0020-1685/01/3712- $25.00 © 2001 MAIK “Nauka /Interperiodica” 1289 Inorganic Materials, Vol. 37, No. 12, 2001, pp. 1289–1293. Translated from Neorganicheskie Materialy, Vol. 37, No. 12, 2001, pp. 1510–1515. Original Russian Text Copyright © 2001 by Reznichenko, Dantsiger, Razumovskaya, Dudkina, Raevskii, Shilkina, Klevtsov. The physical properties of ferroelectric solid solu- tions are known to show extrema near morphotropic phase transitions [1–3]. This effect is very pronounced when morphotropic regions are investigated along secant rays [3]. At the same time, the variations in the properties of solid solutions along morphotropic boundaries (within the morphotropic region or outside it, 1–2 and 10–15 mol % away from the boundary) have not yet been studied. A physicochemical method for investigating mor- photropic regions in multinary systems was proposed by Fesenko et al. [3]. In this method, multinary systems are represented by multidimensional simplexes with a dimensionality smaller by unity than the number of com- ponents (tetrahedron at k = 4, pentatop for k = 5, and hexatop for k = 6). To find compositions with extremal properties in a Pb(Ti,Zr)O 3 – O 3 ) n system, the morphotropic region is investigated along rays emerging from the PbTiO 3 corner. The shape, boundary, and extent of the morphotropic region are refined by analyzing the structural and physical proper- ties of the solid solutions with compositions along these rays. By studying a large number of systems with k = 4–6, we accumulated a great body of experimental data on the properties of solid solutions both in the tetrago- nal (T) + rhombohedral (R) phase field and near the morphotropic boundary in the single-phase region. This allowed us to analyze the properties of solid solutions along morphotropic boundaries. We examined solid solutions based on lead zircon- ate titanate (PZT) in the systems PZT–PbNb 2/3 Zn 1/3 O 3 –PbNb 2/3 Mg 1/3 O 3 (1), PZT–PbNb 2/3 Co 1/3 O 3 –PbNb 2/3 Mg 1/3 O 3 (2), PZT–PbNb 2/3 Mg 1/3 O 3 –PbW 1/2 Ni 1/2 O 3 (3), (PbB 1 α – ' B α '' n 1 = n 4 = ∑ and PZT–PbNb 2/3 Zn 1/3 O 3 –PbW 1/2 Mg 1/2 O 3 (4). These solid solutions were investigated earlier in great detail over wide composition ranges [3]. The sys- tems in question offer the possibility to compare the properties of solid solutions containing isovalent (Nb– Nb) and heterovalent (Nb–W) B'–B''' combinations. Heterovalent substitutions may produce more complex changes in structure and, hence, in properties, e.g., owing to an increased vacancy concentration [3]. Figure 1a (taken from [3]) shows a composition tet- rahedron in which the ABC plane represents a morpho- tropic region and sections I–IV pass through the mor- photropic region in different directions. It can be seen that the regions common to the morphotropic region and one of the sections extend from the system Pb(Ti,Zr)O 3 –Pb O 3 (component K 3 ) to Pb(Ti,Zr)O 3 –Pb O 3 (component K 4 ) (sec- tions I–III) or from the system Pb(Ti,Zr)O 3 to Pb O 3 –Pb O 3 (section IV). The dashed lines indicate the T–R phase boundary. Figures 1b and 1c show secant rays in sections I and IV and the compo- sitions (crosses) along the rays analyzed earlier [3]. In this work, we consider compositions lying along the morphotropic region a fixed distance from it. Figure 2 displays the dependences of the uniform distortion parameter (δ) [4] and relative permittivity of poled samples ( /ε 0 ) on the content of the more soft- electric component along the morphotropic region in section I for different PbTiO 3 contents (specified at the curves in mol %). These data demonstrate that, in going from the sys- tem Pb(Ti,Zr)O 3 –K 3 to Pb(Ti,Zr)O 3 –K 4 (replacement of Pb O 3 by Pb O 3 ), there are two B 1 α – ' B α '' B 1 β – ''' B β '''' B 1 α – ' B α '' B 1 β – ''' B β '''' ε 33 T B 1 α – ' B α '' B 1 β – ''' B β '''' Properties of Multicomponent Solid Solutions Based on Lead Zirconate Titanate near Morphotropic Regions L. A. Reznichenko, A. Ya. Dantsiger, O. N. Razumovskaya, S. I. Dudkina, I. P. Raevskii, L. A. Shilkina, and A. N. Klevtsov † Research Institute of Physics, Rostov State University, pr. Stachki 194, Rostov-on-Don, 344090 Russia e-mail: klevtsov@ip.rsu.ru Received December 13, 2000; in final form, March 14, 2001 Abstract—The structural and dielectric ( /ε 0 ) properties of Pb(Ti,Zr)O 3 –Pb O 3 –Pb O 3 solid solutions were studied along the morphotropic region. Depending on the nature of the substituent cations, the properties of the solid solutions either vary monotonically with the content of the soft-electric component or exhibit extrema at a certain average electronegativity of the B-site cations. ε 33 T B 1 α – ' B α '' B 1 β – ''' B β '''' † Deceased.