Effects of Sintering Behavior on Structure and Properties of B2O3 doped (Bi0.5Na0.5)0.94Ba0.06TiO3 Lead-Free Ceramics Ms. SUPALAK MANOTHAM Department of Physics and Materials science, Faculty of Science, Chiang Mai University

Outline Introduction Experimental Results and discussions Conclusion

Introduction Piezoelectric Materials  Pierre and Curie (1880) Sensor There are two different effects, direct and converse effect, which can describe this phenomenon Sensor Actuator Mechanical stresses Electrical Potential Electric Field Mechanical Strain Direct effect convert effect

Introduction Lead-based piezoelectric materials, represented by PZT are the most widely used for piezoelectric transformer, actuator, sensor and multilayered capacitor www.reason..com www.indiabizclub.com www.rdpe.com/za/spt-stje.htm

Introduction However, lead-based piezoelectric materials contain large amount of PbO, (60 - 70% by weight) PbO Highly toxic Causes a crucial environmental problem Strongly harmful for human health

Introduction The development of environment friendly lead-free piezoelectric material has been required LEAD –FREE FRIENDLY To the EARTH ENVIRONMENTAL SCIENCE http://www.knowledgebasepublishers.org/ENV%20SCI.html Excellent properties  Comparable with the properties found in lead-based ceramics

Cause many problems during poling process Literature Review Bismuth Sodium Titanate  (Bi0.5Na0.5)TiO3 It displays a strong ferroelectricity at room temperature  Large Pr  38 C/cm2  High Curie temperature, Tc  320C However, this material has many drawbacks  High coercive field, Ec  73 kV/cm  High conductivity Cause many problems during poling process

In order to develop new lead-free material system Literature review… In order to develop new lead-free material system (1-x)Bi0.5Na0.5TiO3–xBaTiO3 (Bi0.5Na0.5)0.94Ba0.06TiO3 2 wt. % B2O3 doped BNBT High dielectric performance

Ceramics characterization Experimental Modified BNBT 2 wt. % B2O3 doped BNBT (Bi0.5Na0.5)0.94Ba0.06TiO3 Conventional mixed oxide Calcined Powders BNKT powder  800 C/2h Sieve and pressure BNBT- 2 wt. % B2O3 Ceramics Ceramics characterization BNBT- 2 wt. % B2O3 Sintering Temp: 1000-1150C Time: 2 h Rate: 5C/min

Experimental Phase Physical Dielectric Ceramics Characterization

Results and discussion XRD  BNBT doped B2O3 Ceramics Fig. 1 X-ray diffraction patterns of the ceramics sintered at various temperatures.

Results and discussion Fig. 2 Plots of density and porosity values of the ceramics sintered at different sintering temperatures.

Results and discussion Dielectric Properties  BNBT doped B2O3 Ceramics Fig. 3 Room temperature dielectric constant (εr) as a function of frequency for the samples sintered at different sintering temperatures.

Results and discussion Dielectric Properties  BNBT doped B2O3 Ceramics Fig. 4 Room temperature dielectric loss (tan δ) as a function of frequency for the samples sintered at different sintering temperatures.

Results and discussion Dielectric Properties  BNBT doped B2O3 Ceramics Fig. 5 Dielectric constant and dielectric loss as a function of temperature and frequency of the ceramics sintered at various sintering temperature.

Conclusion In this work, lead-free B2O3 doped (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics were successfully synthesized by a simple conventional mixed-oxide and ordinary sintering method. The ceramic samples presented a pure perovskite structure. The optimum density was noted for the sintering temperature of 1050 °C. The dielectric constant increased with an increasing sintering temperature and showed the maximum value of 885 at the sintering temperature of 1150°C.

Acknowledgments My advisor Prof. Dr. Gobwute Rujijanagul Electroceramics lab Member The 50th Anniversary Chiang Mai University Fund for Ph.D. Program

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