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College of St. Rose, Albany ​my name is Tuesday Kuykendall and I am the scientific and struck technician for the material science engineering department at the University of Washington and this is our focus d8 x-ray diffractometer the Brooker d8 focus x-ray spectrometer is used to measure the crystal structure of powders or thin film materials the x-rays are produced in evacuated tube similar to a cathode ray tube an applied current heats up a tungsten filament which liberates electrons the liberated electrons are accelerated by a high voltage and hit a copper target where copper x-rays are generated the x-rays exit the tube and are incident on the sample from which they are diffracted into a scintillating type detector the beam passes through a slit which determines the angular width of the beam wider slits give more energy but have wider Peaks smaller slits give less energy but better resolution the beam also passes through a nickel filter the nickel filter removes the K beta energy before the diffracted beam enters the detector x-rays at angle theta are reflected from internal crystal planes separated by distance deep the Bragg diffraction results from constructive wave interference when the quantity 2 D sine theta is an integral number of wavelengths a fine powder material contains many crystals located at random angles certain crystals happen to be oriented so that the x-ray beam crystal and detector satisfy Bragg's equation this causes a signal spike at specific detector angles it is important to have a sufficient number of crystals to have an even distribution at all possible crystal orientations during the scan the detector is rotated over a range of angles to detect bands of diffracted x-rays produced by the correctly aligned crystals within the sample so now we're going to discuss sample preparation for x-ray diffractometer e powder diffraction it is important to have a well-defined polycrystalline material and the individual particle sizes of your material should be below 45 microns you need enough to fill one of these wells and it should be packed in and it's what is important is to have enough of each individual crystal it plane so that when the beam hits it at a particular angle Bragg's equation is satisfied and you get a peak this is sort of a statistics issue and so you want to make sure you have plenty of sample so that they are all those planes are represented there's two sizes of sample holders here this is preferred this large well here because as I said the more particles that you have represented on the surface in all the various crystal planes the better your data is going to be but often most people don't have this much material and this will work if your material has been prepared correctly it's just really important to make sure you have a very fine powder we have sample holders in here in the lab and once your sample has been prepared properly you're welcome to come in and use our sample holders but we ask that you please clean up after you're finished and that they should never leave the lab place your sample in the well and just kind of estimate how much you're going to need you're going to be pressing it down and you want to make sure that it's filling the well but it's still flat with the surface of the sample folder and you just gently scrape off whatever comes out of the well and you want to keep it cleaned up because keep in mind you're going to put this in and there's going to be three pins on three places on the sample holder and if there's a lot of material underneath there that's going to actually alter the angle that it's sitting at and you'll get your your positions will be off flatten it down and that's ready to go even though it's loose powder if you've prepared it correctly it will actually hold together on its own to verify that you have that just kind of tip it up at a 45 degree angle and make sure that it's holding the sample stage is held in place with a pressure plate the position of the beam is fixed and therefore the position in the z-axis must be very accurate the plane of the sample must be the same as the plane of the sample holder that is defined by three pins once your sample is loaded you can close the doors the doors are leaded-glass and our part of the safety circuit in the instrument so we are generating x-rays and those are radiation and could be dangerous radiation doesn't travel very far doesn't travel through six objects and it doesn't travel through lead so these are leaded glass and they have little pins in the handles that will engage mechanical switches in this right right in here in the door and then there's also electronic switches in the door in the bottom and the top what this does is ensures that when you close the door all the switches have engaged correctly and that the door is correctly closed if the door is not correctly closed it will cause the safety circuit to trip and it will shut everything down there's a control panel here and the exact same set of control panels over there and there's LED lights that ready on alarm and busy they're all important to note what state they're in these these buttons up here you must never touch the

only button that you ever want to push on this panel is this big green square button and that's the door open button to check to make sure you've done it properly just check down here and look and verify that the LED has gone off two of the mechanical things that are really important to watch for is how you open and close the door because that can trigger the safety circuit and also how you load and unload your sample the reason that we're concerned about the safety safety circuit is that inside our evacuated tube is our tungsten filament and this filament has a really high power across it and just like with a regular lightbulb if you over time that filament will become brittle and break and we want to take we want to extend that amount of time as much as possible and so when we we bring the current and voltage down or we bring the current and voltage up we're doing it slowly so that this this filament has a chance to soak and to slowly get up to power and this will help to extend its life time so now that we've looked at the the physical part of the instrument we're now going to go to the computer and this is where we do the controlling and where we control the ramp where we control the power to the tube this is XRD commander this application should always be on one of the reasons is that the XRD commander is what is controlling the x-ray diffractometer and it's also controlling the power this is where the power is changed by the user where it says set and you'll see that right now the black is 40 and 40 kilovolts and milliamps but the blue indicated here is the status that's the current status of the power at twenty kilovolts and five milliamps is standby status if x-ray commander is not open it will not go into this standby status and the tube will be at maximum power for too long and we want to extend the life of the tube as much as possible so we want to be able to allow it to go into standby mode it will do this automatically after 30 minutes of non-use when you do want to begin you want to ramp your power up to 40 and 40 kilovolts it's important not to just hit set right here you want to ramp it up slowly so what you want to do is input the values first and so we're going to ramp the kilovolts up by 10 kilovolts first leaving the current the same and then we're going to ramp up the current so I'm going to put in 30 millivolts and five milliamps and then press the set button now we want to wait approximately 30 seconds to a minute between each step to give it time to soak at that power it's been about 30 seconds so I'm going to go ahead and go to 40 kilovolts and 5 milliamps all right so it's been about 30 seconds and I'm going to go ahead and ramp this up to 20 so now let's go ahead up to 30 milliamps we can run a scan in this window very easily we just put in the start value then the x-axis here refers to the position of the detector and we call it to theta the start button here this is set already at 25 to that 85 to theta we have an increment here this is in values of 2 theta and it's set right now at 0.03 2 theta and then our scan speed the set setting here is 2 seconds per step if you want to do a standard scan that's similar to what you see in most of the literature you would have a start value of 10 an end of 90 your increment will be 0.02 and your time will be 1 second and that's a standard scan now the other thing to note it says shutter and x-ray the shutter is closed and it's green which indicates that you can open and close the door and the power to the x-ray is on there are buttons here open close on and off that you do not want to select if you start to select these manually there can be problems with the timing in the computer it's set up to do this automatically up here we have another place where you can actually change the positions of the detector and the sample right now the blue just like with the power the blue is the current status of the position and the block over here is where you want to change it to right now it's at 42 and 85 and I'm going to change it to 30 and 60 and then there's a little icon up here that says move drives just press that and the drives will move to that position this is not necessary to do to run your scan when you hit the start button it's just going to go to wherever value you have in here but it is convenient to be able to move the detector and the sample exchanger if it's at a weird angle to start with so if I run a scan from this window I can get a perfectly good scan I can run the standard or I can do a quick scan whatever I want however this data will not automatically be saved in order to automatically save data I need to set up a parameters file and then call that parameters file in the jobs tab if you come down here at the bottom you'll see a number of tabs so in the jobs tab this is where we create our job go to the tab and you can either select the menu and create jobs or you can select the icon is the same as the jobs tab down here create jobs and this dialog has a number of fields in it but the only three that you care about is sample ID parameter file and raw file in sample ID this is similar to a header this is just information that will go in your actual sample your parameter file is the parameter file that I'll show you how to setup in just a second and your raw file is the file where your data will be saved running a scan from this window and from your parameters and hitting start here ensures that the data is saved automatically what happens is people will go and run a scan here and go to lunch and some not get back in time and someone who's signed up for the instrument right after them will come and run a scan over it and your data is gone that doesn't happen if you do it from the jobs tab the way to set up a parameters file is in a separate application and it's the link to it is on the toolbar down here and it's called XRD wizard when you open up the wizard you get the quick wizard page which is fine the only thing that you really care about is putting your name in here and determining your scan definition and verifying your generator voltage and current is what you want your scan type is locked coupled and continuous this is the standard way to do it this what this means is that

your detector will be following at two theta from your sample you put in your start value and your stop value in to theta your step size is also in two Thea it calculates the number of steps you put in your time and it will calculate the total scan time and this is important because you want to know how long your scan is going to take and that's an important thing to know when you're reserving your time for the instrument also you can see the generator voltage and current the default is forty and forty which is the maximum and if you want to change that you can do that here so I'm just going to open a file that is for training so you can see what one of those looks like so this is a very quick scan I've got it from 15 to 55 and my step size is 0.5 for purposes of demonstration that's perfectly fine if I wanted to do any analysis though that would be unreasonable the most analysis software need a number of data points for a peak in order to even recognize that the peak exists and so the maximum step size recommended is 0.1 but 0.02 is preferred so once you've filled all this in you can just save it as your name and it'll automatically put the dot dql extension on it and save it in the scan parameters file and I'm going to create a job and there's a little button here that will take me to the file folders I want to go up one in two parameter files I'm going to select my training and then my raw file select that and most people have a folder they've created for themselves and now once I've done that everything is loaded and ready to go my sample is in the chamber but the reason I'm not running it right away is that the parameter files power is for 40 kilovolts and 40 milliamps but the power that I have in the actual instrument is still 40 and 30 I want to always make sure that the blue which is the status matches whatever is in my parameter file before I hit the start button because the values that are in the parameter file take precedence so if I'm at 20 and 5 here and I hit start for parameter file that's 40 and 40 it will automatically ramp the power up to 40 40 without going through the steps and this is not healthy for this - now it's actually up to maximum power and I can go ahead and run my sample I recommend that you wait five minutes or so while it's at maximum power I have run a number of scans at different different times after getting it to maximum power and have noticed a small change in maximum intensity but for now since we're just doing a demo I'm just going to in hit the start button right here then the sample ID now has changed a demonstration it's loaded automatically loaded my start and stop and increment values and it's running the scan and it moved to stage and the detector automatically so everything is being done automatically we can see there's a number of Peaks already for this is alumina which is a NIST standard um this right now it's just drawing lines if I right-click in here and select dots I can actually see the data points and hopefully you can see right away that this would not be something that would be recognized in analysis software there's only one data point here and you really want a minimum of at least three on its way up and it's on its way down so that click indicates that it's finished that the dots the shutter is now open closed which means you can open the door and the power is still on and it's still at 40 and 40 it is not necessary to ramp the power down and you're finished we want to be able to keep it up if someone's right behind you it's better for it to stay up than it is to go up and down but if no one is using it for the rest of the day we do want it to go into standby mode so we just leave this open and leave it like it is you can minimize it get your data out of your scans make sure that you remember to fill in the log and you may remove your sample and you've finished your span your span file is automatically saved to a scan folder and we have a shortcut to it on the desktop what people do is they find their data when it's finished and with a USB Drive we also have a three and a half inch floppy and CD if whatever you have just find your sample and save it to your to whatever drive you have and this sample can be opened in x-ray defraction software designed for that so to open the door there's a big square open door button here it's the only button you ever want to push press it the alarm light starts to flash pull the handles out towards you and away when you're removing your sample you want to make sure that first that you have a hold of your sample but there's a little switch under here put your thumb outside of there and then flip the switch towards you do not resist the temptation to squeeze the switch and the pressure unit together this pressure unit is hollow aluminum and if you squeeze it like that you will bend it hang on to your sample flip the switch and remove your sample when your samples been removed you can close the doors no need to slam them verify the doors closed by checking the alarm light and you're finished you Milano The New School for Management and Urban Policy.