TY - JOUR
T1 - Conductivity, structure, and thermodynamics of Y2Ti2O7-Y3NbO7solid solutions
AU - Winiarz, Piotr
AU - Mielewczyk-Gryń, Aleksandra
AU - Lilova, Kristina
AU - Wachowski, Sebastian
AU - Subramani, Tamilarasan
AU - Abramchuk, Mykola
AU - Dzik, Ewa
AU - Navrotsky, Alexandra
AU - Gazda, Maria
N1 - Funding Information:
This work was partially supported by project no. 2016/23/B/ ST5/02137 founded by the National Science Centre, Poland. The calorimetric studies were supported by the U.S. Department of Energy Office of Basic Energy Science, grant DE-FG02-03ER46053.
Publisher Copyright:
© The Royal Society of Chemistry.
PY - 2020/8/21
Y1 - 2020/8/21
N2 - The defect fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via a solid state synthesis route. The resulting stoichiometry of the oxides is Y2+xTi2-2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase; however, for those with a predominant fluorite phase, a small amount of additional pyrochlore phase was detected. The volume of the solid solution unit cells linearly increases with increase in yttrium niobate content. The water uptake increases with (x) and the protonic defect concentration reaches almost 4.5 × 10-3 mol mol-1 at 300 °C. The calculated enthalpy of formation from oxides suggests strong stability for all of the compositions, with the values of enthalpy ranging from -84.6 to -114.3 kJ mol-1. The total conductivity does not have a visible dependence on Y3NbO7 content. For each compound, the total conductivity is higher in wet air. Interestingly, for samples where x < 0.5, the ratio of conductivity in hydrogen to air increases with increasing temperature, while for x > 0.5, the trend is the opposite.
AB - The defect fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via a solid state synthesis route. The resulting stoichiometry of the oxides is Y2+xTi2-2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase; however, for those with a predominant fluorite phase, a small amount of additional pyrochlore phase was detected. The volume of the solid solution unit cells linearly increases with increase in yttrium niobate content. The water uptake increases with (x) and the protonic defect concentration reaches almost 4.5 × 10-3 mol mol-1 at 300 °C. The calculated enthalpy of formation from oxides suggests strong stability for all of the compositions, with the values of enthalpy ranging from -84.6 to -114.3 kJ mol-1. The total conductivity does not have a visible dependence on Y3NbO7 content. For each compound, the total conductivity is higher in wet air. Interestingly, for samples where x < 0.5, the ratio of conductivity in hydrogen to air increases with increasing temperature, while for x > 0.5, the trend is the opposite.
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U2 - 10.1039/d0dt02156c
DO - 10.1039/d0dt02156c
M3 - Article
C2 - 32705110
AN - SCOPUS:85089358986
SN - 1477-9226
VL - 49
SP - 10839
EP - 10850
JO - Dalton Transactions
JF - Dalton Transactions
IS - 31
ER -