As noted, sample broadening is treated in GSAS-II as both a property of the phase (as there is no reason that two different phases would be expected to have the same crystallite sizes or microstrain) but also a property of the histogram (since the specimen used for each measurement might have differing sizes or morphologies.) One can define constraints that force the size parameters to be the same across datasets (which might be useful where the same batch of material was used for all measurements). I have used this for impurity phases, where too few peaks to fit broadening well for all phases. By default, these “HAP” parameters are found on each Phase’s Data tab, as seen in Fig. 14.3 where I have outlined the crystallite size values in yellow.
The phase is selected from the data tree and the histogram is selected from box to the upper left. Menu commands allow duplication of the parameter values between different histograms. Copying of values can be done where all values are copied (menu command “Copy data”) or where only selected values are copied (menu command “Copy selected data”). It is also possible to duplicate only the refinement settings (we call them refinement flags) with the “Copy flags” menu command. There is no mechanism at present for copying values between phases.
Note that GSAS-II offers a mode where these “HAP” values are placed in their own data tree entry. (I prefer this mode.) This mode is selected using the preference variable “SeparateHistPhaseTreeItem” as shown in Fig. 14.4.
When this is done, these entries are accessed in the Hist/Phase item in the data tree and the window has a slightly different appearance (note that phases are now selected using the tabs at the top of the window), as seen in Fig. 14.5.
