Crystal chemistry of kimzeyite from Anguillara, Mts. Sabatini, Italy

Schingaro, Emanuela; Scordari, Fernando; Capitanio, Flavio; Parodi, Giancarlo; Smith, David; Mottana, Annibale

doi:10.1127/0935-1221/2001/0013-0749

Cited by 34 publications

(34 citation statements)

References 16 publications

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“…In the general garnet structure X 3 [8] Y 2 [6] Z 3 [4] O 12 the ZO 4 tetrahedra (Z = Al 3+ , Fe 3+ , Si 4+ ) are linked by Y-cation octahedra (Y = Zr 2+ , Y 3+ , Ti 4+ , Fe 2+ ), while the larger divalent X-cations (X = Ca 2+ , Mg 2+ ) are located on the dodecahedral X-site in the center of the island silicate framework. As expressed by the so-called kimzeyite-type substitution mechanism 17 Zr 4+ (Y) + Me 3+ (Z) ↔ Si 4+ (Z) + Me 3+ (Y) (Me 3+ = Al, Fe), a high Zr 4+ -level garnet requires cation distribution over the octahedrally coordinated Y-site and the tetrahedral Z-site. A similar cation substitution mechanism involves the Ti 4+ sites.…”

Section: Discussionmentioning

confidence: 99%

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Braue

Mechnich

2011

J. Am. Ceram. Soc.

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An in-service high-pressure turbine blade with a columnar, Y 2 O 3 -stabilized ZrO 2 (YSZ) thermal barrier coating (TBC) fabricated by electron-beam physical vapor deposition was investigated to access the TBC hot corrosion mechanisms during turbine operation. The TBC exhibits a throughthickness pore filling with anhydrite-type CaSO 4 . Chemical analysis of the CMAS-type particle deposits reveals relatively low SiO 2 but high CaO contents and substantial amounts of Fe 2 O 3 and TiO 2 . The hot corrosion scenario observed at the YSZ column tips involves newly formed CaZrO 3 and the garnet-type phase Ca 3 (Zr,Mg,Ti) 2 (Fe,Al,Si) 3 O 12 , also known as the mineral kimzeyite. The phase relationships were confirmed in laboratory experiments. CaSO 4 as well as the particle deposits prove to be effective solvents for YSZ introducing distinct solid-state reactions. The results support the idea of a dual YSZ hot corrosion process. A first stage controlled by a SiO 2 -free Ca-source, most likely primary CaSO 4 produces a thin CaZrO 3 layer. A second, CMAS-type stage providing high concentrations of Fe 2 O 3 , TiO 2 , and SiO 2 favors the formation of kimzeyite. The melting temperature of kimzeyite presumably defines a thermal operation limit for YSZ-based TBCs.

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Section: Discussionmentioning

confidence: 99%

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Braue

Mechnich

2011

J. Am. Ceram. Soc.

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“…Nonsilicate minerals with a garnet-type structure are also known: berzeliite [(Na, Ca 2 )Mn 2 As 3 O 12 ] and cryolithionite [Na 3 Al 2 Li 3 F 12 ]. Despite the diversity of natural garnets, the U and Th contents in these minerals do not exceed fractions of a percent and the REE contents, a few percent (Schingaro et al, 2001). However, in some cases, garnet is associated with minerals rich in these elements: monazite, xenotime, thorite, etc.…”

Section: Ferrigarnetmentioning

confidence: 99%

Natural and artificial minerals as matrices for immobilization of actinides

et al. 2007

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The possibility of insulation of long-lived actinides for the entire period of their potential hazard, i.e., over a virtually infinite time, is the crucial problem in safe disposal of high-level radioactive wastes (HLW). The reality of such a possibility is corroborated by the study of natural radioactive minerals that firmly retain U, Th, and REE, which are close in geochemical properties to transuranic actinides, for millions of years despite the effects of groundwater. The natural analogues of actinide HLW matrices are minerals where U, Th, and REE are contained as major elements or isomorphic admixtures. The study of these minerals is helpful for synthesis of durable artificial forms of wastes that ensure reliable insulation of HLW up to the complete decay of actinides independently of such engineering barriers of underground repositories as containers and bentonite buffers. The main requirements on confinement matrices include a high isomorphic capacity with respect to actinides and other HLW components, chemical and radiation stability, and technological feasibility of their industrial production. The natural and artificial minerals-uraninite, monazite, zirconolite, pyrochlore, britholite, garnet, and murataitecharacterized in this paper may serve as a basis for efficient matrices for immobilization of actinide wastes.

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“…Kimzeyite [1][2][3], a natural mineral with the simplified formulation Ca 3 Zr 2 FeAlSiO 12 , has previously been examined by neutron diffraction, Mössbauer spectroscopy and electron channeling, using HAREXCS [1], determining the structure and ordering within the cationic sub-lattice. This work was extended to include modified compositions based on Zr and Hf, such as Ca 3 Zr 2 FeAlSiO 12 and Ca 3 Zr 2 Fe 2 SiO 12 .…”

Section: Introductionmentioning

confidence: 99%

Radiation effects in Zr and Hf containing garnets

Whittle

Blackford

Smith

et al. 2015

Journal of Nuclear Materials

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a b s t r a c tGarnets have been considered as host phases for the safe immobilisation of high-level nuclear waste, as they have been shown to accommodate a wide range of elements across three different cation sites, such as Ca, Y, Mn on the a-site, Fe, Al, U, Zr, and Ti on the b-site, and Si, Fe, Al on the c-site. Garnets, due to their ability to have variable composition, make ideal model materials for the examination of radiation damage and recovery in nuclear materials, including as potential waste forms. Kimzeyite, Ca 3 Zr 2 FeAlSiO 12 , has been shown naturally to contain up to 30 wt% Zr, and has previously been examined to elucidate both the structure and ordering within the lattice. This study examines the effects of radiation damage and recovery using in-situ ion beam irradiation with 1 MeV Kr ions at the IVEM-TANDEM facility, Argonne National Laboratory. The complementary Hf containing system Ca 3 Hf 2 FeAlSiO 12 was also examined, and found to have a different response to irradiation damage. A sample of irradiated Ca 3 Zr 2 FeAlSiO 12 , at 1000 K, was characterised using aberration corrected (S)TEM and found to contain discreet, nano-sized, crystalline Fe rich particles, indicating a competing process during recovery is occurring.

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Crystal chemistry of kimzeyite from Anguillara, Mts. Sabatini, Italy

Cited by 34 publications

References 16 publications

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Natural and artificial minerals as matrices for immobilization of actinides

Radiation effects in Zr and Hf containing garnets

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Crystal chemistry of kimzeyite from Anguillara, Mts. Sabatini, Italy

Cited by 34 publications

References 16 publications

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO4 and Fe, Ti‐Rich CMAS‐Type Deposits

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO4 and Fe, Ti‐Rich CMAS‐Type Deposits

Natural and artificial minerals as matrices for immobilization of actinides

Radiation effects in Zr and Hf containing garnets

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Product

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Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits