Crystal Growth and Temperature Evolution of the Atomic Structure of Pr3Ga5SiO14 from the Langasite Family

Abstract

Pr3Ga5SiO14 crystals from the langasite family have been grown by the floating zone melting technique. Their X-ray diffraction analysis is performed at 16 different temperatures in range of 94–293 K. An experiment with ultrahigh resolution at 94 K has yielded the most exact structural model: sp. gr. P321, Z = 1, a = 8.07636(4) A, c = 5.06586(2) A, R1/wR2 = 1.192/1.185%, and Δρmin/Δρmax = –0.93/+0.79 e/A3 for 3852 unique reflections and 123 refined parameters. The temperature evolution of atomic displacement parameters is estimated based on multitemperature data using the extended Einstein and Debye models. Static components of atomic displacements are selected and the characteristic Einstein and Debye temperatures for structure atoms are determined. No structural anomalies have been found.