A compositionally stratified multi-layer Ba1-xSrxTiO3 (BST) heterostructure material is described which includes a lower layer of crystallized Ba1-xSrxTiO3 perovskite oxide where x is in the range of 0.36-0.44, inclusive, deposited on a substrate; an intermediate layer of crystallized Ba1-xSrxTiO3 perovskite oxide where x is in the range of 0.23-0.27, inclusive, in contact with the lower layer; and an upper layer of crystallized Ba1-xSrxTiO3 perovskite oxide where x in the range of 0.08-0.13, inclusive, in contact with the intermediate layer. A phase shifter and/or preselector tunable device including a compositionally stratified multi-layer BST heterostructure material is described according to the present invention. Temperature sensitivity of an inventive phase shifter is reduced by at least 70% in the temperature interval of 20 to 90° C., inclusive, and by at least 14% in the temperature interval of −10 to 20° C., inclusive, compared to a compositionally homogeneous 60/40 BST material.