Structure and dielectric properties of rf sputtered Bi2O3–MgO–Nb2O5 pyrochlore thin films

• Published in: Journal of alloys and compounds 2014-07, Vol.600, p.107-110
• Main Authors: Gao, Libin, Jiang, Shuwen, Li, Ruguan, Li, Yanrong
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cubic pyrochlore; Dielectric loss and relaxation; Dielectric properties; Dielectric properties of solids and liquids; Dielectric thin films; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Permittivity (dielectric function); Physics; Sputtering; Tunability
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.02.046

•The cubic pyrochlore structure accommodates a wide range of chemical substituent.•Dielectric constant of BMN thin films increased with Mg2+ ions concentration.•Dielectric loss of BMN thin films changed little with Mg2+ ions concentration.•Dielectric tunability of BMN thin films showed Mg2+ ions concentration dependence. The cubic pyrochlore Bi1.5MgNNb2.5−NO8.5−1.5N (BMN) thin films with various compositions were deposited on Pt coated sapphire substrates by rf magnetron sputtering. Crystal structures of the BMN thin films by X-ray diffraction exhibited nearly pure cubic pyrochlore phase in a wide range of chemical substituents. The dielectric properties were systematically studied and discussed. The dielectric constant was found to increase with increasing Mg2+ content, while the dielectric loss changed little with the Mg2+ concentration and remained in a low level of ∼0.006. The BMN thin films with a composition of Bi1.5Mg1.0Nb1.5O7 demonstrated a tunability of 20% at applied bias filed of 1.0MV/cm. The insufficient Mg2+ content decreased the tunability of the BMN thin films. However, the BMN thin films with excess Mg2+ content also did not exhibit enhanced tunable performance. These results indicated that the appropriate Mg2+ content and stoichiometric composition were of significance for improving the tunability of BMN thin films.