Planetary Ball Milling - Revision history

W.rheinheimer: /* Sieving */

2021-07-19T13:24:09Z

‎Sieving

2021-07-19T13:23:54Z

‎Sieving

2021-06-10T11:17:01Z

2021-06-10T10:45:16Z

‎Separating the slurry

2021-06-10T10:43:35Z

‎Separating the slurry

2021-06-10T10:41:33Z

‎Filling the milling jars

2021-06-10T10:39:19Z

‎Sieving

2021-06-10T10:34:01Z

‎Milling procedure

2021-06-10T10:33:44Z

‎Milling procedure

2021-06-10T10:31:07Z

‎Filling the milling jars

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 Drying usually takes at least one day.
 == Sieving ==
-As after drying, the powder is usually agglomerated, it should be sieved on a
+As after drying, the powder is usually agglomerated, it should be sieved on a [[Vibrating sieve]] once it is completely dry. Avoid sieving slightly humid powder. Remember that sieves are one of the major sources of contamination so that a separate sieve should be selected for each material.
 Select a clean sieve with about 50µm mesh size, put in on a suitable pan with sealing and a clean sieve top. Add about 50 1cm-sized zirconia balls and put the setup on a vibrating sieve. Select the amplitude sich taht the milling balls jump on the sieve, but do not hit the top plate frequently. While more and more powder passes the sieve, the amplitude needs to be reduced. Wait until most of the powder has passed the sieve.
 The last remainings in the sieve can be discarded as the sieve is meant to remove large particles in the powder, but remember that this might change your overall stoichiometry.

@@ Line 52: / Line 52: @@
 Drying usually takes at least one day.
 == Sieving ==
-As after drying, the powder is usually agglomerated, it should be sieved once it is completely dry. Avoid sieving slightly humid powder. Remember that sieves are one of the major sources of contamination so that a separate sieve should be selected for each material.
+As after drying, the powder is usually agglomerated, it should be sieved on a
 Select a clean sieve with about 50µm mesh size, put in on a suitable pan with sealing and a clean sieve top. Add about 50 1cm-sized zirconia balls and put the setup on a vibrating sieve. Select the amplitude sich taht the milling balls jump on the sieve, but do not hit the top plate frequently. While more and more powder passes the sieve, the amplitude needs to be reduced. Wait until most of the powder has passed the sieve.
 The last remainings in the sieve can be discarded as the sieve is meant to remove large particles in the powder, but remember that this might change your overall stoichiometry.

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 Rember to stir the mix of powder with a glas rod, balls and liquid until no air bubbles are hidden somewhere in the mix of balls, powder and liquid. Otherwise you will not be able to judge the viscosity.
 [[File:20210520 102316.jpg|thumb|center]]
 == Milling procedure ==

← Older revision		Revision as of 10:45, 10 June 2021
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	After emptying the milling jar, it is worth to check if there is some powder sticking to the bottom of the jar, which might indicate an incomplete milling and mixing due to an air bubble on the bottom of the jar. This will potentially result in a change in stoichiometry of the powder and can be prevented by initial mixing by stiring after filling the jar and before the milling cycle.		After emptying the milling jar, it is worth to check if there is some powder sticking to the bottom of the jar, which might indicate an incomplete milling and mixing due to an air bubble on the bottom of the jar. This will potentially result in a change in stoichiometry of the powder and can be prevented by initial mixing by stiring after filling the jar and before the milling cycle.
		+
		+	If the weight loss of the jar is measured by weighting the dry and unfilled jar and top plate before and after milling, an approximation for the abraision during milling can be obtained. For larger milling balls (where no balls are lost during the entire procedure inc. cleaning), the weight loss can also be measured.

	[[File:20210520 180037.jpg\|thumb\|center]]		[[File:20210520 180037.jpg\|thumb\|center]]

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 == Separating the slurry ==
 Use a very clean sieve (sieves are a source of contamination) and a wide and clean glass beaker to separate the slurry and balls. The finer the balls are, the more slurry and powder remains in the balls. To a ceratin amount, it can be drained with additional liquid.
 If the balls are smaller than 2mm, it is best to use a technical sieve with 150µm mesh. Using a funnel and a glas bottle with vacuum adapter all with appropriate sealing will ease the procedure and minimize the amount of solvent needed to separate the slurry.
 [[File:20210520 180037.jpg|thumb|center]]
 == Drying ==
 The glass beaker is covered with aluminium foil with a number (10-30) holes to allow evaporation of the liquid. The beaker then can be dried in a laboratory oven at a temperature below the boiling temperature of the liquid. Boiling should be prevented as it can cause contamination of the oven.

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 The milling jars are filled with balls and powder and liquid sucht that the overall filling reaches 2/3 of the volume of the jar. A bit less is possible, while more is not.
 A good weight ratio of milling balls to powder is 8:1 for the perovskite SrTiO3. The amount of liquid added to the milling media should be chosen such the slurry is not highly viscous. For SrTiO3, this is about 200ml on 800g balls and 100g powder.
 Rember to stir the mix of powder with a glas rod, balls and liquid until no air bubbles are hidden somewhere in the mix of balls, powder and liquid. Otherwise you will not be able to judge the viscosity.

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 == Milling procedure ==
 The design of the milling run itself is mill-specific. ON the PM400 by Retsch, the following setup and program gives a very fine (well below 1µm) milling result:
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 * Milling cycle: 5mins milling, 25mins break to prevent overheating
 * 15 cycles
 == Separating the slurry ==