Study On Preparation Process And Properties Of K_0.5Na_0.5NbO₃ With Orientation Thick Films

As an important environment-friendly piezoelectric ceramic, K0.5Na0.5NbO3 has become one of the most popular studied braches of lead-free piezoelectric ceramics. With the rapid development of the drive for miniaturization and micro electro mechanical system (MEMS), the fabrication of K0.5Na0.5NbO3 thick ceramic films have been promoted for applications. In this thesis, the K0.5Na0.5NbO3 with orientation thick films were synthesized by sol-gel method and powder-sol processing. The preparation method and electric properties were discussed.The thick films were firstly synthesized by treating the firstly deposited Nb(OH)5 with C2H2O4-2H2O, then obtaining the secondly deposited Nb(OH)5 with high activity by dropping NH3-H2O which could resolve the problem of the lack of Nb source with high activity. The steady K0.5Na0.5NbO3 sol could be prepared on the base of synthesized Nb with high activity by improving techniques and reducing the CA. After above works, the small aggregated and well developed super tiny powder was prepared as well as the NaNbO3 template with (110) orientation by molten salt method.The K0.5Na0.5NbO3 thick films with (100) orientation were prepared by sol-gel method. The influences of substrate,solvent,PVP,post-treatment temperature and time as well as annealing temperature and time towards (110) orientation have been investigated, and the optimum parameters have been figured out.The K0.5Na0.5NbO3 ceramic thick films with (110) orientation were prepared by powder-sol processing.The influences of powder and NaNbO3 template towards (110) orientation have been investigated, and the optimum parameters have been figured out.The dielectric constant of K0.5Na0.5NbO3 thick films with (110) orientation prepared by powder-sol processing was larger than which was prepared by sol-gel. Meanwhile, the dielectric loss was larger than the later as well. The influence of different orientations towards dielectric property has been investigated. The ferroelectric property of K0.5Na0.5NbO3 thick films with (110) orientation prepared by powder-sol processing was not good and the leak current was relatively bigger.