Proton conducting electrolyte Ba3Ca1.18Nb1.72Y0.1O9-δ for hydrogen separation and fuel cell: Study on phase composition, microstructure, and electrical properties

The complex perovskite type proton-conducting materials Ba₃Ca_1.18Nb_1.82O_9-δ (BCN18) and Ba₃Ca_1.18Nb_1.72Y_0.1O_9-δ (BCNY) were fabricated via a solid-state synthesis route. Structural characterization of both compounds was performed through X-ray diffraction analysis (XRD). The microstructure of BCN18 and BCNY were carried out by scanning electron microscopy (SEM). The electrochemical properties were evaluated via alternating current impedance spectroscopy (EIS). The XRD patterns confirmed the successful synthesis of BCN18 and BCNY. Microstructural analysis through SEM revealed compact morphology for both materials. Grain boundary characteristics were examined using distribution of relaxation time (DRT) method, demonstrating that BCNY possesses significantly reduced grain boundary resistance compared to BCN18. The conductivities of BCN18 and BCNY were 2.6 × 10⁻³ S cm⁻¹ and 4.64 × 10⁻³ S cm⁻¹ at 800 °C. BCNY demonstrated a marginally elevated proton transference number relative to BCN18 under identical evaluation conditions. In the hydrogen separation measurement, the hydrogen permeation flux of BCNY was higher than that of BCN18. This study provides important references for developing high-performance proton-conducting electrolytes in hydrogen separation and fuel cell applications.