TEOS was dissolved in water and ethanol solution. Then, 2M nitric acid was added to this mixture.
Continuous magnetic stirring was carried out for one hour.
Subsequently TEP, Ca(NO3)2·4H2O and lithium nitrate were added consecutively to the mixture, while allowing continuous stirring for one hour after each addition.
the mixture was placed in a conventional ultrasonic bath for one hour.
Meanwhile, 2M ammonia solution was slowly poured into the mixture, while it was strongly mixed with a mechanical stirrer.