Patent ID: 6534429
Filing Date: 2003-03-18
Classification: C04B,C23C,H01L

Abstract:
A method of preparing a multi-component material having a specific desired Curie point represented by the general formula (I):Ba(1âˆ’xâˆ’y)PbyMxTiO3â€ƒâ€ƒ(I) in which:M is selected from the group consisting of Sr or Cd; x is the decimal fraction molar concentration of MTiO3, where x has a value equal to or greater than 0.20 and less than or equal to 0.75; y is the decimal fraction molar concentration of PbTiO3, where y has a value greater than zero and less than or equal to 0.40, and x+y is less than 1.0; comprising the steps of:selecting a value of said x; locating a first point on a first graphical representation comprising a temperature axis representing Curie points in Â°C. and a concentration axis representing mole percentage of BaTiO3 and MTiO3, said first point corresponding to the intersection of an abscissa representing said x expressed as a percentage with an ordinate representing a specific desired Curie point temperature T between about âˆ’40Â° C. to 60Â° C.; locating a second point on said first graphical representation corresponding to the intersection of an abscissa representing 100% MTiO3 with an ordinate representing a temperature of âˆ’220Â° C.; drawing a straight line from said second point through said first point, and extending said line to intercept said temperature axis and a scale representing the decimal mole fraction of PbTiO3 in the BaTiO3/PbTiO3 system at a third point; multiplying said decimal mole fraction of PbTiO3 identified by said third point by a value equal to 1âˆ’x to determine a value of said y; mixing powders of BaTiO3, PbTiO3 and MTiO3 in the calculated fractional molar concentrations; and sintering the mixture to produce the desired multi-component material.