Reactive sintering of phosphorous coated BaTiO3

Doping BaTiO3 with P5+ has been reported to decrease the sintering temperat ure of the ceramic, allowing homogeneous line grained microstructures to be obtained. According to the present paper, the formation of a phosphorous-B aO rich phase covering the BaTiO3 particles seems to be the origin of the i mproved porosity coalescence and removal observed at the earlier sintering stage of these materials. The formation and development of phosphorous-bari um rich phases have been followed by means of DRX, and high temperature NMR . Phosphorous cations incorporated from phosphate estes form a surface laye r covering the BaTiO3 particles which reacts during heating to form Ba2TiP2 O9 and/or Ba-3(PO4)(2). Formation of these phases seem to occur by solid-so lid reaction involving phosphorous diffusion through the BaTiO3 particles. (C) 1999 Elsevier Science Limited. All rights reserved.