Strontium–barium niobate single crystals, growth and ferroelectric properties

• Published in: Journal of crystal growth 2008-04, Vol.310 (7), p.1464-1469
• Main Authors: Lukasiewicz, T., Swirkowicz, M.A., Dec, J., Hofman, W., Szyrski, W.
• Format: Article
• Language: English
• Subjects: A2. Czochralski method; B1. Niobates; B2. Ferroelectric materials; B2. SBN; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Growth from melts; zone melting and refining; Materials science; Methods of crystal growth; physics of crystal growth; Niobates, titanates, tantalates, pzt ceramics, etc; Physics
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2007.11.233

Single crystals of strontium–barium niobate Sr x Ba 1− x Nb 2O 6 (SBN) undoped and doped with Ce or Cr were grown by the Czochralski method. The inductive heating system was used. In order to improve conditions of growth, a crucible-base cooling was introduced. Single crystals of the following nominal compositions have been obtained: Sr 0.4Ba 0.6Nb 2O 6, Sr 0.5Ba 0.5Nb 2O 6, Sr 0.61Ba 0.39Nb 2O 6 (congruent melting) and Sr 0.75Ba 0.25Nb 2O 6, designated hereafter as SBN40, SBN50, SBN61 and SBN75. They were up to 22 mm in diameter and 40 mm in length with characteristic 24 faces, free from striations and other extended defects. All the crystals were grown in the [0 0 1] direction. The dopants (Ce or Cr) were added to the SBN61 composition. By use of ICP-OES method, the chemical compositions were checked. Etch pit density was also measured. In the case of the undoped single crystals, it was found to be 2.4×10 2–5.6×10 3 cm −2 but in the case of Ce or Cr doping, it increased up to 3.6×10 4–1.8×10 5 cm −2. Investigations of the linear dielectric response measured within 10 0⩽ f⩽10 5 Hz along the polar c-axis of four obtained single-crystalline SBN compounds revealed a gradual crossover from conventional ferroelectric (SBN40) to extreme relaxor (SBN75) behavior.