I know it is superconductive because it has a Meissner Effect. It is possible to estimate critical fields and determine J in the order of 108 A/cm2 ? Does the attached article help me?
Yes. Simply, you may use equation (4) from this article to calculate the critical current density from the magnetization hysteresis loop.
You need to determine the width of the hysteresis loop 'delM' and then based on the dimensions of the sample used for magnetisation measurement, you need to compute 'd'. Then Jc can be computed as follows: Jc = 20 DelM /d where d = b[1-(b/3a)], Here a and b are dimensions of the sample used for measurement.
what are a, b of sample. Most people write they are sample dimensions
what is the basic equation of Bean Model use for jc measurement from MH loop?
Dear all. Kindly, explain, what should be the units of del M and a, b be used to obtain the units of A/cm2
Dear Dr Muhammad Waqee Ur Rehman,
to obtain Jc in A/cm^2 from Jc = 20 Delta M / {b[1-(b/3a)]} , Delta M should be in emu/cm^3 or Gs and a, b should be in cm.
thank you sir Denis Gokhfeld . But I have del m in emu/g, what I should do?
thanks in advance
multiply del m on the physical density of the sample or m/V in g/cm^3
Dear Ujjal Lamichhane,
we use Bean critical current model because we can't directly measure this value. According to this model a and b are the dimensions of the sample, for rectangular shape. It's meaningful that cutting the bulk sample to rectangular if you have other shapes. Because edges of the sample should be straight to obtain homogenius magnetic flux lines. By the way Bean critical state model can be apply to thin film as following equation:
Jc = 30 Delta M / R where R is the equivalent radius of the sample.
If sample is in powder form and put that sample inside a cylindrical capsule can we use Jc = 30 Delta M / R formula?? Thanks in advance
Ujjal Lamichhane Generally, M-H loop measurements are in terms of emu. If you divide emu into cm^3 you can get volume magnetization. emu/cm^3 equals to 10^3 A/m and it should be converted to A/cm by divided 10^2. Finally you have only 10 constant. However, M-H loop have two different part which one of them is M+ and the other is M-. That is why 10 constant should be multiply with 2. Now you have 20...
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