X-ray structure refinement, vibrational spectroscopy, and ionic conductivity of Na0.11Ca9.64Sm0.23(PO4)6F2

Abstract

The present paper is interested in the study of compounds from the apatite family, which is an apatite structure of individual rare earth substituted fluorapatite. In fact, an Sm-Bearing fluorapatite Ca 10-2y Na y Sm y (PO 4 ) 6 A 2 with x=0.11 and y=0.23 has been synthesized by solidstate reaction and characterized by X-ray powder diffraction. The site occupancies of substituents are 0.01091 for Sm and 0.02601 for Na in the Ca(1) position and 0.05317 for Sm in the Ca(2) position. Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit cell group analyses and in comparison with fluorapatite and other fluorapatites. In addition to the proton conduction, the possibility of a Na + contribution to the conductivity in the high-temperature phase is proposed. The highest overall conductivity values were found at σ 475°C =2.03×10−5 S cm −1 and Ea=0.60 eV.

Bubble Formation in Apatite Structures by He-Ion Irradiation at High Temperature*

“…Figures 2(c) and 2(d) give the Raman spectra of Ca 10 (PO 4 ) 6 F 2 and Ca 10 (PO 4 ) 6 (OH) 2 , and four asymmetric stretching vibrations are observed below 1200 cm −1 , which arise from 𝜐 2 , 𝜐 4 , 𝜐 1 and 𝜐 3 for PO 3− 4 group in sequence. [13] The two broad bands around 1350 and 1600 cm −1 have been attributed to fluorescence emission band that may be caused by rare earth impurities. [14] The intensity reduction of GIXRD diffraction peaks and the obvious intensity drop of Raman modes indicates the ion irradiation induced amorphization of grains with PO 3− 4 tetrahedra distortion to some extent.…”