A new idea for specific surface area standard reference materials (SRM) which are made of nonporous mono-disperse SiO2 spheres and the true specific surface area can be calculated accurately from their diameters is presented.Firstly,the mono-disperse SiO2 spheres were synthesized in bulk.Secondly,the spheres were modified to make them nonporous.Thirdly,the characteristic dimensions,such as the size,density of the spheres,were determined accurately.Finally,the specific surface areas were measured by using a static volumetric type Brunauer-Emmett-Teller (BET) (nitrogen gas) instrument.The experimental results showed that the micro-holes on the surface of mono-disperse SiO2 spheres were almost be sealed by calcining at the temperature of 1000℃ for three hours.The BET surface area was larger than the geometric specific surface area and the values of the deviation were 1.2 m2·g-1,2.0 m2·g-1 and 3.6 m2·g-1 for mono-disperse SiO2 spheres with diameters 1150 nm,453 nm and 269 nm respectively.In this case,the theoretical value can be used as reference for the determination of the specific surface area of nonporous mono-disperse SiO2 spheres SRMs.
