Precision estimates of interatomic distances using site occupancies, ionization potentials and polarizability in Pbnm silicate olivines

Abstract

All interatomic distances [D(calc.)j] in

Spectroscopic characterization of chromium (IV, V, VI) in Cr:Li2MSiO4 (M=Mg,Zn)

“…33 In Cr IV :Li 2 MSiO 4 , each oxygen surrounding the Si(Cr IV ) site is also linked to one M cation and two Li ions. 11 1.56, 44 one can expect a Cr IV -oxygen bond of higher ionicity and therefore a higher B value and a lower Dq/B value than for the two studied compounds. It was already mentioned, earlier in this article, that Cr IV :LiAlO 2 also exhibits a rather long fluorescence lifetime, although shorter than for Cr IV :Li 2 MSiO 4 .…”

“…,25 The average electronegativity S ͑in Sanderson scale44 ͒ of the cations linked to the Cr IV -oxygen tetrahedron is Sϭ1.01 for Li 2 MgSiO 4 and Sϭ1.49 for Li 2 ZnSiO 4 . It follows that the electronegativity difference between these cations and oxygen (Sϭ5.21) is larger for Li 2 MgSiO 4 , their bonds are more ionic and consequently ͑bonds competition͒ the Cr IV -oxygen bond is expected to be more covalent44 in Li 2 MgSiO 4 and the B parameter smaller.…”

“…It follows that the electronegativity difference between these cations and oxygen (Sϭ5.21) is larger for Li 2 MgSiO 4 , their bonds are more ionic and consequently ͑bonds competition͒ the Cr IV -oxygen bond is expected to be more covalent44 in Li 2 MgSiO 4 and the B parameter smaller. This could explain why Dq/B, for similar values of Dq, is larger for Li 2 MgSiO 4 than for Li 2 ZnSiO 4 .Although the forsterite crystal structure43 is completely different from the Li 2 MSiO 4 one, a similar explanation may tentatively be proposed for the Dq/B value of Cr IV :Mg 2 SiO 4 which is smaller than for Cr IV :Li 2 MSiO 4 .…”

Depth Profiling of Dark and Light Green Bacan: Construction of Material Characters Models from Elemental Analysis and Mineralogical Characterization

“…1.7.7) under Voigt peak shape profile (Howard asymmetry), and March-Dollase model [5][6][7][8]. The ICSD standards which have been used as reference structure models are ICSD #16596 (Tetraferriannite), ICSD #98790 (Calderonite), ICSD #68762 (Fayalite), ICSD #174 (Low-Quartz), ICSD #89669 (Dioptase), and ICSD #4337 (Liebenbergite) [9][10][11][12][13][14]. From the refinement process, it could be obtained accurate values of lattice parameter, atomic coordinates and their displacement values, and preferred orientation.…”

“…LG Bacan has Dioptase (CuSiO 3 ) which have contribution to releasing turquoise colour, small abundance of Liebenbergite (Ni 2 SiO 4 ) which have releasing green colour, and variant of Calderonite (Ca 2 CuP 2 O 9 ) [13,14]. DG Bacan has Fayalite (Fe 2 SiO 4 ) which has releasing green-to-dark brown colour and strong hardness level (6.5 mohs), and variant of Ferriannite (KCaFe 3 Si 3 O 12 ) has contribution to release brownish-black colour [9,11].…”