Humidity-dependent dielectric and electrical behavior of strontium iron vanadate ceramics

Document Type

Article

Publication Date

2026

Abstract

Metal-oxide ceramics with perovskite-related structures offer tunable properties for sensing applications. The strontium iron vanadate ceramic system remains underexplored for humidity sensing despite theoretical interest in Sr2FeVO6-type compositions. This study presents sol–gel synthesis of a strontium iron vanadate ceramic at 900 °C and its characterization as an impedance-type humidity sensor. XRD revealed a multi-phase composition with a perovskite-related Ia3̄d superstructure (a = 10.040 Å, 20 superstructure reflections systematically absent in Pm3̄m) and Sr-vanadate phases. FTIR confirmed a hydrophilic metal–oxygen framework with BO6 octahedral vibrations characteristic of perovskite-related structures. SEM showed ∼1.6 µm grains with inter-particle porosity; DLS showed ∼460 nm agglomerates. The zeta potential was −15 mV, indicating surface hydroxylation. Impedance spectroscopy (50 Hz–5 MHz, 11–97% RH) demonstrated 621% per %RH sensitivity at 50 Hz with two clearly separated conduction regimes: localized hopping mechanisms dominating at low RH and long-range proton transport occurring through continuous water pathways at elevated RH. The dielectric permittivity increased to approximately 106–107 at low frequencies, accompanied by a more conduction-related loss behavior at higher humidity, while the AC conductivity rose by nearly four orders of magnitude. This work reports the humidity sensing properties of a sol–gel-derived strontium iron vanadate ceramic with perovskite-related contributions and provides mechanistic insight into two-stage conduction behavior.

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