![]() Hit "OK" and bring up the "Movie Properties" dialog boxes again. Minimize the movie dialog boxes again, hit "ctrl-n" again and keep repeating this sequence of steps until all the datasets have been viewed and put into the movie sequence." Essentially you just keep hitting "ctrl-n" "alt-1" "OK", "Movie Properties", "Append Frame" over and over again, until the dialog box comes up that tells you there is no more data in the file. So restore the "Movie Properties" dialog box by clicking on it in the taskbar, and click the "Append Frame" button again. We should now have an image that is the next one in our animation sequence. The limit parameters are unchanged from the last time we selected them. This click will minimize the two dialog boxes and make the XtalDraw window active. Then click on the XtalDraw window, off of the "Frames" and "Movie Properties" dialog boxes. This option will center the image at the origin of the crystal structure and draw the atoms out to +/- 1 unit cell. A dialog box opens and you should enter a value of 1 in the edit box and select the radio button "fractional a from origin". This option provides an interface to changing the number of atoms drawn with a single parameter. Next, we will add more polyhedra to the image for aesthetic appeal by choosing "View" and then "Alter Structure Limits" and then "1" (alt-1).If the unit cell is currently displayed, then turn it off by choosing "Display" and then "Unit Cell" (alt-u). The animation is particularly effective when the structure is viewed as polygons, so set up the drawings by choosing "Display" and then "Polygons" (alt-g).The first structure should be displayed in the XtalDraw window. Then click on the hyperlink "Click here to download this data in. We will choose the structures at roughly 100° intervals, so click in the check boxes beside each dataset for the data at 298, 398, 498, 597, 697, 813, 891, 9 K and then click on "Process Selected Data". There are 17 datasets of quartz from this paper, but we will only use a subset of them to illustrate the animation. Go to the American Mineralogist Crystal Structure Database and conduct a search with "quartz" in the mineral field and "Kihara" in the author field.The following instructions are for XtalDraw. In this exercise, we will create a movie that shows the change of quartz as a function of temperature, through the α- β transition using the published data of Kihara (1990). Kihara, in 1990, conducted the best X-ray diffraction study of the evolution of quartz from room temperature through the α- β transformation to 1078 K. The high-temperature form is not quenchable, meaning that as temperature drops, β quartz always transforms to α quartz. At around 843 K, the symmetry of quartz changes from trigonal to hexagonal in what is known as a displacive phase transition in which no bonds are broken. One of the most famous and most studied phase transitions in minerals is the transformation of quartz from the α to the β phase as a function of temperature. Using XtalDraw to Make Animated GIF's: The High-Temperature Phase Transition of Quartz ![]()
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