Dielectric properties of Ln(Mg_1/2Ti_1/2)O₃ as substrates for high-T_c superconductor thin films

Abstract

Ln(Mg1/2Ti1/2)O3 (Ln = Dy, La, Nd, Pr, Sm, Y) compositions have been prepared, and their pertinent properties for use as thin film substrates for YBa2Cu3Ox (YBCO) were measured. X-ray diffraction shows that Ln(Mg1/2Ti1/2)O3 compositions have noncubic symmetry and the GdFeO3-type structure. Dielectric constant measurements revealed values between 22 and 27, which are larger than those of the LnAlO3 family. Quality factor (=1/ tan δ) of the ceramic specimens measured at room temperature was larger than 3000 at 10 GHz. Among the compounds, La(Mg1/2Ti1/2)O3 exhibited the highest dielectric constant and the lowest dielectric loss. Chemical reaction was observed between Ln(Mg1/2Ti1/2)O3 (Ln = Dy, Sm, Y) and YBCO after annealing a 1 : 1 mixture at 950 °C. Considering dielectric and physical properties, La(Mg1/2Ti1/2)O3 and Sm(Mg1/2Ti1/2)O3 were determined to be suitable substrates for YBCO thin film used in microwave applications.

Microwave dielectric properties of Mg4Nb2O9 ceramics produced by hydrothermal synthesis

“…XRD analysis of the dielectric ceramics and electrode powder mixture sintered at the desired temperature is considered an acceptable way to analyze the interface reaction [15]. This method is widely used for the investigation of any reaction between dielectrics and electrode materials used in multilayer chip capacitors.…”

Ferroelectric-Dielectric Solid Solution and Composites for Tunable Microwave Application

“…(Qf=59000GHz) (Cho et al 1997). For Nd(Mg 0.5 Ti 0.5 )O 3 , the corresponding value is 26, -49 ppmK -1 and 36900GHz, respectively (Cho et al 1999). XRD analysis showed that they can form solid solution with Ba 0.6 Sr 0.4 TiO 3 (Fig.…”

Microstructure and microwave dielectric properties of xSm(Mg0.5Ti0.5)O3–(1 − x)Ca0.8Sr0.2TiO3 ceramics

“…Among them, Sm(Mg 0.5 Ti 0.5 )O 3 has a moderate dielectric constant (e r * 25), a high quality factor (Q 9 f * 65,500 GHz) and a negative temperature coefficient of resonance frequency (s f * -26 ppm/°C) [11], which limits its practical applications. In order to compensate the s f of Sm(Mg 0.5 Ti 0.5 )O 3 , CaTiO 3 was added to form (1 -x)CaTiO 3 -xSm(Mg 0.5 Ti 0.5 )O 3 solid solution, but that compound did not show ideal dielectric properties because of phase transformation [12].…”