High temperature crystallographic and thermodynamic investigations on synthetic calzirtite (Ca2Zr5Ti2O16)

Jafar, Mohsin; Phapale, S.; Achary, S.N.; Mishra, R.; Tyagi, A. K.

doi:10.1016/j.jallcom.2016.04.252

Cited by 9 publications

(12 citation statements)

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“…In a reducing atmosphere, 29‐32 Ca 2 Zr 5 Ti 2 O 16 (C1) could decompose into CaZrO 3 , ZrO 2 , and TiO 2 (Equation ), and CaZrTi 2 O 7 (C2) could decompose into CaZrO 3 and TiO 2 (Equation ). However, Ti easily diffused into the composites and reacted with TiO 2 to form Ti 2 O according to Equation () 33 .…”

Section: Resultsmentioning

confidence: 99%

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Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Lin

2021

Int J Applied Ceramic Tech

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Various proportions of ZrO2/CaTiO3 powders were mixed and hot pressed at 1500°C/30 min for Ti casting. The hot‐pressed ZrO2/CaTiO3 composites were reacted with pure Ti at 1700°C/10 min in Ar. The interfacial reaction between Ti and ZrO2/CaTiO3 composites was investigated through X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy. The ZrO2/CaTiO3 composites with less than 10 vol.%, CaTiO3, and a minor amount of residual TiO2 were found. When the content of ZrO2 was increased to larger than 10 vol.%, two Ca2Zr5Ti2O16 and CaZrTi2O7 phases appeared in the composites. The amount of CaTiO3 and CaZrTi2O7 in the composites gradually decreased as the amount of ZrO2 increased. When Ti came in contact with ZrO2/CaTiO3 composites with less than 10 vol.% ZrO2, the resulting eutectic reaction produced a liquid phase and induced melting. When ZrO2 was increased to more than 30 vol.% in the composites, Ca2Zr5Ti2O16 and CaZrTi2O7 changed completely to CaZrO3, Ti2O, CaO, and ZrO2. With more than 30 vol.% ZrO2, no other reaction phases occurred in the Ti side after contact with the ZrO2/CaTiO3 composites, which is conducive for producing ceramic composites for Ti casting applications.

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Section: Resultsmentioning

confidence: 99%

“…In a reducing atmosphere, [29][30][31][32] 5). However, Ti easily diffused into the composites and reacted with TiO 2 to form Ti 2 O according to Equation (6).…”

Section: Methodsmentioning

confidence: 99%

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Lin

2021

Int J Applied Ceramic Tech

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“…The analysis of the reflection conditions unequivocally led to the choice of the space group I 4 1 / acd . Given the close similarity in terms of unit-cell dimensions and crystal symmetry, the crystal structure was refined starting from the atomic coordinates of calzirtite, ideally Ca 2 Zr 5 Ti 2 O 16 (Rossel 1982; Sinclair et al , 1986; Rastsvetaeva et al , 1995; Jafar et al , 2016).…”

Section: X-ray Diffraction Data and Refinementmentioning

confidence: 99%

Crystal structure and composition of hiärneite, Ca₂Zr₄Mn³⁺SbTiO₁₆, and constitution of the calzirtite group

Holtstam

Bindi

2022

MinMag

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The crystal structure of hiärneite has been refined from single-crystal X-ray diffraction data (λ = 0.71073 Å) on type material from Långban, Värmland, Sweden. The refinement converged to R 1 = 0.046 based on 1073 reflections with F 2 > 4σ(F 2 ). The tetragonal unit cell, space group I4 1 /acd, has the parameters a = 15.2344(6) Å and c = 10.0891(6) Å with Z = 8. The mineral is isostructural with calzirtite, ideally Ca 2 Zr 5 Ti 2 O 16 , with a fluorite-derivated structural topology. In hiärneite, Mn 3+ is ordered at a 4-to 8-fold coordinated site (with a distorted polyhedral coordination figure), without the atom splitting encountered at the corresponding Zr-dominated site of calzirtite. The end-member formula for hiärneite is established as Ca 2 Zr 4 Mn 3+ SbTiO 16 . The calzirtite group, with calzirtite, hiärneite and tazerhanite (cubic ZrO 2-x ), has been approved by IMA-CNMNC.

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“…Its synthetic counterpart can be synthesized in the laboratory by means of solid-state reactions. Two different polymorphs are known: an orthorhombic phase stable at ambient conditions ( Pbca ) and a tetragonal high-temperature phase ( I 4 1 / acd ) . Both polymorphs are very similar and have a fluorite-related superstructure arrangement.…”

Section: Introductionmentioning

confidence: 99%

“…In the figure it can be seen that it consists of a network CaO 8 , TiO 6 , and ZrO 7 polyhedra which are linked by sharing edges to form the three-dimensional framework. A comprehensive description of the crystal structure of calzirtite polymorphs can be found in the literature . One of the most interesting properties of calzirtite is its capacity to host radioactive elements by elevated concentrations, for instance, up to 17.9 wt % UO 2 and 20.0 wt % ThO 2 .…”

Section: Introductionmentioning

confidence: 99%

High-Pressure X-ray Diffraction Study of Orthorhombic Ca₂Zr₅Ti₂O₁₆

et al. 2023

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The orthorhombic polymorph of Ca 2 Zr 5 Ti 2 O 16 (space group Pbca) has been studied by powder X-ray diffraction under high pressures up to 30 GPa using synchrotron radiation. We have found evidence of a structural phase transition at 12−13 GPa. The phase transition causes an enhancement of the crystal symmetry. The high-pressure phase is tetragonal, being described by space group I4 1 /acd. The space groups of the high-and lowpressure phases have a group/subgroup relationship. However, the phase transition is accompanied by a discontinuous change in the unit-cell volume, indicating that the phase transition can be classified as first order. We have also performed density functional theory calculations. These simulations support the occurrence of the orthorhombic-to-tetragonal transition. The pressure−volume equation of state and axial compressibilities have been determined for both polymorphs. The results are compared with previous studies in related oxides.

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High temperature crystallographic and thermodynamic investigations on synthetic calzirtite (Ca2Zr5Ti2O16)

Cited by 9 publications

References 10 publications

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Crystal structure and composition of hiärneite, Ca₂Zr₄Mn³⁺SbTiO₁₆, and constitution of the calzirtite group

High-Pressure X-ray Diffraction Study of Orthorhombic Ca₂Zr₅Ti₂O₁₆

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High temperature crystallographic and thermodynamic investigations on synthetic calzirtite (Ca2Zr5Ti2O16)

Cited by 9 publications

References 10 publications

Microstructural evolution and interfacial reactions between Ti and ZrO2/CaTiO3 composites

Microstructural evolution and interfacial reactions between Ti and ZrO2/CaTiO3 composites

Crystal structure and composition of hiärneite, Ca2Zr4Mn3+SbTiO16, and constitution of the calzirtite group

High-Pressure X-ray Diffraction Study of Orthorhombic Ca2Zr5Ti2O16

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Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Microstructural evolution and interfacial reactions between Ti and ZrO₂/CaTiO₃ composites

Crystal structure and composition of hiärneite, Ca₂Zr₄Mn³⁺SbTiO₁₆, and constitution of the calzirtite group

High-Pressure X-ray Diffraction Study of Orthorhombic Ca₂Zr₅Ti₂O₁₆