Synthesis and characterization of β-Yb2Si2O7 powders

Abstract β-Yb2Si2O7 powders were synthesized by a sol–gel method using ytterbium nitrate and tetraethyl orthosilicate as starting materials. The thermal history, influence of composition and calcining temperature on phase evolution of the gel were investigated using TG–DTA, FTIR and X-ray diffraction. Amorphous Yb2Si2O7 formed below 950 °C and a low-temperature phase (α-Yb2Si2O7) was detected in powders calcined at 1000 °C and 1100 °C. Well crystalline β-Yb2Si2O7 powders were obtained after calcining the xerogel at 1200 °C for 2 h. The average particle size of the powders calcined at 1200 °C was ∼300 nm. The crystallite size determined from both TEM and FWHM of XRD reflections was ∼60 nm. Lattice parameters of β-Yb2Si2O7 determined by Rietveld method were a=6.80053 A, b=8.87508 A, c=4.70740 A and β=101.984°. Atomic positions of β-Yb2Si2O7 were identified as Yb(0.5, 0.80548, 0),Si(0.74150, 0.5, 0.42936), O(1) (0.5, 0.5, 0.5), O(2) (0.89831, 0.5, 0.75248), O(3) (0.74229, 0.65022, 0.18086).