A pyrogenically prepared silicon dioxide powder (C1) in the form of aggregated primary particles has statistical thickness surface area (STSA) of 10-500 m2>/g; thickening action, based on the STSA surface area of 4-8 mPasx g/m2>; and micropore volume of 0.03-0.07 cm3>/g. Independent claims are included for following: (1) preparing the pyrogenic silicon dioxide powder (C1) involving, mixing at least one hydrolyzable silicon compounds, oxygen-containing gas and/or primary combustion gas; igniting the mixture in a burner, burnt via pipe into a reaction chamber; passing secondary combustion gas into the reaction chamber and separating powder formed from gaseous substances, where the hydrogen ratio gamma(primary) of the raw material mixture is less than 1 and oxygen ratio lambda(primary) of the raw material mixture is greater than 1, gamma(primary) is defined as the combustion gas fed to the mixing chamber divided by the combustion gas required stoichiometrically and lambda(primary) is theoxygen supplied to the mixing chamber divided by the oxygen required stoichiometrically; and (2) a dispersion containing the pyrogenically prepared silicon dioxide powder (C1).