Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!decwrl!pa.dec.com!tethys.ph.albany.edu!tivol From: tivol@tethys.ph.albany.edu Message-ID: <009866F0.5E3D9CA0.11600@tethys.ph.albany.edu> Subject: SEM of powder slurries Date: Mon, 24 Oct 1994 17:51:41 EDT X-Received: by usenet.pa.dec.com; id AA29100; Mon, 24 Oct 94 15:30:28 -0700 X-Received: by pobox1.pa.dec.com; id AA05179; Mon, 24 Oct 94 15:30:22 -0700 X-Received: from mse.engin.umich.edu by inet-gw-3.pa.dec.com (5.65/10Aug94) id AA22678; Mon, 24 Oct 94 15:27:29 -0700 X-Received: by mse.engin.umich.edu with SMTP;24 Oct 1994 18:24:49 U X-To: microscopy@aaem.amc.anl.gov Lines: 24 Dear Robin, I have just started to look at clay mineral particles on the HVEM, a TEM rather than an SEM. The colleague investigating clay from the bottom of the Hudson river collects a sample of the sediment, washes it and settles it. During the settling, she collects fractions at various times; these are label- led for their nominal sizes-- >5mu, 2mu, <2mu and <<2mu. I had difficulties getting good dispersal on a carbon-coated mesh grid at first, but I found that if I put a drop of poly-l-lysine on the grid and let it dry, I could then agi- tate the suspension of clay particles and put a 5 mu-liter drop on the grid. This gave me very good dispersion of both the largest and the smallest parti- cles. I must emphasize that this is my first venture with anything like this, so listen to the real experts if any respond. (I forgot to say that the 5 mu- liter drop I put on the grid was just air dried.) I am aware that clay mine- rals' structures change when they dry, but we wanted to try the simplest thing first. Good luck. Yours, Bill Tivol ========================================================================== Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!olivea!decwrl!pa.dec.com!imatge.sct.ub.es!yves From: yves@imatge.sct.ub.es ("Yves Maniette") Message-ID: <1275.yves@imatge.sct.ub.es_POPMail/PC_3.2.2> Subject: Re: SEM of powder slurries Date: Tue, 25 Oct 94 13:26:43 CST X-Received: by usenet.pa.dec.com; id AA12916; Tue, 25 Oct 94 05:30:49 -0700 X-Received: by pobox1.pa.dec.com; id AA12254; Tue, 25 Oct 94 05:30:40 -0700 X-Received: from mse.engin.umich.edu by inet-gw-3.pa.dec.com (5.65/10Aug94) id AA21737; Tue, 25 Oct 94 05:25:55 -0700 X-Received: by mse.engin.umich.edu with SMTP;25 Oct 1994 08:23:51 U X-Popmail-Charset: Spanish X-To: microscopy@aaem.amc.anl.gov Lines: 61 For Robin Griffin On Mon, 24 Oct 94 14:12:00 CDT, Griffin, Robin wrote: > >Help! > >We would like to characterize ceramic powders that are in an aqueous >solution. We need to know if the powders are individual powders or >agglomerates. Does anyone have any suggestion on SEM sample prep? Is >there a drying technique that leaves the particles well dispersed? > >Also, what is the typical TEM sample prep techniques used for ceramic >powders? I usually use the following technique for preparing powder samples for TEM. It could however be used also for SEM preparation. 1. Put the powder sample in a small becher with ethanol, in rather high concentration. 2. prepare another small becher (20 cc) filled with clean distilled water, nearly overful. You should get the feeling that adding one more drop of water would get it overflow... The best is to have a cylindrical becher, without the pouring part. 3. manage in order to have the reflexion of a white fluorescent tube light on the surface of the water. This will help you later in seeing where the particles are on the surface of the water. 4. drop one tiny drop of your ethanol suspension on the water. The drop will expand on the water surface, and you will get a film of sample on the surface. 5. Have a TEM grid with carbon film prepared, take it with tweezers, get it touch the water surface, wher the sample is (here you need a good eye, and the fluorescent tube dicussed above). When removing the grid, orient it at 45 degrees, so that only a small drop of water gets stuck to it, on one edge. allow then this drop of water to touch a filter paper. The water will be thus removed instantaneously, and nearly no further drying will be be necessary. Hence pollution problems will be avoided. The sample particles stuck on the film won't get away with the water. Note. Instead of the becher filled with ethanol, you may as well use an agata mortar. About the dispersion of particles, it might however be possible that it is changed depending on the solution. Surely water and ethanol do not behave the same way. If you have any further question, do not hesitate to get in touch with me directly. Yves MANIETTE UNIVERSITAT DE BARCELONA - SERVEIS CIENTIFICO TECNICS - UNITAT ESCA-TEM Carrer Lluis Sole i Sabaris, s/n - 08028 Barcelona Espana. Tel +34 3 402 1695 - Fax +34 3 339 3798 ========================================================================== Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!olivea!decwrl!pa.dec.com!imatge.sct.ub.es!yves From: yves@imatge.sct.ub.es ("Yves Maniette") Message-ID: <1275.yves@imatge.sct.ub.es_POPMail/PC_3.2.2> Subject: Re: SEM of powder slurries Date: Tue, 25 Oct 94 13:26:43 CST X-Received: by usenet.pa.dec.com; id AA12916; Tue, 25 Oct 94 05:30:49 -0700 X-Received: by pobox1.pa.dec.com; id AA12254; Tue, 25 Oct 94 05:30:40 -0700 X-Received: from mse.engin.umich.edu by inet-gw-3.pa.dec.com (5.65/10Aug94) id AA21737; Tue, 25 Oct 94 05:25:55 -0700 X-Received: by mse.engin.umich.edu with SMTP;25 Oct 1994 08:23:51 U X-Popmail-Charset: Spanish X-To: microscopy@aaem.amc.anl.gov Lines: 61 For Robin Griffin On Mon, 24 Oct 94 14:12:00 CDT, Griffin, Robin wrote: > >Help! > >We would like to characterize ceramic powders that are in an aqueous >solution. We need to know if the powders are individual powders or >agglomerates. Does anyone have any suggestion on SEM sample prep? Is >there a drying technique that leaves the particles well dispersed? > >Also, what is the typical TEM sample prep techniques used for ceramic >powders? I usually use the following technique for preparing powder samples for TEM. It could however be used also for SEM preparation. 1. Put the powder sample in a small becher with ethanol, in rather high concentration. 2. prepare another small becher (20 cc) filled with clean distilled water, nearly overful. You should get the feeling that adding one more drop of water would get it overflow... The best is to have a cylindrical becher, without the pouring part. 3. manage in order to have the reflexion of a white fluorescent tube light on the surface of the water. This will help you later in seeing where the particles are on the surface of the water. 4. drop one tiny drop of your ethanol suspension on the water. The drop will expand on the water surface, and you will get a film of sample on the surface. 5. Have a TEM grid with carbon film prepared, take it with tweezers, get it touch the water surface, wher the sample is (here you need a good eye, and the fluorescent tube dicussed above). When removing the grid, orient it at 45 degrees, so that only a small drop of water gets stuck to it, on one edge. allow then this drop of water to touch a filter paper. The water will be thus removed instantaneously, and nearly no further drying will be be necessary. Hence pollution problems will be avoided. The sample particles stuck on the film won't get away with the water. Note. Instead of the becher filled with ethanol, you may as well use an agata mortar. About the dispersion of particles, it might however be possible that it is changed depending on the solution. Surely water and ethanol do not behave the same way. If you have any further question, do not hesitate to get in touch with me directly. Yves MANIETTE UNIVERSITAT DE BARCELONA - SERVEIS CIENTIFICO TECNICS - UNITAT ESCA-TEM Carrer Lluis Sole i Sabaris, s/n - 08028 Barcelona Espana. Tel +34 3 402 1695 - Fax +34 3 339 3798 ========================================================================== Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!decwrl!pa.dec.com!ml.wpafb.af.mil!WALCKSD From: WALCKSD@ml.wpafb.af.mil Message-ID: <9410251526.AA25717@riker.ml.wpafb.af.mil> Reply-To: WALCKSD@ml.wpafb.af.mil Subject: SEM of powder slurries Date: Tue, 25 OCT 94 11:25:10 EST X-Received: by usenet.pa.dec.com; id AA17247; Tue, 25 Oct 94 19:02:15 -0700 X-Received: by pobox1.pa.dec.com; id AA24618; Tue, 25 Oct 94 19:01:53 -0700 X-Received: from mse.engin.umich.edu by inet-gw-1.pa.dec.com (5.65/10Aug94) id AA11869; Tue, 25 Oct 94 18:56:24 -0700 X-Received: by mse.engin.umich.edu with SMTP;25 Oct 1994 21:50:51 U X-In-Reply-To: Message from {rgriffin@eng.uab.edu}:ddn:wpafb of 10-24-94 X-To: microscopy@aaem.amc.anl.gov, rgriffin@eng.uab.edu Lines: 63 Hi Robin, You should contact John Mansfield at Michigan. They have an Electroscan SEM that will allow you to look at the powders while in the aquaeous solution. I'm sure that he can set you straight on whether this might be an appopriate application. For drying, you might want to talk to some of the biological people there. If the problem is with surface tension bring the particles together when they dry, contact John Panitz at the Univ. of New Mexico. He has been licking the surface tension problem of putting biological molecules on the surfaces of metal tips for a number of years. He uses a fast freezing mechnaism that he designed for doing this. He presented a talk in New Orleans at MSA. I have also been doing some microtoming of powders for use as EDS standards. I tried using G1 epoxy (Epoxy Technology EpoTek 353ND) and doing it by routine dimpling and ion milling, but there was quite a bit of porosity in the epoxy after setting. There is a guy here that has done coated SiC fibers encapsulated in epoxy (G1) and used the tripod polisher. He has gotten some good results after ion milling at low angles. (You can get a special stub for the Duomill for low angle milling.) To use at 200 kV, I have to put a thin coat of carbon on the microtomed samples, but it doesn't seem to affect my k-factors. Of course if you are after the oxygen or other light elements, this would be a problem for you. At 100 kV, the resin used for microtoming is a lot more stable and you don't have to coat with carbon. Also, in the three MRS "How to" books on TEM sample preparation, there are several methods presented for powders. Call me if you have questions. Regards, Scott ---------------------- Replied Message Body ---------------------- Date: 10-24-94 4:40pm From: {rgriffin@eng.uab.edu}:ddn:wpafb To: WALCKSD:ml:wpafb, SCHELTFJ:ml:wpafb Subj: SEM of powder slurries Orig-Author: {"Griffin, Robin" }:ddn:wpafb ----------------------------------------------------------- Help! We would like to characterize ceramic powders that are in an aqueous solution. We need to know if the powders are individual powders or agglomerates. Does anyone have any suggestion on SEM sample prep? Is there a drying technique that leaves the particles well dispersed? Also, what is the typical TEM sample prep techniques used for ceramic powders? ========================================================================== Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!decwrl!pa.dec.com!ttown.apci.com!stetsjr From: stetsjr@ttown.apci.com (James R. Stets) Message-ID: <9410251309.AA27854@ttown.apci.com> Subject: Re: TEM/SEM of powders Date: Tue, 25 Oct 94 09:09:11 -0400 X-Received: by usenet.pa.dec.com; id AA13607; Tue, 25 Oct 94 06:30:25 -0700 X-Received: by pobox1.pa.dec.com; id AA12777; Tue, 25 Oct 94 06:30:20 -0700 X-Received: from mse.engin.umich.edu by inet-gw-3.pa.dec.com (5.65/10Aug94) id AA26370; Tue, 25 Oct 94 06:28:57 -0700 X-Received: by mse.engin.umich.edu with SMTP;25 Oct 1994 09:27:45 U X-To: microscopy@aaem.amc.anl.gov Lines: 27 In response to R. Griffin's inquiry about sample prep for powders: A powder in aqueous solution can be added dropwise to a culture tube containing methanol. The culture tube is in a rack inside an ultra- sonic bath to disperse the particles. After a minute or two, the solution can be dropped on to an SEM stub or a TEM grid using an eye dropper or capillary tube open at both ends. I like to use a polished SEM stub because it has a smooth surface and makes it easier to see the particles. If you are using a TEM grid, place the grid on top of 2 sheets of lens tissue before dropping the dispersion on to the grid; this will quickly wick away the solvent and keep the particles reasonably dispersed. You can try other solvents (like hexane) but they may not be compatible with water (the particles tend to flocculate). Methanol or Ethanol usually work better in an aqueous solution. The main idea is to disperse the partcles ultrasonically, then use a volatile solvent which will evaporate quickly before the particles have a chance to re-agglomerate. Jim Stets Air Products and Chemicals, Inc. Allentown, PA stetsjr@ttown.apci.com ========================================================================== Newsgroups: sci.techniques.microscopy Path: dartvax.dartmouth.edu!news.bu.edu!olivea!decwrl!pa.dec.com!mcmail.cis.mcmaster.ca!hudakjm From: hudakjm@mcmail.cis.mcmaster.ca (John M Hudak) Subject: SEM of powder slurries. Message-ID: Date: Tue, 25 Oct 1994 14:51:06 +0059 (EDT) X-Received: by usenet.pa.dec.com; id AA16082; Tue, 25 Oct 94 18:32:42 -0700 X-Received: by pobox1.pa.dec.com; id AA24338; Tue, 25 Oct 94 18:32:18 -0700 X-Received: from mse.engin.umich.edu by inet-gw-1.pa.dec.com (5.65/10Aug94) id AA10541; Tue, 25 Oct 94 18:29:37 -0700 X-Received: by mse.engin.umich.edu with SMTP;25 Oct 1994 21:26:13 U X-To: microscopy@aaem.amc.anl.gov X-Mime-Version: 1.0 X-Content-Type: TEXT/PLAIN; charset=US-ASCII Lines: 27 We quite frequently have to do SEM of many different kinds of powders. The problem with putting a drop of suspended particles on a stub is that surface tension draws the particles into clumps as the liquid dries. This is the technique that I use: 1. Make a very dilute suspension of the particles in methanol. You may have to determine the concentration by trial and error but it is very low. 2. Set up a vacuum filtration system using 10mm dia. Nuclepore filter membranes. I use filters with a pore size of 0.1um. 3. Vacuum filter a few drops of the suspension through the membrane. 4. Mount the filter on a stub and coat. By vacuum filtering, the liquid leaves the particles almost immediately so that surface tension doesn't have a chance to form clumps. Nuclepore is the best filter to use because it is a sieve with small holes on a flat background which makes it easier to see the particles. ____________________________________________________________________ John Hudak hudakjm@mcmaster.ca I.M.R. - Electron Optics McMaster University, Hamilton, Ontario, Canada