Accounting the Eccentricity of a Polycrystalline Sample in the Debye–Scherrer Scheme. Certification of a New Y2O3 XRD Standards

Issues related to the procedure of optimizing the calibration of modern area-detector diffractometers using reference single crystals are considered. It is shown that the accuracy of measuring the unit cell parameters (UCPs) of polycrystalline samples in the Debye–Scherrer scheme can be improved by considering the eccentricity. The procedure is tested on a CeO2 polycrystalline sample (SRM674b). The value obtained for the cubic unit cell parameter a = 5.4117(2) Å differs from the reference one by 0.0002 Å, in agreement with the experiment′s absolute error. The XRD certification of a promising Y2O3 XRD standard is performed (TU 48-4-524-90; ItO-V grade; 99.999% purity; cubic unit cell parameter a is 10.6047(3) Å).