Abstract
Abstract Phase diagram analyses and crystal growth experiments of the novel ferroelectric tetragonal tungsten bronzes Ca x Ba 1 - x Nb 2 O 6 (calcium barium niobate, CBN) and Ca x Sr y Ba 1 - x - y Nb 2 O 6 (calcium strontium barium niobate, CSBN) were performed in this study. The quasi-binary phase diagram BaNb 2 O 6 – CaNb 2 O 6 was found to be similar to the related system BaNb 2 O 6 – SrNb 2 O 6 , but with a remarkably reduced existence region. In the quasi-ternary phase diagram CaNb 2 O 6 – SrNb 2 O 6 – BaNb 2 O 6 the stability field of Ca x Sr y Ba 1 - x - y Nb 2 O 6 mixed crystals was determined by X-ray powder diffraction of sintered and annealed samples. Large, transparent, and nearly colorless CBN and CSBN single crystals of high quality were grown by the Czochralski method. The dislocation network structure of the core region in the as-grown crystals was analyzed by X-ray topography employing white beam synchrotron radiation. Precise measurements of the refractive index dispersion showed a composition dependance only for the extraordinary beam. The Curie temperature of the ferroelectric phase transition 4 m mm → 4 mm determinated by calorimetric measurements exhibited a clear composition dependance. It is expected that in the complete mixed crystal system Ca x Sr y Ba 1 - x - y Nb 2 O 6 the Curie temperature could be varied between about 80 ∘ C for strontium barium niobate with x Sr = 0.61 and about 300 ∘ C for CBN with x Ca ≈ 0.20 , the lowest possible Ca content.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
