English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

The crystal chemistry of Ti-rich ferriallanite-(Ce) in syenites from Cape Ashizuri, Shikoku Island, Japan, was studied using electron microprobe analysis (EMPA) and single-crystal X‑ray diffraction methods. Our specimens (AS001 and AS304) are characterized by high-Ti (-3.6 wt% TiO 2 ) and Fe contents (-21.3 wt% FeO*; Fe 2+ /total Fe = 0.6-0.7). Structure refinements of two ferriallanite-(Ce) crystals converged to R1 = 1.50-1.57%. In both specimens, the dominant cations at A1, A2, and M3 are Ca, Ce, and Fe 2+ , respectively. However, depending on Ti assignment, two different schemes of the cation distributions at M1 and M2 can be considered: (1) (Fe 0.72 Ti 0.23 Al 0.05 )M1(Al 0.82 Fe 3+  0.18 )M2 and (2) (Fe 0.90 Al 0.10 )M1(Al 0.77 Ti 0.23 )M2 for AS001, and (1) (Fe 0.65 Ti 0.29 Al 0.06 )M1(Al 0.89 Fe 3+  0.11 )M2 and (2) (Fe 0.76 Ti 0.13 Al 0.11 )M1(Al 0.84 Ti 0.16 )M2 for AS304. The Si 2 O 7  group is compressed along Sil-O9-Si2 direction because of the expansions of the M1O6 and M3O6 octahedra due to substitution of large octahedral cations for Al. This compression is monitored by the atom position of O9 that shifts away from the cation at A1 decreasing the Si1-O9-Si2 angle. In allanite-subgroup minerals, the A1-O9 distance is longer and the bridging angle is smaller than those of clinozoisite-subgroup minerals. Although the A1 polyhedron is generally described as a ninefold-coordinated site, it is appropriately described as sevenfold-coordinated in Ti-rich allanite-(Ce) because of the lengthened A1-O9 (×2) distance. The cation substitutions at M1 and M3 indirectly affect the topology of the A1 polyhedron.

Crystal chemistry of Ti-rich ferriallanite-(Ce) from Cape Ashizuri, Shikoku Island, Japan