(382aq) Insights into Phase Control and Stabilization of Metastable ?-Phase of AMoO4 (A = Ni, Co, Ni/Co) Based Solid Solutions

Research Interests This study investigates the synthesis and phase behavior of NiMoO₄ (Nickel Molybdate) using a solid-state route, emphasizing the metastable β-phase which is reported as chemically more active than alpha phase. The β-phase, exhibits tetrahedral molybdenum coordination, but the stabilization of this phase remains challenging.

Through detailed Rietveld refinement—applied for the first time to β-NiMoO₄—this work offers quantitative insights into phase composition across a temperature range (700–1000°C). The findings reveal a temperature-dependent transformation, with more β-phase at 700°C and diminishing at higher temperatures and pure alpha phase at 1000°C. Optimized synthesis which is at 20 atomic percent more addition of MoO₃ successfully eliminated side-phase impurities such as NiO. Quenching experiments further confirmed the thermodynamic instability of the β-phase, predominantly yielding α-NiMoO₄. Additionally, cobalt doping was employed to enhance β-phase stabilization, and on doping of Cobalt almost 5 % of beta phase has been stabilized. Variable-temperature XRD provided a comprehensive understanding of phase transitions in both pristine and doped samples. This study pioneers a systematic approach to controlling the β-phase, offering potential pathways for its integration into application which is glucose sensing. The findings contribute to advancing the fundamental understanding of NiMoO₄’s phase stability and its functional optimization.