Lead titanate crystals

Lead antimonate [13510-89-9] (Naples yellow), Pb2(Sb0 2> mol wt 993.07, d = 6.58g/cm, is an orange-yeUow powder that is insoluble in water and dilute acids, but very slightly soluble in hydrochloric acid. Lead antimonates are modifiers for ferroelectric lead titanates, pigments in oil-base paints, and colorants for glasses and glazes (see Colorants for ceramics). They are made by the reaction of lead nitrate and potassium antimonate solutions, followed by concentration and crystallization. 

Lead zirconate [12060-01 -4] PbZrO, mol wt 346.41, has two colorless crystal stmctures a cubic perovskite form above 230°C (Curie point) and a pseudotetragonal or orthorhombic form below 230°C. It is insoluble in water and aqueous alkaUes, but soluble in strong mineral acids. Lead zirconate is usually prepared by heating together the oxides of lead and zirconium in the proper proportion. It readily forms soHd solutions with other compounds with the ABO stmcture, such as barium zirconate or lead titanate. Mixed lead titanate-zirconates have particularly high piezoelectric properties. They are used in high power acoustic-radiating transducers, hydrophones, and specialty instmments (146). 

Piezoceramics are currently no longer manufactured from BaTi03, but from lead titanate zirconate, Pb(Ti,Zr)03, which aLso crystallizes in a perovskite lattice. Ceramic capacitors to a value of 4.1 10 DM were produced in 1995, ca. 50% of the turnover for functional ceramics, in which the three region USA, Japan and Europe have equal shares. 

Shastry, S., Srinivasan, G., Bichurin, M.I., Petrov, V.M., and Tatarenko, A.S. (2004) Microwave magnetoelectric effects in single crystal hilayers of yttrium iron garnet and lead magnesium niohate-lead titanate. Phys. Rev. B, 70 (6), 064416. 

P, Han, W. Yan, J. Tian, X. Huang, and H. Pan, Cut directions for the optimization of piezoelectric coefficients of lead magnesium niobate-lead titanate ferroelectric crystals , Appl. Phys. Lett, 86, 052902, (2005). 

Lead titanate exhibits only one stmctural phase transition from paraelectric cubic mhm to ferroelectric tetragonal 4mm phase. Curie temperature is relatively high 490° C. Lead titanate has the biggest anisotropy in the tetragonal lattice parameter ratio c/a = 1.06 among all perovskite crystals. Due to the anisotropy it exhibits relatively high hydrostatic piezoelectric coefficient dh (higher than PZT ceramics). 

Lead titanate is mainly used for the pyroelectric detector elements, for the hydrophone applications and as a high-temperature ceramic material. PbTiOs single crystals are not commercially available in desired size and quality. 

Li Z, Grimsditch M, Xu X, Chan SK (1993) The elastic, piezoelectric and dielectric constants of tetragonal PbTiOs single crystals. Ferroelectrics 141 313-325 MarraSP, Ramesh KT, Douglas AS (1999) The Mechanical properties of lead-titanate/polymer 0-3 composites. Compos Sci Technol 59 2163-2173 Materials Data Sheets of APC International, Tokin, Ferroperm, Morgan Matroc, Siemens Mattiat OE (1971) Ultrasonic transducer materials. Plenum Press, Tokyo McLachlan DS, Blaszkiewicz M, Newnham RE (1990) Electrical resistivity of composites. J Am Ceram Soc 73 2187-2203... 

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... 

Lynch and Shelby (1984) examined the reasons for the high dielectric properties of lead titanate glass-ceramics. They defined the matrix phase around the ferroelectric crystals. They also determined a special effect they called clamping. This phenomenon occurs when the glass matrix contracts and produces compressive stress within the ferroelectric particles, causing paraelectric-to-ferroelectric phase transition. As a result, the crystal size must be controlled for electro-optic applications. The crj tals should preferably be smaller than 0.1 pm. 

Lynch S.M. and Shelby, "Crystal Clamping in Lead Titanate Glass-Ceramics," J. Am. Ceram. Soc., 67, 424-27 (1984). 

The ceramic materials used consisted of lead zirconate—lead titanate mixtures. These materials have relatively square hysteresis loops and can be prepared in large thin plates. Tlie thickness of the ceramic layer was of the order of 100 jum, that of the liquid crystal about 10 Mm. With a thickness of about 50 jum, these ceramic mixtures have a sufficient transparency, so that a matrix which also operates in transmitted light can be realized. 

Powders from Alkoxides and Salts. Two solutions were prepared individually for the synthesis of lead titanate (PbTiOs) particles by Tartaj et al. (2001) (i) titanium tetra-butoxide in 2-propanol, and (ii) lead acetate in glacial acetic acid. The solutions were mixed under stirring, and a water-2-propanol mixture added to this for the initiation of hydrolysis. As in some other cases, crystalline seeds of the target compound, suspended in 2-propanol, were added (10 wt%) to the transparent sol already obtained. The gels obtained through this process were dried and ground to small particles and calcined at 400°C for 20 h for use in the preparation of sintered bodies. X-ray diffractometry of the calcined sample showed it to be fully crystallized to phase-pure PbTiOs, while an unseeded sample did not crystallize under the same conditions. 

Toyoda M. Effect of catalyst on the crystallization of lead titanate precursor fibers derived from sol-gel (in Japanese). Nihon-Kagakukai-Shi 1997a 1997 851-856 Toyoda M., Hajime Y., Tomono K. Preparation of PbTiOs ceramic fibers by sol-gel processing. J. Sol-Gel Sci. Technol. 1997b 9 71-84... 

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