 Since the early 20th century, X-rays have been used to determine structure of materials through diffraction. Today, X-ray diffraction, or XRD, is a common characterization tool for material scientists. XRD is used to generate a diffraction pattern corresponding to the crystal symmetry of the material. The type of pattern and its position can give information about crystal structure and lattice parameters, and other information can be determined such as residual stress, crystal size, and oriented growth. This video will show the operation for one-dimensional X-ray diffractometry using a Brucker D8 focus instrument. Upon entering the XRD room, the user should take notice of the operational lights on the side of the instrument. The ready and on lights should be illuminated, while the alarm and busy lights should be off. To unlock the doors, the user presses the open door button. The alarm light will blink while the doors remain unlocked. To open the doors, the user pulls the two black handles towards themselves simultaneously, then gently slides the doors apart by the metal fixtures. X-rays are generated by accelerating electrons into a copper target. X-rays are directed towards the sample where they diffract. Angles of constructive interference will diffract X-rays into the one-dimensional detector, which transduces the X-ray intensity. The X-ray beam leaving the X-ray generator is confined by the divergent slit. The length of the sample that is illuminated by X-rays depends on the diffraction angle and divergent slit size. A narrower divergent slit produces sharper diffraction peaks at lower intensity that can help resolve closely spaced peaks. On the detector side, there is an anti-scatter slit, which reduces noise caused by scattered X-rays from amorphous material or air. The diffraction slit further controls the resolution of the instrument. In between the two slits is a piece of nickel foil. Nickel has an X-ray absorption edge between copper K-alpha and K-beta, causing it to absorb more of the higher energy K-beta X-rays while letting more of the K-alpha X-rays pass through it. There are various types of sample holders for different samples. No matter what type of holder is used, it is important that the surface of the sample is flush with the top surface of the sample holder. This sample holder has an adjustable stage to change the height of the sample. After loading a sample, the sample holder is placed onto the base of the sample stage fixture. The sample holder is lifted up from above so that its top surface is flush with the top of the sample stage. Then, the sample stage fixture is gently pressed up, locking the sample holder into position. The doors are closed by gently sliding them together by the metal fixtures, and then locked by pressing the black handles in simultaneously. When the doors are locked, the alarm light will stop blinking and remain off. Now it's time for the user to set up the scan using the instrument software. A scan method can be created or modified using the XRD Wizard application from the desktop. From the application screen, a new method or previous method can be opened. The user can set the 2-theta scan range, step size or number of steps per scan, and time per step. The X-ray generator power for the scan can be adjusted up to 40 kV and 40 mA. Finally, the scan method is saved. Operation of the instrument is done through the XRD Commander application. Before starting a scan, the X-ray generator power must be slowly ramped up to its desired output. First, voltage is increased at 5 kV increments by typing in the next value and clicking the set button. The X-ray generator is allowed to rest for 10 seconds before the user increases to the next set point. This slow ramp in power will ensure increased longevity of the X-ray generator. Next, the current is increased at 5 mA intervals in the same manner. After the target power has been achieved, the user can set up the next scan by clicking on the jobs dropdown menu and selecting jobs. This will open a new window where the user can add a sample ID, select a parameter file, and save location for their sample. The user starts the selected scan by pressing the start button. This will open the shutter of the X-ray generator and begin the scan. Two red lights are illuminated on the X-ray generator when the shutter is open and the goniometer moves into its starting theta and two theta positions. This goniometer has a stationary X-ray source with moving sample stage and detector. But other XRD instruments may have a stationary sample stage with moving X-ray source and detector. During a scan, the busy light will be illuminated. When the scan has completed, the X-ray generator shutter will automatically close and the busy light will turn off. Now the sample is ready to be removed. The final position of the goniometer may make it difficult to remove the sample holder. The user can adjust the goniometer position manually by changing the theta and two theta values to 30 and 60 degrees and pressing the move drives button in the XRD commander application. To remove the sample holder from the sample stage, a latch underneath the sample stage is gently pulled while holding onto the sample holder. Before leaving, the status of the alarm light is checked. If the alarm is on, the user will contact the lab technician for assistance.