothermal method. The properties of BNT films synthesized from the reaction solution with various contents of bismuth and titanium were investigated using SEM, EDX, XRD and other instruments. Moreover, the effects of the concentrations of starting materials on permittivity and piezoelectric effect of deposited BNT films were discussed. The results showed that an impurity of Bi2O3 crystal was produced on the surfaces of all deposited films. With assumption of deposited films as an system of (1-x) (Bi1/2Na1/2)TiO3-xBi2O3, the BNT content was calculated from the Bi/Ti ratio of the EDX results. The optimized synthesis condition was determined on the evaluation target of the calculated BNT content. In addition, the unimorph cantilever type actuators were fabricated by BNT deposited samples, and their piezoelectric responses were measured at their resonance frequencies under AC field. It was noted that the piezoelectric effect of the deposited BNT film was greatly dependent on its crystallization level.
Badush Dam, NW Iraq : A Geological Study
The river Tigris flows from Turkey towards Iraq in its northwestern part dissecting the whole Iraqi territory. During 1981– 1986 a very large earth fill dam was constructed, which is Mosul Dam impounding the flow of the Tigris River. It is the largest dam in Iraq and one of the largest in the Middle East. The geological conditions of the dam site and surroundings, however, are not suitable due to thick exposures of the Fatha Formation, which consists of marl, clay, limestone and gypsum. The gypsum and limestone beds are highly karstified causing severe problems to the dam foundation. Mosul dam suffers from serious problems due to the presence of karstified rocks; therefore, the Ministry of Irrigation in Baghdad, decided to construct a protection dam downstream of Mosul Dam; it is called Badush Dam. The geological conditions at Badush Dam site are the same as those at Mosul Dam site, which means the foundations of the dam are located on karstified rocks. Therefore, grouting works were planned and designed and it was partly performed from the beginning of the construction in 1988. The construction of the dam; however, stopped in 1991 due to the consequences of the First Gulf War. The constructed parts of the dam are (30 – 40) %. In this study, we have presented the main problems, which will cause real danger to Badush Dam, if its construction is re-started, and we have suggested many requirements to avoid any hazard that may cause the collapse of Badush Dam.