A Novel, Simple and Highly Efficient Route to Obtain PrBaMn2O5+δ Double Perovskite: Mechanochemical Synthesis

Abstract

In this work, a mechanochemical route was proposed for the synthesis of the PrBaMn2O5+δ (PMBO) double layered perovskite phase. The mechanochemical reaction between Pr6O11, BaO2, and MnO powders with cationic stoichiometric ratios of 1/1/2 for Pr/Ba/Mn was performed using high-energy milling conditions in air. After 150 min of milling, a new phase with perovskite structure and cubic symmetry consistent with the A-site disordered Pr0.5Ba0.5MnO3 phase was formed. When this new phase was subsequently annealed at a high temperature in an inert Ar atmosphere, the layered PrBaMn2O5+δ phase was obtained without needing to use a reducing atmosphere. At 1100 °C, the fully reduced layered PrBaMn2O5 phase was achieved. A weight gain was observed in the 200–300 °C temperature range when this fully reduced phase was annealed in air, which was consistent with the transformation into the fully oxidized PrBaMn2O6 phase. The microstructural characterization by SEM, TEM, and HRTEM ascertained the formation of the intended PrBaMn2O5+δ phase. Electrical characterization shows very high electrical conductivity of layered PBMO in a reducing atmosphere and suitable in an oxidizing atmosphere, becoming, therefore, excellent candidates as solid oxide fuel cell (SOFC electrodes).

Solvent-Free Mechanochemical Synthesis and Characterization of Nickel Tellurides with Various Stoichiometries: NiTe, NiTe2 and Ni2Te3

“…The samples are formed irregularly shaped agglomerates ranging from several hundreds of nm to micron-sized clusters. Most of the agglomerates are formed from smaller rounded particles, which is characteristic of powders prepared by dry mechanochemical reactions [ 37 ], while some clear straight edges of freshly crushed grains can also be observed, especially in Figure 4 a. The results of EDX analysis (typical pattern shown in Figure 4 d) confirm the presence of Ni and Te in the sample and the absence of impurities.…”

“…The mechanochemical method, also known as mechanical alloying, is a convenient solid-state processing technique in which the precursor powders are exposed to repeated welding, fracturing, and re-welding in a high energy ball mill. The method has been developed in the 1970s for the fabrication of nickel- and iron-base superalloys for applications in the aerospace industry [ 32 , 33 ] and is nowadays widely used in the processing of advanced materials like alloys [ 34 ], bimetallic nanocatalysts [ 35 ], oxide materials [ 36 , 37 ], carbon-based materials [ 38 , 39 , 40 ], etc. The first reports of mechanochemical synthesis of metal chalcogenides date back to the 1990s, and since then, a number of nanosized sulfides, selenides, and tellurides have been prepared using this method.…”

Layered Oxygen-Deficient Double Perovskites as Promising Cathode Materials for Solid Oxide Fuel Cells

“…Layered manganites of barium and REEs (for example, PrBaMn 2 O 5+δ ) have been considered as possible electrode materials both for A–SOFCs and S–SOFCs, as well as for SOECs cathodes [ 199 , 200 , 201 ]. The high thermal stability of Fe-doped PrBaMn 2– x Fe x O 6–δ perovskites both in oxidizing and reducing atmospheres and the moderate TEC values make these phases good candidates for electrochemical applications [ 200 ].…”

DC 4-Point Measurement for Total Electrical Conductivity of SOFC Cathode Material

“…The obtained data may not be consistent for various research teams owing to differences in the measurement conditions, etc. Additionally, it is known that the conductivity of the materials is affected by the fabrication method [13,14]. Different fabrication methods result in different grain sizes that affect the contributions of the grains and grain boundaries [13], as well as in the presence or absence of undesirable secondary phases [14].…”

“…Additionally, it is known that the conductivity of the materials is affected by the fabrication method [13,14]. Different fabrication methods result in different grain sizes that affect the contributions of the grains and grain boundaries [13], as well as in the presence or absence of undesirable secondary phases [14]. If the conductivity measurement method using the DC 4 point-probe method for conductive ceramics, including SOFC cathode materials, is standardized, data reliability and compatibility between research groups can be improved.…”