C.C. KhawP.Y. TanK.B. TanK.Y. ChanH.C. Ananda MurthyR. BalachandranS.K. ChenM.M.A. KechikO.J. LeeM. Lu2025-10-152025-10-152025-0410.1016/j.jics.2025.101637https://dspace-cris.utar.edu.my/handle/123456789/11491This study examined the impact of zinc (Zn), cadmium (Cd) and nickel (Ni) transition metals on the formation, structure and dielectric properties of bismuth magnesium tantalate (BMT) pyrochlores. A one-to-one substitution of Mg2+ with Zn2+, Cd2+ and Ni2+ in BMT pyrochlore was proposed, with Zn2+ (0.74 & Aring;) and Ni2+ (0.69 & Aring;) substituting the 6-coordinated B-site Mg2+ (0.72 & Aring;), while Cd2+ (1.10 & Aring;), possessing a similar ionic radius to Bi3+ (1.17 & Aring;), replaced Mg2+ (0.90 & Aring;) at the 8-coordinated A-site. The resulting doped BMT pyrochlore solid solutions adhered to the formulas: (Bi-3.Mg-5(0).(5))(Mg-1.3-xZnxTa2.(7))O-13.(8) (0 <= x <= 0.6), (Bi-3.Mg-5(0).(5))(Mg-1.3-xNixTa2.(7))O-13.(8) (0 <= x <= 0.1) and (Bi-3.Mg-5(0).Cd-5-x(x))(Mg-1.Ta-3(2).(7))O-13.(8) (0 <= x <= 0.1). X-ray diffraction (XRD) confirmed their phase purity, with lattice parameters ranging from 10.5515 (10) to 10.6312 (21) & Aring;. Notably, grain size remained consistent (1.3-22.4 mu m) across these modified BMT pyrochlores, exhibiting relative densities >= 90 % of the theoretical value. Scherrer and Williamson-Hall analyses indicated crystallite sizes within the 31-68 nm range. Furthermore, thermal stability was confirmed over similar to 30-1000 degrees C due to the absence of thermal events. The Ni-doped BMT pyrochlore (x = 0.1) demonstrated enhanced conductivity (activation energy, E-a = 1.38 eV) compared to the undoped material (E-a = 1.47 eV). Conversely, Zn- and Cd-doped BMT pyrochlores showed reduced conductivity (E-a approximate to 1.53 eV and 1.51 eV, respectively) with increasing dopant concentration. Specifically, Zn-doped (x = 0.6) and Cd-doped (x = 0.1) BMT exhibited favourable dielectric properties: moderately high dielectric constants (epsilon ' approximate to 80), low dielectric loss (tan delta approximate to 2 x 10(-3)) and a low temperature coefficient of dielectric constant (TC epsilon' approximate to -200 to -240 ppm/degrees C), making them suitable for ceramic capacitor applications.enTantalatesPyrochloresDielectric propertiesCeramic capacitorELECTRICAL-PROPERTIESjournal-article