Composition Dependence of the Transition Temperature for Non-Stochiometric Ferroelectric Lithium Niobate

• Published in: Ferroelectrics Vol. 369; no. 1; pp. 53 - 57
• Main Authors: Aragó, C., Marqués, M. I., Plaza, J. L., Gonzalo, J. A., Wang, C. L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Taylor & Francis Group 01.01.2008; Taylor and Francis
• Subjects: Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Equilibrium properties near critical points, critical exponents; Exact sciences and technology; General studies of phase transitions; Physics; Effective field approximation; Stoichiometry; Solid solutions; Phase transformations; Critical points; Lithium niobates; Nonstoichiometry
• ISSN: 0015-0193; 1563-5112
• DOI: 10.1080/00150190802375102

The transition temperature T C (x) for non-stoichiometric lithium niobate, LiNbO 3 , here denoted by (Li 2 O) x (Nb 2 O 5 ) 1 − x where 0.465 < x < 0.500, evolves from T C (0.465) ≅ 1290 K to T C (0.50) ≅ 1485 K. Using an effective field approach, as done in previous works for isomorphous ferroelectrics solid solutions, we investigate the composition dependence of the critical temperature in this narrow range for ferroelectric lithium niobate. Experimental data are fitted by the function T C (x), deduced from the effective field theory when considering the short composition range of LiNbO 3 as a mixed system with increasing stoichiometry.