  We have grown single crystals of the type-VIII intermetallic clathrate
Ba8Ga16Sn30 from both Sn and Ga flux, evaluated their compositions through
electron microprobe analysis and studied their transport properties through
measurements on temperature dependent resistivity, thermopower and Hall
coefficient. Crystals grown in Sn flux show n-type carriers and those from Ga
flux show p-type carriers, whereas all measured compositions remain very close
to the stoichiometric 8:16:30 proportion of Ba:Ga:Sn, expected from
charge-balance principles. Our results indicate a very high sensitivity of the
charge carrier nature and density with respect to the growth conditions,
leading to relevant differences in transport properties which point to the
importance of tuning this material for optimal thermoelectric performance.
