Altisite Na3K6Ti2[Al2Si8O26]Cl3 a new hyperalkaline aluminosilicate from Kola Peninsula (Russia) related to lemoynite: crystal structure and thermal evolution

The thermal evolution of the crystal structure and phase transitions of KNbO 3 were investigated by high-temperature powder X-ray diffraction and Rietveld refinement of the diffraction data. Two phase transitions from orthorhombic ( Amm 2) to tetragonal ( P 4 mm ) and from tetragonal to cubic ( P m 3 ¯ m ) were confirmed, both on heating and cooling. Both phase transitions are first order based on the observed hysteresis. The mixed displacive and order–disorder nature of the tetragonal to cubic transition is argued based on symmetry and apparent divergence of the atomic positions from pseudo-cubic values. The transition between the orthorhombic and tetragonal phase shows no temperature-dependence for atomic positions and only thermal expansion of the unit cell parameters and is thus discussed in relation to a lattice dynamical instability.

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Thermal Evolution of the Crystal Structure of the Rhombohedral Bi0.75Sr0.25O1.375 Phase: A Single Crystal Neutron Diffraction Study

Journal of Solid State Chemistry ◽

10.1006/jssc.1994.1255 ◽

1994 ◽

Vol 112 (1) ◽

pp. 1-8 ◽

Cited By ~ 46

Author(s):

D. Mercurio ◽

J.C. Champarnaud-Mesjard ◽

B. Frit ◽

P. Conflant ◽

J.C. Boivin ◽

...

Keyword(s):

Crystal Structure ◽

Neutron Diffraction ◽

Single Crystal ◽

Diffraction Study ◽

Thermal Evolution ◽

Neutron Diffraction Study

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From structure topology to chemical composition. XXIII. Revision of the crystal structure and chemical formula of zvyaginite, Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a seidozerite-supergroup mineral from the Lovozero alkaline massif, Kola peninsula, Russia

Mineralogical Magazine ◽

10.1180/minmag.2017.081.015 ◽

2017 ◽

Vol 81 (6) ◽

pp. 1533-1550 ◽

Cited By ~ 4

Author(s):

E. Sokolova ◽

A. Genovese ◽

A. Falqui ◽

F.C. Hawthorne ◽

F. Cámara

Keyword(s):

Crystal Structure ◽

Kola Peninsula ◽

Microprobe Analysis ◽

Structural Formula ◽

Chemical Formula ◽

Titanium Silicate ◽

Structure Topology ◽

Diffraction Patterns ◽

Alkaline Massif ◽

The Ideal

AbstractThe crystal structure and chemical formula of zvyaginite, ideally Na2ZnTiNb2(Si2O7)2O2(OH)2(H2O)4, a lamprophyllite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia have been revised. The crystal structurewas refined with a new origin in space group C1, a = 10.769(2), b = 14.276(3), c = 12.101(2) Å, α = 105.45(3), β = 95.17(3), γ = 90.04(3)°, V = 1785.3(3.2) Å3, R1 = 9.23%. The electron-microprobe analysis gave the following empirical formula [calculated on 22 (O + F)]: (Na0.75Ca0.09K0.04□1.12)Σ2 (Na1.12Zn0.88Mn0.17Fe2+0.04□0.79)Σ3 (Nb1.68Ti1.25Al0.07)Σ3 (Si4.03O14)O2 [(OH)1.11F0.89]Σ2(H2O)4, Z = 4. Electron-diffraction patterns have prominent streaking along c* and HRTEM images show an intergrowth of crystalline zvyaginite with two distinct phases, both of which are partially amorphous. The crystal structure of zvyaginite is an array of TS (Titanium-Silicate) blocks connected via hydrogen bonds between H2O groups. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the [6]MO(1,4,5) sites are occupied mainly by Ti, Zn and Na and the [6]MO(2,3) sites are occupied by Na at less than 50%. In the H sheet, the [6]MH(1,2) sites are occupied mainly by Nb and the [8]AP(1) and [8]AP(2) sites are occupied mainly by Na and □. The MH and AP polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula is Na□Nb2NaZn□Ti(Si2O7)2O2(OH)2(H2O)4. Zvyaginite is a Zn-bearing and Na-poor analogue of epistolite, ideally (Na□)Nb2Na3Ti(Si2O7)2O2(OH)2(H2O)4. Epistolite and zvyaginite are related by the following substitution in the O sheet of the TS-block: (Naþ 2 )epi↔Zn2+ zvy +□zvy. The doubling of the t1 and t2 translations of zvyaginite relative to those of epistolite is due to the order of Zn and Na along a (t1) and b (t2) in the O sheet of zvyaginite.

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CARBOBYSTRITE, Na8[Al6Si6O24](CO3){middle dot}4H2O, A NEW CANCRINITE-GROUP MINERAL SPECIES FROM THE KHIBINA ALKALINE MASSIF, KOLA PENINSULA, RUSSIA: DESCRIPTION AND CRYSTAL STRUCTURE

The Canadian Mineralogist ◽

10.3749/canmin.48.2.291 ◽

2010 ◽

Vol 48 (2) ◽

pp. 291-300 ◽

Cited By ~ 8

Author(s):

A. P. Khomyakov ◽

F. Camara ◽

E. Sokolova

Keyword(s):

Crystal Structure ◽

Kola Peninsula ◽

Mineral Species ◽

Group Mineral ◽

Alkaline Massif

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Thermal Evolution of Magnetic Properties and Crystal Structure in Compositionally Modulated Al/Ni Thin Films

MRS Proceedings ◽

10.1557/proc-232-171 ◽

1991 ◽

Vol 232 ◽

Cited By ~ 1

Author(s):

A. Waknis ◽

E. Haftek ◽

M. Tan ◽

J. A. Barnard ◽

E. Tsang

Keyword(s):

Crystal Structure ◽

Thin Films ◽

Magnetic Properties ◽

Thermal Evolution ◽

Dead Layer ◽

Multilayer Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

The Individual ◽

Deposited Films

ABSTRACTPeriodic multilayer thin films of the form (xAl/yNi)n were grown by alternate deposition of pure Al and Ni using dc-magnetron sputtering. The thicknesses of the individual Al and Ni layers are given by x and y, respectively, and the total number of bilayer units is n. For this set of experiments, x was fixed at 3.5 nm while y was systematically varied from 2.4 to 154 nm. The films were tested in as-deposited and annealed states for magnetic properties using a vibrating sample magnetometer and for crystal structure by x-ray diffraction. In both the as-deposited and annealed samples the magnetization per unit volume of Ni declined as the Ni layer thickness decreased. This result can be interpreted in terms of a magnetically ‘dead’ layer at the Al/Ni interfaces. The width of the dead layer increased from 2.9 nm to 5.8 nm on annealing. Magnetic properties were correlated with crystal structure experiments by x-ray diffraction. As-deposited films yielded a Ni(111) texture. The Ni (111) peak decreased in intensity and broadened as the Ni thickness declined. Annealing produced evidence for the growth of the intermetallic NiAl3.

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SAAMITE, Ba TiNbNa3Ti(Si2O7)2O2(OH)2(H2O)2, A GROUP-III Ti-DISILICATE MINERAL FROM THE KHIBINY ALKALINE MASSIF, KOLA PENINSULA, RUSSIA: DESCRIPTION AND CRYSTAL STRUCTURE

The Canadian Mineralogist ◽

10.3749/canmin.1400043 ◽

2014 ◽

Vol 52 (4) ◽

pp. 745-762 ◽

Cited By ~ 6

Author(s):

F. Camara ◽

E. Sokolova ◽

Y. A. Abdu ◽

F. C. Hawthorne

Keyword(s):

Crystal Structure ◽

Kola Peninsula ◽

Group Iii ◽

Alkaline Massif ◽

Khibiny Alkaline Massif

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Crystal chemistry of natural layered double hydroxides. I. Quintinite-2H-3c from the Kovdor alkaline massif, Kola peninsula, Russia

Mineralogical Magazine ◽

10.1180/minmag.2010.074.5.821 ◽

2010 ◽

Vol 74 (5) ◽

pp. 821-832 ◽

Cited By ~ 28

Author(s):

S. V. Krivovichev ◽

V. N. Yakovenchuk ◽

E. S. Zhitova ◽

A. A. Zolotarev ◽

Y. A. Pakhomovsky ◽

...

Keyword(s):

Crystal Structure ◽

Kola Peninsula ◽

Direct Methods ◽

Stacking Sequence ◽

Layer Sequence ◽

Layer Stacking ◽

Double Hydroxide ◽

Double Hydroxides ◽

First Time ◽

Alkaline Massif

AbstractThe crystal structure of quintinite-2H-3c, [Mg4Al2(OH)12](CO3)(H2O)3, from the Kovdor alkaline massif, Kola peninsula, Russia, was solved by direct methods and refined to an agreement index (R1) of 0.055 for 484 unique reflections with |Fo| ≥ 4σF. The mineral is rhombohedral, R32, a = 5.2745(7), c = 45.36(1) Å. The diffraction pattern of the crystal has strong and sharp Bragg reflections having h–k = 3n and l = 3n and lines of weak superstructure reflections extended parallel to c* and centred at h–k ≠ 3n. The structure contains six layers within the unit cell with the layer stacking sequence of …AC=CA=AC=CA=AC=CA… The Mg and Al atoms are ordered in metal hydroxide layers to form a honeycomb superstructure. The full superstructure is formed by the combination of two-layer stacking sequence and Mg-Al ordering. This is the first time that a long-range superstructure in carbonate-bearing layered double hydroxide (LDH) has been observed. Taking into account Mg-Al ordering, the unique layer sequence can be written as …=Ab1C=Cb1A=Ab2C=Cb2A=Ab3C=Cb3A=… The use of an additional suffix is proposed in order to distinguish between LDH polytypes having the same general stacking sequence but with different c parameters compared with the ‘standard’ polytype. According to this notation, the quintinite studied here can be described as quintinite-2H-3c or quintinite-2H-3c[6R], indicating the real symmetry.

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