Hollow microspheres formed by nanograins of Cr1.8Ti0.2O3+z synthesized by ultrasonic spray pyrolysis for acetone detection

•We have obtained Cr1.8Ti0.2O3+z (CTO) by spray pyrolysis technique.•The sample consists of hollow microspheres with walls formed by nanograins.•The sample presents a para- to antiferro-magnetic transition at 306 K.•CTO grown by spray pyrolysis has good sensitivity to acetone vapor.•CTO has excellent perspectives as volatile organic compounds sensor material.