derek
New Member
Posts: 3
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Post by derek on Jul 28, 2018 22:54:53 GMT -5
Hi, I have been using VSM to measure the saturation magnetization(in emu/g) of thin film samples.There are some questions, though: my samples are ribbons (thickness is about 20 micrometers, width is about 1mm), in order to increase accuracy of sample mass measurement, I cut the ribbons into 8mm long pieces, then place them onto double-sided tape, side by side, then layer by layer(see attachment). Does this way of making samples affect the result? Also, the size(area) of the sample I made is about 8mm*4mm, what kind of sample holder should I use? Or should I reduce the sample size? Thanks a lot!  |
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Post by Lake Shore Cosmin on Jul 30, 2018 16:48:48 GMT -5
Hello Derek,
Thank you for contacting Lake Shore about your VSM measurement!
Amorphous wires and ribbons are indeed very light and measuring their mass surely poses a problem unless you have access to an analytical balance. I would still try to measure the mass precisely as much as possible but bundling together of few pieces of ribbon may work as well.
The VSM is calibrated using a 3 mm diameter Ni sphere. The moment reading is correct for a similar sample size and geometry. I think you should try to stack the ribbon in a ~3 mm cube sample. If you measure an elongated sample, but you calibrate with a sphere, you should align the sample with the field in order to minimize the errors. Even when doing this, having a dramatic different sample from calibrator, can introduce errors as high as 20% in the moment reading.
Since you already prepared the samples, try to glue it at the tip of the bottom-mount holder using GE varnish or superglue. Align the best you can the sample with the field direction and enlarge the EM gap to reduce the geometry mismatch effects.
To further eliminate the geometry and size effects, one can create a similar shape calibrator from pure Ni material, based on precise weight measurement. The pure Ni mass magnetization is 54.94 emu/g.
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derek
New Member
Posts: 3
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Post by derek on Jul 30, 2018 21:04:44 GMT -5
Hello Derek, Thank you for contacting Lake Shore about your VSM measurement! Amorphous wires and ribbons are indeed very light and measuring their mass surely poses a problem unless you have access to an analytical balance. I would still try to measure the mass precisely as much as possible but bundling together of few pieces of ribbon may work as well. The VSM is calibrated using a 3 mm diameter Ni sphere. The moment reading is correct for a similar sample size and geometry. I think you should try to stack the ribbon in a ~3 mm cube sample. If you measure an elongated sample, but you calibrate with a sphere, you should align the sample with the field in order to minimize the errors. Even when doing this, having a dramatic different sample from calibrator, can introduce errors as high as 20% in the moment reading. Since you already prepared the samples, try to glue it at the tip of the bottom-mount holder using GE varnish or superglue. Align the best you can the sample with the field direction and enlarge the EM gap to reduce the geometry mismatch effects. To further eliminate the geometry and size effects, one can create a similar shape calibrator from pure Ni material, based on precise weight measurement. The pure Ni mass magnetization is 54.94 emu/g. That's very helpful! Thank you very much! |
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derek
New Member
Posts: 3
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Post by derek on Jul 31, 2018 6:59:12 GMT -5
I got my result back today. The saturation magnetization is much lower (about 10~20 emu/g lower) than its normal value. I noticed that the sample holder my department used looks like 730933 Kel-F (side-mount). So I guess the magnetic field is in a transverse direction? Is this the reason for the low value? Or will the multiple layers of double-sided tape affect the result? Or maybe the instrument was not calibrated correctly?
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Post by Lake Shore Cosmin on Aug 1, 2018 8:14:19 GMT -5
Hello Derek,
The measurement geometry can influence the quantitative results significantly, as explained before. The side mount holder is not the best choice because the sample you have can't be oriented along the applied field. The double side tape and bundling the several strips together are not going to worsen the results. The VSM was calibrated with a sphere and you measure a much larger and very different geometry sample; therefore we can say that for your particular measurement, it would have been better to first calibrate the VSM with a similar shape and size sample. Please see my comments in the previous post.
The general conclusion I would like you to remain with is that the sample under test should be close in shape and dimensions to the calibration sample, otherwise the results may not be quantitatively correct.
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Post by swarna on Feb 27, 2019 21:37:51 GMT -5
Hi, I would like to order VSM 8604 series with Oven Model 86 and 86 VTA but I am still confuse about sample holders and sample rods, Are they included?
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Post by Lake Shore Cosmin on Mar 1, 2019 17:13:39 GMT -5
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