Zinc niobates

There are a whole range of lead-containing relaxors based on lead zinc niobate (PZN), lead iron niobate (PFN), lead iron tungstate (PFW), and solid solutions with each other and with BaTiOs (BT), PbTi03 (PT), and SrTiOs (ST). Some of the solid-solution phases are PMN-PT, PMN-PT-PZN, PMN-PZN, PFN-PFW, PFN-PMN, and PFW-PT. 

Kamzina LS, Krainik NN (1998) Electric-field-induced phase transition in single-crystal lead zinc niobate. Phys Solid State 40 485 88... 

Mulvihill ML, Cross LE, Cao WW, Uchino K (1997) Domain-related phase transitionlike behavior in lead zinc niobate relaxor ferroelectric single crystals. J Am Ceram Soc 80 1462-1468... 

Mulvihill ML, Park SE, Risch G, Li Z, Uchino K (1996) The role of processing variables in the flux growth of Lead zinc Niobate-Lead titanate relaxor ferroelectric single crystals. Jpn J Appl Phys 35 3984 3990... 

More recently, because of their high dielectric constants k > 20 000), lead-based relaxor ferroelectrics have been used as capacitor materials. These ceramics have the general chemical formula Pb(5i, 2)03) vvhere Bi is typically a low-valence cation and B2 is a high-valence cation. Compositions used in capacitor applications are frequently based on lead magnesium niobate, Pb(Mgi/3,Nb2/3)03, and lead zinc niobate, Pb(Zni/3,Nb2/3)03. Other substituents and modifiers are added so that dielectric layers of these materials can be densified at relatively low temperatures ( 900 °C). The low firing temperatures permit the use of relatively inexpensive cofired electrode materials, such as silver. Typically, tape casting is used in the preparation of the dielectric layers. 

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