The nepheline-kalsilite system; Part I, X-ray data for the crystalline phases

Smith, J. V.; Tuttle, O. F.

doi:10.2475/ajs.255.4.282

Cited by 83 publications

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“…[112,152,153], 1523 K [133], and 1527 K [151]), carnegieite (a-carnegieite) is the stable NaAlSiO 4 compound, and has a derivative structure of the SiO 2 high-cristobalite structure [123]. According to Barth et al [112], a-carnegieite is cubic with the space group P2 1 3 and contains 4 NaAlSiO 4 per unit cell.…”

Section: Enthalpy Of Transformationmentioning

confidence: 99%

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Thermodynamic modeling of the (Al2O3+Na2O), (Al2O3+Na2O+SiO2), and (Al2O3+Na2O+AlF3+NaF) systems

Lambotte

Chartrand

2013

The Journal of Chemical Thermodynamics

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Section: Enthalpy Of Transformationmentioning

confidence: 99%

“…Nepheline transforms at around 1148 K [114] (1083 K [132], 1173 K [133], 1123 K [134]) to a high-temperature orthorhombic [133] nepheline form. Most of the reported data are for nepheline samples containing minor impurities (K and Ca being readily soluble in nepheline [135]).…”

Section: The (Al 2 O 3 + Na 2 O + Sio 2 ) Ternary Systemmentioning

confidence: 99%

Thermodynamic modeling of the (Al2O3+Na2O), (Al2O3+Na2O+SiO2), and (Al2O3+Na2O+AlF3+NaF) systems

Lambotte

Chartrand

2013

The Journal of Chemical Thermodynamics

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“…The Si-A1 ordering of this product has stopped somewhere in between pure Si(1AI) and pure Si(4A1). High-carnegieite (Smith and Turtle, 1957) undergoes a phase transition at 690~ (Klingenberg et aL, 1981) to a much lower symmetry low-temperature polymorph as represented by Figure 3d, though the lower symmetry results from distortion of the ideal cubic framework rather than any rearrangement of Si and A1. While the Step 4 produced material cannot be readily indexed to a unique unit cell, the general similarity between the XRD, NMR and FTIR data for the synthetic carnegieite and the Step 4 product leads us to conclude that the Step 4 product is structurally closely related to lowcarnegieite.…”

Section: Step 2 Heating the Intercalatementioning

confidence: 99%

Structural Characterisation of Kaolinite:NaCl Intercalate and its Derivatives

Thompson

Uwins

Whittaker

1992

Clays and clay miner.

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Abstraet--Kaolinite:NaC1 intercalates with basal layer dimensions of 0.95 and 1.25 nm have been prepared by direct reaction of saturated aqueous NaC1 solution with well-crystallized source clay KGa-1. The intercalates and their thermal decomposition products have been studied by XRD, solid-state 23Na, 27A1, and 29Si MAS NMR, and FTIR. Intercalate yield is enhanced by dry grinding of kaolinite with NaC1 prior to intercalation. The layered structure survives dehydroxylation of the kaolinite at 500"--600"C and persists to above 800~ with a resultant tetrahedral aluminosilicate framework. Excess NaC1 can be readily removed by rinsing with water, producing an XRD 'amorphous' material. Upon heating at 900"C this material converts to a well-crystallized framework aluminosilicate closely related to low-camegieite, NaA1SiO4, some 350~ below its stability field. Reaction mechanisms are discussed and structural models proposed for each of these novel materials.

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“…The most extensive data refer to the system NaA1SiO4-KA1SiO~ (Sahama etal. 1956;Smith and Tuttle 1957;Donnay et al 1959;Hamilton and MacKenzie 1960;Roux 1974;Ferry and Blencoe 1978) and show that the kalsilite cell is found for compositions from 68 to ca 100 mol% KA1SiO4, and nepheline from ca 0 to 69 mol% KA1SiO4, the wide ranges of solid solution becoming smaller for crystals grown at lower temperatures. For ca 70 mol% KAlSiO4, two further structures have recently been resolved, namely tetrakalsilite (Merlino et al 1985) and trikalsilite (Bonaccorsi et al 1988).…”

Section: Introductionmentioning

confidence: 99%

Ion exchange between tectosilicates with the nepheline-kalsilite framework and molten MNO3 or MO (M = Li, Na, K, Ag)

Sobrados

Gregorkiewitz

1993

Phys Chem Minerals

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Abstract. Natural nepheline, a synthetic Na-rich nepheline, and synthetic kalsilite were ion exchanged in molten MNO3 or MC1 (M=Li, Na, K, Ag) at 220-800 ~ C. Crystalline products were characterized by wet chemical and electron microprobe analysis, single crystal and powder X-ray diffraction, and transmission electron microscopy and diffraction. Two new compounds were obtained: Li-exchanged nepheline with a formula near (Li,Ko.3,D)Li~[A13(A1,Si)Si~O16] and a monoclinic unit cell with a=951.0(6) b=976.1(6) c=822.9(5) pm 7= 119.15 ~ and Ag-exchanged nepheline with a formula near (K,Na, D)Ag3[At3(A1,Si)Si40~6] and a hexagonal unit cell with a = 1007.4(8) c = 838.2(1.0) pm. Both compounds apparently retain the framework topology of the starting material. Ion exchange isotherms and structural data show that immiscibility between the end members is a general feature in the systems Na-Li, Na-Ag, and Na-K. For the system Na-K, a stepwise exchange is observed with (K,D)Na3[A13(AI,Si)Si40~6] as an intermediate composition which has the nepheline structure and is miscible with the sodian end member (Na,D)Na3[A13-(A1,Si)Si40~6], but not with the potassian end member (K,D)4[A13(A1,Si)Si4Oa6] which shows the kalsilite structure; there was no indication for the formation of trior tetrakalsilite (K/(K + Na) ~ 0.7) at the temperatures studied (350 and 800 ~ C). The exact amount of vacancies [] on the alkali site depends upon the starting material and was found to be conserved during exchange, with ca 0-0.2 and 0.3-0.4 vacancies per 16 oxygen atoms for the synthetic and natural precursors, respectively. Thermodynamic interpretation of the Na-K exchange isotherms shows, as one important result, that the sodian end member is unstable with respect to the intermediate at K/(K +Na)~ 0.25 by an amount of ca 45 kJ/mol Na in the large cavity at 800 ~ C (52 kJ/mol at 350 ~ C).

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The nepheline-kalsilite system; Part I, X-ray data for the crystalline phases

Cited by 83 publications

References 0 publications

Thermodynamic modeling of the (Al2O3+Na2O), (Al2O3+Na2O+SiO2), and (Al2O3+Na2O+AlF3+NaF) systems

Thermodynamic modeling of the (Al2O3+Na2O), (Al2O3+Na2O+SiO2), and (Al2O3+Na2O+AlF3+NaF) systems

Structural Characterisation of Kaolinite:NaCl Intercalate and its Derivatives

Ion exchange between tectosilicates with the nepheline-kalsilite framework and molten MNO3 or MO (M = Li, Na, K, Ag)

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