This invention provides the three novel La,Fe, La,Cr and Sm,Fe substituted barium titanate solid solution ferroelectric compositions with the formula Ba.sub.1-xLn.sub.xTi.sub.1-xM.sub.xO.sub.3 wherein when Ln is La, M is Fe or Cr, when Ln is Sm, M is Fe and x is from about 0.02 to about 0.06 and mixtures thereof, the novel La,Fe substituted barium strontium titanate solid solution ferroelectric compositions with the formula (Ba.sub.1-ySr.sub.y).sub.1-xLa.sub.xTi.sub.1-xFe.sub.xO.sub.3 wherein y is greater than zero and less than about 0.6 and x is from about 0.01 to about 0.06 and the novel La,Al substituted barium strontium titanate solid solution ferroelectric compositions with the formula (Ba.sub.1-ySr.sub.y).sub.1-xLa.sub.xTi.sub.1-x/4-3a/4Al.sub.a.sub.(x-a)/4- O.sub.3 wherein denotes a vacancy, y is greater than zero and less than about 0.6, a is from about 0.01 to about 0.06 and x is from 0.02 to about 0.10 with the proviso that x is greater than or equal to a.These low loss tunable ferroelectric compositions are especially useful in tunable microwave thin film devices which fall into three types: interdigital and trilayer capacitors, coplanar waveguides and microstrips.