Synthesis and crystal structure of CdNd4[SiO4]3O

Sidorov, P.M.; Белоконева, Е. Л.; Fedorov, N. F.; Tunik, T. A.; Simonov, M. A.; Belov, N. V.

doi:10.1007/bf00753986

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…These results were consistent with the results of Masubuchi et al 41),54) A new question arose as follows: "Nakayama et al 33) reported an inflection point in thermal change in conductivity at around 600 K, we could not find any apparent difference on structures below and above the temperature." For results obtained at room temperature, the results on anisotropic thermal displacement of oxygen at the O4(2a) site and the rigidity of SiO 4 tetrahedra were consistent with the crystal structure analysis of Cd 2 Nd 8 (SiO 4 ) 6 O 2 by Sidrov et al 57) León-Reina et al reported a crystal-structure model of La 9.55 -(SiO 4 ) 6 O 2.32 based on XRD and NPD as a function of temperature; their model included an interstitial oxygen position. 45) In this study, the authors speculated that OH and H 2 O species might be contained in the structure to achieve charge neutrality with the different cation ratio.…”

Section: Crystal Structure Model After the Discovery Of Oxygen-ion Cosupporting

confidence: 87%

Research progress in nondoped lanthanoid silicate oxyapatites as new oxygen-ion conductors

Kobayashi

Sakka

2014

J. Ceram. Soc. Japan

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The discovery of oxygen-ion conductivity and changes in the crystal-structure model of nondoped lanthanum silicate oxyapatites are reviewed from the researches which led to the discovery to current work. The oxygen-ion conductivity of lanthanoid silicate oxyapatites was discovered by Nakayama et al., during development of new oxide lithium-ion conductors. Although samples with compositions of LiRESiO 4 (RE = La, Nd, Sm, Gd, Dy) were initially reported to be single phases with the same crystal structure, the accurate crystal structure of LiRESiO 4 was not clarified until later. The crystal structure determined from X-ray diffraction patterns of LiLnSiO 4 was revised as oxyapatite by another group. The chemical composition of the crystal phases in LiRESiO 4 was also revised to RE 10 Si 6 O 25 and/or RE 9.33 Si 6 O 24 . The discovery of oxygen-ion conductivity in these materials was confirmed when researchers noted that samples of RE 10 Si 6 O 25 , specifically, the samples without lithium, are electrically conducting. Furthermore, very high oxygen-ion conductivity in the direction parallel to c-axis was discovered after single crystals of RE 9.33 (SiO 4 ) 6 O 2 (RE = Nd, Pr, and Sm) were successfully grown. The crystal structure and defect models were also altered after the discovery of oxygen-ion conductivity. Although numerous reports related to the electrical conductivity of La 9.33+x (SiO 4 ) 6 O 2+3x/2 ceramics have appeared in the literature, clear dependences of the total conductivity on the cation nonstoichiometry (x) as well as the sintering temperature are still unclear because of large discrepancies in the reported data. Furthermore, the composition region, where the lanthanum silicate oxyapatite single phase is formed, is also still unclear because of the inconsistencies in the reported results.

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Section: Crystal Structure Model After the Discovery Of Oxygen-ion Cosupporting

confidence: 87%

Research progress in nondoped lanthanoid silicate oxyapatites as new oxygen-ion conductors

Kobayashi

Sakka

2014

J. Ceram. Soc. Japan

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“…With respect to the quasi-ternary phase diagrams including rare-earth silicates, most of the phase diagrams have not yet been solved except for Y 2 3 O using single crystal grown from solution in a melt of alkaline fluoride. 71) Size of the single crystal was from 1 to 10 mm. They succeeded to determine the space group, atomic positions, isotropic thermal displacement parameter, and anisotropic thermal displacement parameter.…”

Section: )26)mentioning

confidence: 99%

Rudimental research progress of rare-earth silicate oxyapatites: their identification as a new compound until discovery of their oxygen ion conductivity

Kobayashi

Sakka

2014

J. Ceram. Soc. Japan

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Rudimental research progress of rare-earth silicate oxyapatites: their identification as a new compound until discovery of their oxygen ion conductivity Kiyoshi KOBAYASHI³ and Yoshio SAKKA Materials Processing Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JapanRudimental research progress of oxyapatite-type rare-earth silicates is reviewed based on the published papers mainly from 1959 to 1993 that have not yet been discussed in detail. The knowledge of oxyapatite-type rare-earth silicates significantly increased during this period. Chemical compounds of rare-earth oxides and silica were discovered around 1960. Because of the complex chemical composition of the oxyapatite phase, the composition was initially considered as 2RE 2 O 3 ·3SiO 2 , which was called orthosilicate. "RE" is the rare-earth elements. Different compositions of 2RE 2 O 3 ·3SiO 2 have been proposed by crystal structure analysis based on the crystal chemistry and the leaping model. With respect to crystal structure analysis, knowledge has gradually improved step-by-step, including the implicit distinction between oxygen-stoichiometric apatite and oxygen-deficient apatite. Based on the published work, the rare-earth silicate oxyapatites are considered to have an apatite-like structure. Initially, application research focused on the optical properties of oxyapatite because rare-earth metals were constituent elements of the crystals, and on the use of oxyapatite as a stabilizer of unwanted radioactive waste produced in nuclear power reactors because oxyapatites can dissolve the actinide elements.

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“…A huge number of rare-earth ortho -silicates can be derived from the structure of the mineral fluoro-apatite , Ca 5 (PO 4 ) 3 F, − (Table ). As can be seen from the scheme in Figure , the structure is retained when the SiO 4 4- ion is placed for PO 4 3- and F - is substituted for O 2- .…”

Section: Ortho-silicatesmentioning

confidence: 99%

Inorganic Lanthanide Compounds with Complex Anions

2002

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Mathias S. Wickleder was born in Bergen, Germany, in 1965. He received his Dr. rer. nat. degree at the University of Hannover under the direction of Professor G. Meyer in 1994. Thereafter he joined the group of Professor H. U. Gu ¨del, Bern, Switzerland, as a postdoctoral fellow for two years. In 2000 he finished his Habilitation at the Institute for Inorganic Chemistry in Cologne. His research interests include the structural chemistry and thermal behavior of rare-earth and transition-metal compounds with complex anions.

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Synthesis and crystal structure of CdNd4[SiO4]3O

Cited by 6 publications

References 1 publication

Research progress in nondoped lanthanoid silicate oxyapatites as new oxygen-ion conductors

Research progress in nondoped lanthanoid silicate oxyapatites as new oxygen-ion conductors

Rudimental research progress of rare-earth silicate oxyapatites: their identification as a new compound until discovery of their oxygen ion conductivity

Inorganic Lanthanide Compounds with Complex Anions

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