Ceramics of lead magnesium niobium zirconium oxide, Pb(Mg(1-x)/3Nb2(1-x)/3Zrx)O3 (0 less-than-or-equal-to x less-than-or-equal-to 0-3), have been fabricated and characterised, with 'relaxor' ferroelectric properties shown by all compositions. Samples have been prepared in a two-stage 'mixed oxide' synthesis, with XRD studies confirming the existence of a solid solution for each composition in the range. A full dielectric characterisation has been carried out, with measurements made of epsilon(r)' and epsilon(r)'' versus temperature at five different frequencies between 100 Hz and 1 MHz. The variation of dielectric response with zirconium concentration, x, is described through the use of four empirical parameters, T(epsilon(r,max)'), epsilon(r,max)', and DELTAT', which are derived from the variation of epsilon(r)' with temperature. A rationalisation of the observed trends is given, employing the 'polarisation cluster' conceptual framework. Consideration of the properties of NbO6, MgO6 and ZrO6 cation coordination polyhedra permits an understanding of the compositional dependence of the 'relaxor' response, which is helpful in the design of new compositions with desirable dielectric properties. The dielectric behaviour of the related system Pb(Mg(1-x)/3Nb2(1-x)/3Tix)O3 can also be understood in these terms.
