Application of normal probability plot analysis to lutetium orthoborate factors and parameters

Abstract

The methods of normal probability plot analysis have been applied to two nearly complete sets of structure factors (F meas) and the corresponding objectively assigned standard deviations (σF meas) obtained by diffractometer measurement with two different crystals of lutetium orthoborate. The least-squares derived positional and thermal vibration parameters are shown to be too small by a factor of 1.8, and the σF meas to be overestimated by a factor of 1.55. The two sets of F meas are found to contain a small but parallel bias. The lattice constants of rhombohedral calcite-type LuBO3 are measured as a H = 4.91538±0.00002 Å and cH = 16.21200±0.00003 Å at 298°K, with six formulas in the unit cell, space group R\overline 3c. The Lu–O distance in this six-coordinated Lu compound is 2.240±0.002 Å (corrected standard deviation). The B–O distance in the BO3 triangular groups is 1.370±0.005 Å. The characteristic Θ temperature is estimated as 446±19°K.