February 2002 Ž . Materials Letters 52 2002 304–312 www.elsevier.comrlocatermatlet Comparative study on phase development of lead titanate powders Jiye Fang a, ) , John Wang a , Leong-Ming Gan b , Ser-Choon Ng c a Department of Materials Science, Faculty of Science, National UniÕersity of Singapore, 119260 Singapore b Institute of Materials Research and Engineering, Faculty of Science, National UniÕersity of Singapore, 119260 Singapore c Department of Physics, Faculty of Science, National UniÕersity of Singapore, 119260 Singapore Received 30 March 2001; accepted 14 April 2001 Abstract Ž . Ultrafine lead titanate PbTiO powders in tetragonal form have been successfully prepared via two processing routes, 3 Ž . Ž . namely, conventional coprecipitation CPC and microemulsion-refined coprecipitation MCP . The formation process of lead titanate from the resulting precursors was monitored using techniques such as thermal analyses, FTIR spectroscopy, Raman scattering spectroscopy and X-ray diffraction for the phase identification. It was found that the microemulsion-re- fined processing route led to a lower formation temperature for lead titanate than that observed in the conventional coprecipitation route, and there is no detectable pyrochlore phase during the formation of PbTiO in the former case. The 3 two PbTiO powders have also been comparatively studied in particle morphology and specific surface areas. It indicates 3 that the microemulsion-refined coprecipitation is the technique that results in the formation of the finer powder of lead titanate than the conventional coprecipitation does in the present work. q 2002 Elsevier Science B.V. All rights reserved. Keywords: Lead titanate; Microemulsions; Ultrafine powder; Coprecipitation; FTIR and Raman spectra 1. Introduction Ž . Lead titanate PbTiO , which exhibits a per- 3 ovskite structure and a Curie temperature of 490 8C, belongs to the most important ferroelectric and wx piezoelectric families 1. It has many important technological applications in electronics and micro- electronics, because of its high Curie temperature, high pyroelectric coefficient and high spontaneous w x polarisation 2,3 . There are at least two incentives in preparing an ultrafine lead titanate powder, prefer- ) Corresponding author. Advanced Materials Research Institute, SC2015, University of New Orleans, New Orleans, LA 70148, USA Fax: q 1-504-280-3185. Ž . E-mail address: jfang1@uno.edu J. Fang . Ž. ably in the range of nanometers: i to lower the wx ferroelectric phase transformation temperature 4; Ž. and ii to improve the sintering behaviour of this wx material 5 . For this, a number of chemistry-based processing routes have been employed, including w x sol–gel synthesis 6–11 , hydrothermal reactions w x w x 12–18 , coprecipitation 19–23 , molten salt prepa- w x w x ration 24 , solvothermal synthesis 25 , polymerized w x w x complex 26 and emulsion technique 27 . The de- gree of success of these techniques in preparing an ultrafine lead titanate powder varies considerably from one to another. Inverse microemulsion technique has been suc- cessfully used to prepare a range of ultrafine pow- w x w x ders, including oxides 28,29 , carbonates 30 , silver w x chloride and bromide 31,32 , high-temperature 00167-577Xr02r$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. Ž . PII: S0167-577X 01 00411-6