Process for the manufacture of ferroelectric materials

摘要

A process for the preparation of a niobium compound of formula (I):
DαNbβEγO3-δ  (I)whereinD is an alkali metal (e.g. Li, Na, K, Rb, Cs and/or Fr), alkaline earth metal (such as Ba, Ca, Mg and/or Sr), La and/or Bi and may be present as a mixture of two or more metals;E is Ta, Sb and/or Fe and may be present as a mixture of two or more metals;α is a positive numberβ is a positive numberγ is zero or a positive numberδ is a number 0≦δ≦0.5;and wherein the formula (I) has the perovskite or tungsten bronze structure;comprising spray pyrolising a solution, for example an aqueous solution, comprising metal (D) ions, Nb ions and if present, metal (E) ions.

主权项

1. A process for the preparation of an alkali metal niobium oxide of formula (Ia):
A1-2x-3wBxCwNb1-y-3/5z-uTayFezSbuO3  (Ia) wherein A is Li, Na, K, Rb, Cs, Fr, or a mixture thereof; B is Ba, Ca, Mg, Sr, or a mixture thereof, C is La, and/or Bi; 0≦u≦0.3; 0≦w≦0.3; 0≦x≦0.3, 0≦y<1 and 0≦z≦0.3, the values of u, w, x, y and z being independent of each other with the proviso that the sum of y+3/5z+u is less than 1 and with the proviso that the sum of 3w+2x is less than 1; comprising spray pyrolising an aqueous solution, comprising alkali metal (A) ions, Nb ions and optionally alkaline earth ions (B), Ta Sb, La, Bi, and/or Fe ions, to form a powder and calcining said powder.