Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 1 de 1
Filtrar
Mais filtros










Base de dados
Assunto principal
Intervalo de ano de publicação
1.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 72(Pt 5): 744-752, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27698316

RESUMO

Vesuvianite containing 5.85 wt% TiO2 from an Alpine-cleft-type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, Pakistan, has been investigated by means of electron microprobe analyses, gas-chromatographic analysis of H2O, X-ray powder diffraction, single-crystal X-ray structure refinement, 27Al NMR, 57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are: a = 15.5326 (2), c = 11.8040 (2) Å, space group P4/nnc. The structure was refined to final R1 = 0.031, wR2 = 0.057 for 11247 I > 2σ(I). A general crystal-chemical formula of studied sample can be written as follows (Z = 2): [8-9](Ca17.1Na0.9) [8]Ca1.0[5](Fe2+0.44Fe3+0.34Mg0.22) [6](Al3.59Mg0.41) [6](Al4.03Ti2.20Fe3+1.37Fe2+0.40) (Si18O68) [(OH)5.84O2.83F1.33]. The octahedral site Y2 is Al-dominant and does not contain transition elements. Another octahedral site Y3 is also Al-dominant and contains Fe2+, Fe3+ and Ti. The site Y1 is split into Y1a and Y1b predominantly occupied by Fe2+ and Fe3+, respectively. The role of the Y1 site in the diversity of vesuvianite-group minerals is discussed.


Assuntos
Minerais/química , Cromatografia Gasosa , Cristalografia por Raios X , Ferro/química , Espectroscopia de Ressonância Magnética , Minerais/análise , Paquistão , Pós/química , Espectrofotometria Infravermelho , Espectroscopia de Mossbauer , Titânio/química , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...