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nanotube_growth [2013/04/16 17:49]
heather [Using the RGA]
nanotube_growth [2013/04/16 19:22] (current)
heather [Standard Operating Procedure]
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   *Go to the //Graphs tab// to view the current status of your gas flow rates, time remaining per stage, and internal pressure.   *Go to the //Graphs tab// to view the current status of your gas flow rates, time remaining per stage, and internal pressure.
   *At the end of your program, click the large //Stop// button. The Argon safety gas //should// begin to flow until the furnace temperature reaches 200C. Stage 5 in the recipe above is entered to ensure that the Argon gas does flow during cool down.   *At the end of your program, click the large //Stop// button. The Argon safety gas //should// begin to flow until the furnace temperature reaches 200C. Stage 5 in the recipe above is entered to ensure that the Argon gas does flow during cool down.
-*If you are modifying or using a different growth recipe, please read the following notes: + 
-    *Do not enter more than one stage in a row with temperatures below 100C. The furnace tends to overshoot the temperature,​ and the program will not proceed to the next stage within a reasonable amount of time (temperature will be too high, cool down is slow).+  ​*__If you are modifying ​the recipe above, ​or using a different growth recipe, please read the following notes:__ 
 +    ***Important:​ **You must purge the tube at low temperature (less than 200C) for at least 25 minutes at a total flow rate of about 2 SLM prior to a growth.  
 +      * The duration of the purge is not typically a concern in the 1" furnace because the 1" quartz tube is only about 0.5 L in volume. At a flow rate of 1 SLM, the entire gas content of the 1" tube is cleared every 30 seconds. The 4" tube, however, has a volume of approximately 12 L. At a flow rate of 2 SLM, the volume is cleared only //once every 6 minutes//. Excess oxygen with hydrogen, methane, and/or ethylene at high temperatures can result in an explosion.  ​ 
 +    *Do not enter more than one stage in a row with temperatures below 100C. The furnace tends to overshoot the temperature,​ and the program will not proceed to the next stage within a reasonable amount of time (temperature will be too high, cool down is slow). ​
     *For atmospheric pressure growths: In the stage after the final stage of your desired furnace program, select Argon for CNT or Graphene as appropriate,​ and enter a 1.9 SLM flow rate. Set temperature here to 200C, and enter 1 minute for the Duration. This is to protect your sample while the furnace is cooling down. (There is presently a bug in the program, the safety gas does not always automatically flow while cooling down.)     *For atmospheric pressure growths: In the stage after the final stage of your desired furnace program, select Argon for CNT or Graphene as appropriate,​ and enter a 1.9 SLM flow rate. Set temperature here to 200C, and enter 1 minute for the Duration. This is to protect your sample while the furnace is cooling down. (There is presently a bug in the program, the safety gas does not always automatically flow while cooling down.)
     *The gases in the first stage will begin flowing after the entered temperature has been reached. In the subsequent stages, the gases of the next stage will begin to flow as soon as the previous stage is complete (before the next temperature is reached). ​     *The gases in the first stage will begin flowing after the entered temperature has been reached. In the subsequent stages, the gases of the next stage will begin to flow as soon as the previous stage is complete (before the next temperature is reached). ​
 +    *Anytime you attempt a new recipe, you should babysit the furnace to make sure that the program proceeds the way you expect it to. The furnace program has a few bugs.
 ==== Leak checking ==== ==== Leak checking ====
 Leak checking is suggested every time the growth tubes are switched. Leaks during growth can result in bad yeilds and low growth, or, in a worst case scenario, an [[http://​www.science.oregonstate.edu/​~minote/​wiki/​doku.php?​id=4inSafety#​combustion_during_normal_operation|explosion]]. Leak checking is suggested every time the growth tubes are switched. Leaks during growth can result in bad yeilds and low growth, or, in a worst case scenario, an [[http://​www.science.oregonstate.edu/​~minote/​wiki/​doku.php?​id=4inSafety#​combustion_during_normal_operation|explosion]].

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