120CR0391_Abhisek Das_Seminar and Technical Writing .pptx

This is my seminar and technical writing on Piezoceramic.

1. Seminar And Technical Writing on “Piezoelectric Ceramics Or Piezoceramics” Presented to— Presented by- Prof.Debasish Sarkar Abhisek Das 120CR0391

2. Outline-> 1.Introduction 2.Fabrication 3.Processing 4.Types 5.Applications 6 .Advantages & Disadvantages 7.Conclusion 8.Reference

3. Introduction What is piezoelectric ? Pizo or piezein > squeeze or press and electron > amber, an ancient source of electric charge . » Piezoelectricity is a concept of conversion of mechanical energy to electrical energy and viceversa, not by any electromagnetic principle but by the process of Polarization . » Piezo-electricity, or pressure electricity, is defined as polarization induced by the application of external force.

4. Piezoelectricity is the ability of some materials to generate an electric charge in response to applied mechanical Stress. The piezoelectric effect is reversible. Direct piezoelectric effect: charge separation due to stress. converse piezoelectric effect: occurence of stress and strain when electric field is applied. Happens in insulating materials, Insulating Ferroelectric materials with a permanent dipole, In crystals(only crystals without symmetry centre ) .

5. The microscopic origin of the piezoelectric effect is the displacement of ionic charges within a crystal structure. In the absence of external strain, the charge distribution is symmetric and the net electric dipole moment is zero. However when an external stress is applied, the charges are displaced and the charge distribution is no longer symmetric and a net polarization is created. In order to create a net piezoelectric effect, the material must be: a . a pure crystal (difficult to realize in most cases ) b . the crystal domains must be brought into alignment during poling .

6. Operational Limits Of piezoelectric Materials During normal operation, a piezoelectric material is either strained ( to create an electric potential) or is subjected to an electric potential ( to create a strain). However, care must be taken to operate the material within the parameters specified by the manufacturer. Electrical depolarization can occur if a piezoelectric material is subjected to extreme electric fields (or voltages) which will cause it to lose (or significantly degrade) its piezoelectric effects. Mechanical depolarization can occur if a material is excessively strained to the point where the crystal domains are significantly disturbed . Thermal depolarization can occur if a material subjected to temperatures beyond the *Curie point” of the material.

7. How are Piezoelectric ceramics made ? Fine powders of the component metal oxides are mixed in specific proportions, then heated to form a uniform powder. The powder is mixed with an organic binder and is formed into structural elements. The elements are fired according to a specific time and temperature program, during which the powder particles sinter and the material attains a dense crystalline structure. The elements are cooled, then shaped or trimmed to specifications. Electrodes are applied to a conducting material, which is connected to the elements.

8. Crystal Structure and Dipole Moments A traditional piezoelectric ceramic is a mass of perovskite crystals. Each crystal consists of a small tetravalent metal ion, usually titanium or zirconium, in a lattice of larger divalent metal ions, usually lead or barium, and 02~ ions. At temperatures below the Curie point, however, each crystal has tetragonal or rhombohedral symmetry and a dipole moment. Above the Curie point each perovskite crystal in the fired ceramic element exhibits a cubic symmetry with no dipole moment.

9. Processing of Piezoelectric Ceramic

10. Types of Piezoelectric Materials 1. Naturally occurring crystals: Berlinite ( AIPO4), cane sugar, Quartz, Rochelle salt, Topaz, Tourmaline Group Minerals, and dry bone (apatite crystals) 2. Man-made crystals: Gallium orthophosphate ( GaPO4), Langasite (La3Ga5Si014) 3. Man-made ceramics: Barium titanate ( BaTiO3), Lead titanate (PbTiO3 ),Lead zirconate titanate - more commonly known as PZT, Potassium niobate (KNbO3 ), Lithium niobate (LiNbO3), Lithium tantalate ( LiTaO3) 4. Polymers: Polyvinylidene fluoride (PVDF )

11. Impact of Piezoelectric Materials

12. Applications of Piezoelectric ceramics The principle is adapted to piezoelectric motors, sound or ultrasound generating devices, and many other products. Generator action is used in fuel-igniting devices, solid state batteries, and other products. Motor action is adapted to piezoelectric motors, sound or ultrasound generating devices , and many other products. Generators Sensors Actuators Transducers . Transducers : convert mechanical energy into electrical energy (or vice versa) e.g . Mechanical to electrical: record player, strain gauge. cigarette lighter. e.g . Electrical to mechanical: production of ultrasonic waves.

13. Implementation Of Piezoelectricity In Practical life Energy Harvesting: Vibrations from industrial machinery can also be harvested by piezoelectric materials to charge batteries for backup supplies or to power low-power microprocessors and wireless radios. Piezoelectric elements are also used in the detection and generation of sonar waves. Inkjet printers: On many inkjet printers, piezoelectric crystals are used to drive the ejection of ink from the inkjet print head towards the paper. Diesel engines: High-performance common rail diesel engines use piezoelectric fuel. injectors, first developed by Robert Bosch GmbH, instead of the more common solenoid valve devices.

14. Piezoelectric motors: Piezoelectric elements apply a directional force to an axle , causing it to rotate. Due to the extremely small distances involved, the piezo motor is viewed as a high-precision replacement for the stepper motor. A recent application of piezoelectric ultrasound sources is piezoelectric surgery also known as piezosurgery.Piezosurgery is a minimally invasive technique that aims to cut a target tissue with little damage to neighboring tissues. It has the ability to cut mineralized tissue without cutting neurovascular tissue and other soft tissue, thereby maintaining a blood-free operating area, better visibility and greater precision. Ultrasonic piezo-sensors are used in the detection of acoustic emissions in acoustic emission testing .

15. Advantages & Disadvantages

16. Conclusion Piezoelectricity is a revolutionary source for “ GREEN ENERGY” . Flexible piezoelectric materials are attractive for power harvesting applications because of their ability to withstand large amounts of strain. Convert the ambient vibration energy surrounding them into electrical energy. Electrical energy can then be used to power other devices or stored for later use.

17. References "Introduction to Ceramics" by W.D. Kingery, H.K. Bowen, and D.R. Uhlmann. "Piezoelectric Ceramics" by A. Safari and S. Safari. Fundamentals of Piezoelectric Sensorics: Mechanical, Dielectric, and Thermodynamical Properties of Piezoelectric Materials" by B. Jaffe, W. R. Cook, and H. Jaffe. (Journal of the Acoustical Society of America ). "Review of the piezoelectric properties of ceramics with perovskite structures" by A.S. Bhalla, L.E. Cross, and R. Roy. (Journal of the American Ceramic Society ).

18. THANK YOU!!