Piezoelectric ceramics based on lead-free Na0.5Bi0.5TiO3

At the EU Council of Ministers (EU) on 7 June 2002 in Luxembourg, adopted important directives on Waste Electrical and Electronic Equipment (EEE) and limiting the use of certain hazardous substances:

• Directive 2002/96/EC of the European Parliament and of the Council of 27 January 2003 on waste electrical and electronic equipment (WEEE)
• Directive 2002/95/EC of the European Parliament and of the Council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS)
According to the directives of standards RoHS (Restriction of Hazardous Substances) and WEEE, since July 1, 2006, all EEE should be made in compliance with stringent environmental standards and does not contain chemical elements such as lead, mercury, cadmium and other hazardous compounds.

Basic material for the piezoelectric elements is a ceramic based on oxides of zirconium, lead, and titanium (PZT). Piezoelectric Ceramics PZT system is widely used:
a) The sensors in the measuring technique.
b) The generators and receivers of ultrasonic flaw detectors for different purposes (industry, transport, medicine).
a) Technology: cleaning fluids, emulsifying, dispersing, etc.
d) Security devices and burglar alarm.
e) Domestic appliances: the lighter elements of washing machines and dishwasher, toys.
e) MEMS - microelectromechanical systems.
Although all types of piezoceramic PZT is the best and satisfies the various requirements, ceramic PZT has several disadvantages:
1. Difficulties in manufacturing technology related to the evaporation of lead.
2. High levels of lead, increases the cost of production pottery at the expense of serious security operators.
3. Environmental pollution by lead in the manufacture of piezoelectric elements.

There are many other types of piezoelectric ceramics, which are inferior parameters of PZT. Therefore the development of new high piezomaterial does not contain lead-based alloys Na0.5Bi0.5TiO3, satisfying the basic requirements of applications is important for the development of world industry. The base of the piezoelectric ceramics has d33 = 250 pK / N and electromechanical coupling coefficient k33 = 90% (the maximum of the known piezoelectric materials). Using a variety of alloying elements may increase the piezoelectric constant d33 of 450 pK / N. When hot pressing technology becomes transparent material with high electro-optic coefficient. Due to the lack of lead production piezoceramics Na0.5Bi0.5TiO3 much cheaper than ceramic PZT.