Sol‐Gel Synthesis, X‐Ray Diffraction Studies, and Electric Conductivity of Sodium Europium Silicate

Abstract

Sodium europium silicate, NaEu9(SiO4)6O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4) atoms not related to silicate ions are placed at the centers of Eu(2) triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied.

Low-temperature formation of apatite structure of neodymium silicate in silica matrix

“…Temperature scale of the phase diagrams denotes from about 1400 °C due to the perfect structure formation of the silicates under hightemperature synthesis. But the temperature can be reduced by using modern methods of synthesis with suitable precursors, such as different modifications of sol-gel synthesis, thereby good miscibility of the components and homogeneity of reaction mixture are achieved [9][10][11][12]. In our previous research [13][14][15][16], concerning to phase transformations in the composites based on rare earth oxides and fumed alumina and silica, neodymium silicate was detected with apatite type structure at nontypical ratio of Nd 2O3 and SiO2 as 1:16 and annealing temperature of 1050 °C.…”