Enthalpy of formation and thermodynamic insights into yttrium doped BaZrO<sub>3</sub>

Gonçalves, Mayra D.; Maram, Pardha Saradhi; Muccillo, R.; Navrotsky, Alexandra

doi:10.1039/c4ta03487b

Cited by 54 publications

(39 citation statements)

References 76 publications

(137 reference statements)

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“…Interest has turned to materials with defect fluorite structure since their conductivity is usually intrinsic and does not require additional elements as dopants. The doping, which often involves oxides of Sr and Ba, can cause technological problems in humid atmospheres and also can influence the stability of compounds (Goncalves et al 2014). Thus finding relatively stable material with intrinsic conductivity would be beneficial.…”

Section: Figurementioning

confidence: 99%

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Mielewczyk‐Gryń

Navrotsky

2015

American Mineralogist

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High-temperature oxide melt solution calorimetry was used to investigate energetics of a series of rare earth niobates RE 3 NbO 7 . All of investigated compounds were found to be stable in enthalpy in respect to their oxides. The enthalpy of formation from oxides becomes more exothermic as the size of the RE cation increases, a trend seen previously in other RE compounds including pyrochlores, perovskites, and phosphates. For smaller RE cations the enthalpy of exchange of RE between niobates and titanates is close to zero, whereas larger RE are energetically favored in the titanate pyrochlores. Implications of the results from the geochemical and material engineering points of view are discussed.

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Section: Figurementioning

confidence: 99%

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Mielewczyk‐Gryń

Navrotsky

2015

American Mineralogist

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“…Despite the use of a high gas-pressure, a white colored deposition was observed on the quartz tube surrounding the feed rod and the seed rods, indicating the evaporation of BaO during the growth process as usually observed in zirconia-based systems [39][40][41] at high temperature. The as-grown BaZrO 3 boules were polycrystalline and mostly opaque and white colored ( Fig.…”

Section: Crystal Growth By the Optical Floating Zone Techniquementioning

confidence: 99%

Single crystal growth of BaZrO₃ from the melt at 2700 °C using optical floating zone technique and growth prospects from BaB₂O₄ flux at 1350 °C

et al. 2019

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We report the growth of BaZrO 3 single crystals by the optical floating zone technique and the investigation on its flux growth using BaB 2 O 4 as a solvent. 6-mm long colorless and transparent single crystals were obtained with a mirror furnace without the need for post-treatment annealing.Its properties are determined and compared with those of two commercial crystals grown by the tri-arc Czochralski method. The chemical composition was investigated using glow discharge mass spectrometry (GDMS) and secondary ion mass spectrometry (SIMS), which indicate minor impurities of Sr, Hf, Ca and Ti, with maximal concentrations for Sr and Hf in the range of 0.3-0.5 % at. The optical band gap determined by UV-visible spectroscopy is found to be ~4.8 eV and Page 1 of 25 CrystEngComm 2indicates the high quality of the BaZrO 3 crystals grown by the optical floating zone technique.Raman spectroscopy at ambient conditions and at low temperatures down to 4.2 K reveals a relatively sharp second-order spectrum and does not reveal any structural phase transition.

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“…DG°{3} and DG°{7} can be estimated from literature data. 18,19,40,41 The Gibbs energy can be expressed as a function of the partial pressure of CO 2 through the expressions…”

Section: And Chemical Stability Of Bzy-materialsmentioning

confidence: 99%

Effect of CO₂ Exposure on the Chemical Stability and Mechanical Properties of BaZrO₃‐Ceramics

et al. 2016

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The reactivity of BaZrO3 with CO2 has been addressed as one of the major challenges with BaZrO3-based electrolytes in proton ceramic fuel cells. Here, we present a study of the effect of CO2 exposure of BaZrO3-materials at elevated temperatures. Dense BaZr1-xYxO3-δ (x = 0, 0.05, 0.1, 0.2) and BaCe0.2Zr0.7Y0.1O2.95 ceramics were prepared by conventional sintering of powder prepared by spray pyrolysis. The Vickers indentation method was used to determine the hardness and estimate the fracture toughness of pristine materials as well as the corresponding materials exposed to CO2. Formation of BaCO3 on the surface of exposed ceramics was confirmed by X-ray diffraction and electron microcopy. The reaction resulted in formation of Ba-deficient perovskite at the exposed surface. The reaction with CO2 was most pronounced at 650 ºC compared to the other temperatures applied in the study. The reactivity was also shown to depend on the Y-content and the grain size and was most pronounced for BaZr0.9Y0.1O3-δ. The reaction with CO2 was observed to have a profound effect on the fracture toughness of the ceramics, demonstrating a depression of the mechanical stability of the materials. The results are discussed with respect to the chemical and mechanical stability of BaZrO3 materials, with particular emphasis on the composition and grain size.

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Enthalpy of formation and thermodynamic insights into yttrium doped BaZrO₃

Cited by 54 publications

References 76 publications

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Single crystal growth of BaZrO₃ from the melt at 2700 °C using optical floating zone technique and growth prospects from BaB₂O₄ flux at 1350 °C

Effect of CO₂ Exposure on the Chemical Stability and Mechanical Properties of BaZrO₃‐Ceramics

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Enthalpy of formation and thermodynamic insights into yttrium doped BaZrO3

Cited by 54 publications

References 76 publications

Enthalpies of formation of rare earth niobates, RE3NbO7

Enthalpies of formation of rare earth niobates, RE3NbO7

Single crystal growth of BaZrO3 from the melt at 2700 °C using optical floating zone technique and growth prospects from BaB2O4 flux at 1350 °C

Effect of CO2 Exposure on the Chemical Stability and Mechanical Properties of BaZrO3‐Ceramics

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Enthalpy of formation and thermodynamic insights into yttrium doped BaZrO₃

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Enthalpies of formation of rare earth niobates, RE₃NbO₇

Single crystal growth of BaZrO₃ from the melt at 2700 °C using optical floating zone technique and growth prospects from BaB₂O₄ flux at 1350 °C

Effect of CO₂ Exposure on the Chemical Stability and Mechanical Properties of BaZrO₃‐Ceramics