Morphotropic phase boundary and dielectric properties of V2O5-containing SrxBa1-xNb2O6(0.2<=x<=0.4) ferroelectrics

SrxBa1-xNb2O6 (0.2 less than or equal to x less than or equal to 0.4: SBN) ceramics were fabricated by pressureless sintering with the addition of V2O5 (1 mol%) which considerably accelerated grain growth. X-ray diffraction analysis of elongated grains indicated that there is a morphotropic phase boundary between x=0.25 (tetragonal) and x=0.225 (orthorhombic) in the SBN system. The sharpening of a ferroelectric phase transition peak was maximum at x=0.2. This corresponded to a cation distribution in which the A(2)-sites in the tungsten bronze structure were fully occupied by Ba2+ ions. A phase transition temperature diagram was developed for the present composition region.