Forty crystal structure analyses of KH2PO4 in the paraelectric phase

A resolving power of the structure analysis is governed by the accuracy of the diffraction intensity measurement. This fact implies that adjacent disordered positions can be distinguishable on the histogram in position derived from a number of split-atom structure analyses. To find the true P atom position (s) of KH2PO4 (KDP) in the paraelectric phase along this line, we collected forty X-ray diffraction intensity sets and carried out the split-atom structure refinement. Analyzing the derived histograms of the P atom position for several structure models, we conclude that the average structure model is most probable to indicate the ferroelectric phase transition of KDP is of the displacive-type.