Phase stability and pressure-induced structural transitions at zero temperature in ZnSiO3and Zn2SiO4

Karazhanov, Smagul; Ravindran, P.; Vajeeston, Ponniah; Ulyashin, A.; Fjellvåg, Helmer; Svensson, B. G.

doi:10.1088/0953-8984/21/48/485801

Cited by 23 publications

(25 citation statements)

References 40 publications

(83 reference statements)

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“…Therefore, it is tempting to speculate that phase III could have assumed an olivine-like structure under the pressure and temperature condition for its synthesis, and Zn cations could have migrated from octahedral sites to adjacent tetrahedral sites during recovery to ambient condition as a result of its strong preference for tetrahedral coordination. A previous first-principles calculation (Karazhanov et al 2009) and arguments based on packing density (Nalbandyan and Novikova 2012) have both suggested olivine as a possible high-pressure Zn 2 SiO 4 polymorph. It is likely that phase IV could also have existed with a different structure under high pressure and high temperature, and the Zn cations could have changed from octahedral to tetrahedral coordination accompanying structural changes during recovery to ambient condition.…”

Section: Stabilities Of Phases III and Iv Under High Pressure And Higmentioning

confidence: 94%

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

2013

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We report the crystal structures determined under ambient condition for two Zn 2 SiO 4 polymorphs synthesized at 6.5 GPa and 1,273 K (phase III) and 8 GPa and 1,273 K (phase IV) and also compare their 29 Si MAS NMR spectroscopic characteristics with those of other Zn 2 SiO 4 polymorphs (phases I, II and V). Electron microprobe analysis revealed that both of phases III and IV are stoichiometric like the lower-pressure polymorphs (phases I and II), contrary to previous report. The crystal structures were solved using an ab initio structure determination technique from synchrotron powder X-ray diffraction data utilizing local structural information from 29 Si MAS NMR as constraints and were further refined with the Rietveld technique. Phase III is orthorhombic (Pnma) with a = 10.2897(5), b = 6.6711(3), c = 5.0691(2) Å . It is isostructural with the high-temperature (Zn 1.1 Li 0.6 Si 0.3 )-SiO 4 phase and may be regarded as a 'tetrahedral olivine' type that resembles the 'octahedral olivine' structure in the (approximately hexagonally close packed) oxygen arrangement and tetrahedral Si positions, but has Zn in tetrahedral, rather than octahedral coordination. Phase IV is orthorhombic (Pbca) with a = 10.9179(4), b = 9.6728(4), c = 6.1184(2) Å . It also consists of tetrahedrally coordinated Zn and Si and features unique edge-shared Zn 2 O 6 dimers. The volumes per formula under ambient condition for phases III and IV are both somewhat larger than that of the lower-pressure polymorph, phase II, suggesting that the two phases may have undergone structural changes during temperature quench and/or pressure release.

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Section: Stabilities Of Phases III and Iv Under High Pressure And Higmentioning

confidence: 94%

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

2013

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“…Atomic charges are estimated with the partition scheme proposed by Bader, 24,25 and atomic configurations are plotted with VESTA. 26 Bulk calculations While several zinc silicate polymorphs have been reported to form in thin films and at Si/ZnO or SiO x /ZnO interfaces [14][15][16] , we have focused on the tetragonal t-Zn 2 SiO 4 phase, which forms at a pressure of about 25 kbar, 27 and is only slightly less stable than the rhombohedral willemite. It is the second most stable phase of a series of five zinc silicate polymorphs formed when applying pressure to the willemite mineral, and has been already stabilized in the presence of interfacial strain.…”

Section: Computational Methods and Settingsmentioning

confidence: 99%

“…It is the second most stable phase of a series of five zinc silicate polymorphs formed when applying pressure to the willemite mineral, and has been already stabilized in the presence of interfacial strain. 14,16 The atomic structure of the t-Zn 2 SiO 4 polymorph (also referred to as Zn 2 SiO 4 -II) 16,27,28 is represented in Figure 1 until the stress tensor and all forces become smaller than 0.01 eV Å −3 and 0.01 eV Å −1 , respectively. We find that with a Γ-centered 6×6×4 Monkhorst-Pack grid the calculated structural characteristics (lattice parameters, bond lengths, and angles) are converged to within 0.01 Å and 0.1 • .…”

Section: Computational Methods and Settingsmentioning

confidence: 99%

“…11 Aside application of inox buffer layers, as proposed for the similar zinc/alumina interfaces, 12,13 an alternative solution may rely on the formation of a mixed interfacial oxide phase, such as zinc silicate Zn 2 SiO 4 . [14][15][16] Such interfacial phase would impact the interactions occurring at the interface and, depending on the thermodynamic conditions, could enhance the adhesion through various pathways. The lower density of silicon at the silicate surface could, e.g., prevent the formation of siloxane rings, while the existing network of Zn-O bonds could naturally propagate towards the zinc deposit, thus allowing a stronger adhesion.…”

Section: Introductionmentioning

confidence: 99%

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Surface thermodynamics of silicate compounds: the case of Zn₂SiO₄(001) surfaces and thin films

Baima

Goniakowski

Noguera

et al. 2019

Phys. Chem. Chem. Phys.

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Silicate compounds are ubiquitous in nature and display a vast variety of structures and properties. Thin silicate films may also form under specific conditions at interfaces between metals and silica. In the present study, we focus on zinc silicate and present a thorough density functional theory-based study of polar and non-polar (001) surfaces of various stoichiometry of its tetragonal polymorph t-Zn 2 SiO 4 . At the non-polar surfaces, the main features are the existence of the chain reconstruction at the ZnO termination, and the presence of unsaturated surface silanols at the SiO 2 termination. Stabilization of polar surfaces is provided by the formation of O 2− 2 peroxo groups, reduction of the surface or subsurface Si atoms or formation of Zn 2+ 2 groups, depending upon the surface stoichiometry. While the non-polar stoichiometric and ZnO rich terminations are the most stable in a large part of the accessible phase diagram, the SiO 2 termination is less stable due to the absence of siloxane group formation. We show that, while bulk Zn 2 SiO 4 is stable with respect to decomposition into the ZnO and SiO 2 oxides, the same is not true for ultra-thin films due to the fundamental difference of silicate and silica surface energies. Preliminary results show that a similar conclusion could be drawn Fe 2 SiO 4 . This study opens towards a deeper understanding and possible improvement of zinc adhesion at silica surfaces, of crucial industrial importance.

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“…The related compounds Zn 2 SnO 4 , Cd 2 SnO 4 , and In 2 CdO 4 have been examined 24 by VASP. Possibility of phase transitions between structural polymorphs of ZnSiO 3 and Zn 2 SiO 4 have been reported 25 by DFT calculations using the VASP package. However, to our knowledge, there is no systematic study on the electronic structure and optical properties of the different polymorphs of ZnSiO 3 and Zn 2 SiO 4 .…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and optical properties of ZnSiO3 and Zn2SiO4

Karazhanov

Ravindran

Fjellvåg

et al. 2009

Journal of Applied Physics

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The electronic structure and optical properties of orthorhombic, monoclinic, and rhombohedral (corundum type) modifications of ZnSiO 3 , and of rhombohedral, tetragonal, and cubic (spinel type) modifications of Zn 2 SiO 4 have been studied using ab initio density functional theory calculations. The calculated fundamental band gaps for the different polymorphs and compounds are in the range 2.22 -4.18 eV. The lowest conduction band is well dispersive similar to that found for transparent conducting oxides such as ZnO. This band is mainly contributed by Zn 4s electrons. The carrier effective masses were calculated and compared with those for ZnO.The topmost valence band is much less dispersive and contributed by O 2p and Zn 3d electrons.From the analysis of charge-density, charges residing in each sites, and electron localization function it is found that ionic bonding is mainly ruling in these compounds. The calculated optical dielectric tensors show that the optical properties of ZnSiO 3 and Zn 2 SiO 4 are almost isotropic in the visible part of the solar spectra and depend negligibly on the crystal structure. Within the 0-4 eV photon energy range the calculated magnitude of the absorption coefficient, reflectivity, refractive index, and extinction coefficient are smaller than 10 3 cm -1 , 0.15, 2.2, and 0.3, respectively for all 2 the ZnSiO 3 and Zn 2 SiO 4 phases considered in this work. This suggests that zinc silicates can be used as antireflection coatings. 71.15.-m; 71.22.+i PACS:

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Phase stability and pressure-induced structural transitions at zero temperature in ZnSiO₃and Zn₂SiO₄

Cited by 23 publications

References 40 publications

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

Surface thermodynamics of silicate compounds: the case of Zn₂SiO₄(001) surfaces and thin films

Electronic structure and optical properties of ZnSiO3 and Zn2SiO4

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Phase stability and pressure-induced structural transitions at zero temperature in ZnSiO3and Zn2SiO4

Cited by 23 publications

References 40 publications

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

Crystal structures of Zn2SiO4 III and IV synthesized at 6.5–8 GPa and 1,273 K

Surface thermodynamics of silicate compounds: the case of Zn2SiO4(001) surfaces and thin films

Electronic structure and optical properties of ZnSiO3 and Zn2SiO4

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Phase stability and pressure-induced structural transitions at zero temperature in ZnSiO₃and Zn₂SiO₄

Surface thermodynamics of silicate compounds: the case of Zn₂SiO₄(001) surfaces and thin films