<< Chapter < Page Chapter >> Page >
Section 4.3 describes the Dielectric Loss and Loss Angle.Section 4.4 describes the piezoelectric material and Quartz CrystaL Oscillator.

Section 4.3. Dielectric Loss.

Theoretically the dielectric constant is real and a capacitor having a dielectric separation of plates always causes a 90° Leading Current with respect to the applied voltage hence loss is zero and an ideal capacitor is always a conservative system. But as we have seen that dissipative absorption can take place at higher frequencies. The relative permittivity at alternating frequency is lower than DC relative permittivity and relative permittivity becomes complex at frequencies where loss occurs.

Thermal agitation tries to randomize the dipole orientations whereas the applied alternating field tries to align the dipole moment along the alternating field. In process of this alignment there is inevitable loss of electric energy. This loss is known as Dielectric Loss. The absorption of electrical energy by a dielectric material subjected to alternating Electric Field is termed as Dielectric Loss.

The real part is the Relative Permittivity and the imaginary part is the Energy Loss part. Because of Complex Relative Permittivity a loss angle (δ) is introduced.

4.3.1. Loss Angle (δ).

Parallel plate capacitor is given as follows:

To account for the lossy nature of the dielectric we assume complex relative permittivity. Hence we get:

Real part of the Capacitance causes Quadrature Component and Imaginary Part causes In-Phase component. The In-phase component causes the loss angle hence loss angle is defined as:

In the Table 4.3.1.we tabulate some important dielectrics and their loss Tangents. In Figure 4.4 the Relative Permittivity Real Part and Imaginary Part is plotted as frequency.

Table 4.3.1. Some important dielectrics and their loss angle tangent.

Ceramics Tan (δ) Dielectric Strength Applications
Air 0 31.7kV/cm at 60 Hz Tested in 1cm gap
Al 2 O 3 0.002 to 0.01
SiO 2 0.00038 10MV/cm at DC IC Technology MOSFET
BaTiO 3 0.0001 to 0.02
Mica 0.0016
Polystrene 0.0001 Low loss Capacitance
Polypropylene 0.0002 Low loss Capacitance
SF 6 Gas 79.3kV/cm at 60 Hz Used in High Voltage Circuit BreaakersTo avoid discharge
Polybutane >138kV/cm at 60 Hz Liquid dielectric in cable filler
Transformar Oil 128kV/cm at 60 Hz
Borosilacate Glass 10MV/cm duration 10μs6MV/cm duration 30s

As seen in Figure 4.4, there is significant loss at low frequency, at Radio-Wave frequency, at Infra-Red frequency and at Ultra-Violet frequency. These correspond to the natural frequencies of the electron cloud system shown in Figure 4.3. For High-Q systems we require capacitance with dielectric material having a very low loss angle. These are generally Poly-sterene Capacitances or Poly-propylene Capacitors.

Section 4.4. Piezoelectric Effect and Piezoelectric Materials.

Electricity resulting from Pressure is known as piezo-electricity. This is called piezo-electric effect.

Electricity causes deformation of such materials. This is known as inverse piezo-electric effect. The most commonly used piezo-electric materials are Quartz, Rochelle Salts, Sodium Potassium Tartarate and tourmaline.

Rochelle Salts are mechanically weak but electrically very sensitive. Hence used in micro-phones, heads-phones and loud speakers.

Tourmaline are mechanically the strongest but electrically least sensitive. At frequencies higher than 100MHz, vibrational breakage can take place hence mechanically strongest materials are used namely Tourmaline.

Quartz Wafers are very popular as the stab lest electronic oscillators. These are known as Quartz Crystal Oscillators and to date these are stab lest with only 1part in million drift due to temperature, aging or load. Recently MEMS oscillators have proved to be even more stable. In Quartz Crystal Oscillators, Quartz mechanically oscillates but because of its piezo-electric property it behaves like a LC Tank-circuit with a very high Q Factor. Hence it allows the electronic oscillator to oscillate at its Resonance Frequencies which are critically dependent on the Physical Dimensions. Hence as long as Physical Dimensions are accurately reproduced so long the requisite Oscillation Frequency is accurately generated. The resonance frequencies of some of the standard cut Quartz Wafers are given in Table 4.4.1.

Table 4.4.1. Resonance frequencies and the Q-Factor of standard cut Quartz Wafers.

Frequecy(Hz) 32k 280k 525k 2M 10M
R S (Ω) 40k 1820 1400 82 5
L S (H) 4800 25.9 12.7 0.52 12mH
C s (pF) 0.0491 0.0126 0.00724 0.0122 0.0145
C p (pF) 2.85 5.62 3.44 4.27 4.35
Q Factor 25,000 25,000 30,000 80,000 150,000

The electrical analog of the mechanical vibration of Quartz Crystal is as follows:

Electrical Analog of the Mass of the Quartz Wafer is L S .

Electrical Analog of the spring constant of the Quartz Wafer is C S .

Electrical Analog of the damping of the Quartz Wafer is R S .

C P is the parallel electrode capacitance.

L S , C S , R S comprises the intrinsic series resonance path and C P is in parallel with this Series Resonance Path as shown in Figure 4.5.

Questions & Answers

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Electrical and electronic materials science. OpenStax CNX. May 01, 2014 Download for free at http://cnx.org/content/col11615/1.14
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Electrical and electronic materials science' conversation and receive update notifications?