Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

AbstractTwo quintinite polytypes, 3R and 2T, which are new for the Kovdor alkaline-ultrabasic complex, have been structurally characterized. The crystal structure of quintinite-2T was solved by direct methods and refined to R1 = 0.048 on the basis of 330 unique reflections. The structure is trigonal, P$\bar 3$c1, a = 5.2720(6), c = 15.113(3) Å and V = 363.76(8) Å3. The crystal structure consists of [Mg2Al(OH)6]+ brucite-type layers with an ordered distribution of Mg2+ and Al3+ cations according to the $\sqrt 3 $ × $\sqrt 3 $ superstructure with the layers stacked according to a hexagonal type. The complete layer stacking sequence can be described as …=Ab1C = Cb1A=…. The crystal structure of quintinite-3R was solved by direct methods and refined to R1 = 0.022 on the basis of 140 unique reflections. It is trigonal, R$\bar 3$m, a = 3.063(1), c = 22.674(9) Å and V = 184.2(1) Å3. The crystal structure is based upon double hydroxide layers [M2+,3+(OH)2] with disordered distribution of Mg, Al and Fe and with the layers stacked according to a rhombohedral type. The stacking sequence of layers can be expressed as …=АB = BC = CA=… The study of morphologically different quintinite generations grown on one another detected the following natural sequence of polytype formation: 2H → 2T → 1M that can be attributed to a decrease of temperature during crystallization. According to the information-based approach to structural complexity, this sequence corresponds to the increasing structural information per atom (IG): 1.522 → 1.706 → 2.440 bits, respectively. As the IG value contributes negatively to the configurational entropy of crystalline solids, the evolution of polytypic modifications during crystallization corresponds to the decreasing configurational entropy. This is in agreement with the general principle that decreasing temperature corresponds to the appearance of more complex structures.

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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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Crystal chemistry of natural layered double hydroxides. 2. Quintinite-1M: first evidence of a monoclinic polytype in M2+-M3+ layered double hydroxides

Mineralogical Magazine ◽

10.1180/minmag.2010.074.5.833 ◽

2010 ◽

Vol 74 (5) ◽

pp. 833-840 ◽

Cited By ~ 22

Author(s):

S. V. Krivovichev ◽

V. N. Yakovenchuk ◽

E. S. Zhitova ◽

A. A. Zolotarev ◽

Y. A. Pakhomovsky ◽

...

Keyword(s):

Layered Double Hydroxides ◽

Direct Methods ◽

Monoclinic Space Group ◽

Stacking Sequence ◽

Trivalent Metal ◽

Diffuse Intensity ◽

Layer Stacking ◽

Complete Layer ◽

Double Hydroxides ◽

Alkaline Massif

AbstractQuintinite-1M, [Mg4Al2(OH)12](CO3)(H2O)3, is the first monoclinic representative of both synthetic and natural layered double hydroxides (LDHs) based on octahedrally coordinated di- and trivalent metal cations. It occurs in hydrothermal veins in the Kovdor alkaline massif, Kola peninsula, Russia. The structure was solved by direct methods and refined to R1 = 0.031 on the basis of 304 unique reflections. It is monoclinic, space group C2/m, a = 5.266(2), b = 9.114(2), c = 7.766(3) Å, β = 103.17(3)°, V = 362.9(2) Å3. The diffraction pattern of quintinite-1M contains sharp reflections corresponding to the layer stacking sequence characteristic of the 3R rhombohedral polytype, and rows of weak superlattice reflections superimposed upon a background of streaks of modulated diffuse intensity parallel to c*. These superlattice reflections indicate the formation of a 2-D superstructure due to Mg-Al ordering. The structure consists of ordered metal hydroxide layers and a disordered interlayer. As the unit cell contains exactly one layer, the polytype nomenclature dictates that the mineral be called quintinite-1M. The complete layer stacking sequence can be described as …=Ac1B=Ba1C=Cb1A=… Quintinite-1M is isostructural with the monoclinic polytype of [Li2Al4(OH)12](CO3)(H2O)3.

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Zincalstibite-9R: the first nine-layer polytype with the layered double hydroxide structure-type

Mineralogical Magazine ◽

10.1180/minmag.2012.076.5.01 ◽

2012 ◽

Vol 76 (5) ◽

pp. 1337-1345 ◽

Cited By ~ 13

Author(s):

S. J. Mills ◽

A. G. Christy ◽

A. R. Kampf ◽

R. M. Housley ◽

G. Favreau ◽

...

Keyword(s):

Crystal Structure ◽

Layered Double Hydroxide ◽

Structure Type ◽

Refractive Indices ◽

Stacking Sequence ◽

Oh Groups ◽

Layer Stacking ◽

Periodic Layer ◽

Double Hydroxide ◽

The Ideal

AbstractZincalstibite-9R, a new polytype in the hydrotalcite supergroup is reported from the Monte Avanza mine, Italy. It occurs as pale blue curved disc-like tablets flattened on {001} intergrown to form rosettes typically less than 50 μm in diameter, with cyanophyllite and linarite in cavities in baryte. Zincalstibite-9R is uniaxial (–), with refractive indices ω = 1.647(2) and ε = 1.626(2) measured in white light. The empirical formula (based on 12 OH groups) is (Zn1.092+Cu0.872+Al0.04)Σ2.00Al1.01(Sb0.975+Si0.02)Σ0.99(OH)12, and the ideal formula is (Zn,Cu)2Al(OH)6[Sb(OH)6]. Zincalstibite-9R crystallizes in space group R, with a = 5.340(2), c = 88.01(2) Å, V = 2173.70(15) Å3 and Z = 9. The crystal structure was refined to R1 = 0.0931 for 370 unique reflections [Fo > 4σ(F)] and R1 = 0.0944 for all 381 unique reflections. It has the longest periodic layer stacking sequence for a layered double hydroxide compound reported to date.

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Crystal chemistry of natural layered double hydroxides. 3. The crystal structure of Mg,Al-disordered quintinite-2H

Mineralogical Magazine ◽

10.1180/minmag.2010.074.5.841 ◽

2010 ◽

Vol 74 (5) ◽

pp. 841-848 ◽

Cited By ~ 22

Author(s):

E. S. Zhitova ◽

V. N. Yakovenchuk ◽

S. V. Krivovichev ◽

A. A. Zolotarev ◽

Y. A. Pakhomovsky ◽

...

Keyword(s):

Direct Methods ◽

Area Detector ◽

System A ◽

Layer Stacking ◽

Plate Area ◽

Higher Temperature ◽

Diffraction Patterns ◽

Double Hydroxide ◽

Double Hydroxides ◽

Alkaline Massif

AbstractTwo crystals of Mg, Al-disordered quintinite-2H (Q1 and Q2), [Mg4Al2(OH)12](CO3)(H2O)3, from the Kovdor alkaline massif, Kola peninsula, Russia, have been characterized chemically and structurally. Both crystals have hexagonal symmetry, P63/mcm, a = 3.0455(10)/3.0446(9), c = 15.125(7)/15.178(5) Å, V = 121.49(8)/121.84(6) Å3. The structures of the two crystals have been solved by direct methods and refined to R1 = 0.046 and 0.035 on the basis of 76 and 82 unique observed reflections for Q1 and Q2, respectively. Diffraction patterns obtained using an image-plate area detector showed the almost complete absence of superstructure reflections which would be indicative of the Mg-Al ordering in metal hydroxide layers, as has been observed recently for other quintinite polytypes. The crystal structures are based on double hydroxide layers [M(OH)2] with an average disordered distribution of Mg2+ and Al3+ cations. Average <M–OH> bond lengths for the metal site are 2.017 and 2.020 Åfor Q1 and Q2, respectively, and are consistent with a highly Mg-Al disordered, average occupancy. The layer stacking sequence can be expressed as …=AC=CA=…, corresponding to a Mg-Al-disordered 2H polytype of quintinite. The observed disorder is probably the result of a relatively high temperature of formation for the Q1 and Q2 crystals compared to ordered polytypes. This suggestion is in general agreement with the previous observations which demonstrated, for the Mg-Al system, a higher-temperature regime of formation of the hexagonal (or pseudo-hexagonal in the case of quintinite-2H-3c) 2H polytype in comparison to the rhombohedral (or pseudo-rhombohedral in the case of quintinite-1M) 3R polytype.

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Farneseite, a new mineral of the cancrinite - sodalite group with a 14-layer stacking sequence: occurrence and crystal structure

European Journal of Mineralogy ◽

10.1127/0935-1221/2005/0017-0839 ◽

2006 ◽

Vol 17 (6) ◽

pp. 839-846 ◽

Cited By ~ 17

Author(s):

Fernando Cá mara ◽

Fabio Bellatreccia ◽

Giancarlo Della Ventura ◽

Annibale Mottana

Keyword(s):

Crystal Structure ◽

New Mineral ◽

Stacking Sequence ◽

Layer Stacking

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The Principle of Maximal Simplicity for Modular Inorganic Crystal Structures

Crystals ◽

10.3390/cryst11121472 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1472

Author(s):

Sergey V. Krivovichev

Keyword(s):

Crystal Structures ◽

Structure Prediction ◽

Structural Information ◽

Structural Complexity ◽

Configurational Entropy ◽

Sensu Stricto ◽

Least Action ◽

Inorganic Crystal ◽

Principle Of Least Action ◽

Structure Description

Modularity is an important construction principle of many inorganic crystal structures that has been used for the analysis of structural relations, classification, structure description and structure prediction. The principle of maximal simplicity for modular inorganic crystal structures can be formulated as follows: in a modular series of inorganic crystal structures, the most common and abundant in nature and experiments are those arrangements that possess maximal simplicity and minimal structural information. The latter can be quantitatively estimated using information-based structural complexity parameters. The principle is applied for the modular series based upon 0D (lovozerite family), 1D (biopyriboles) and 2D (spinelloids and kurchatovite family) modules. This principle is empirical and is valid for those cases only, where there are no factors that may lead to the destabilization of simplest structural arrangements. The physical basis of the principle is in the relations between structural complexity and configurational entropy sensu stricto (which should be distinguished from the entropy of mixing). It can also be seen as an analogy of the principle of least action in physics.

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Structural complexity and configurational entropy of crystals

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s205252061501906x ◽

2016 ◽

Vol 72 (2) ◽

pp. 274-276 ◽

Cited By ~ 24

Author(s):

Sergey V. Krivovichev

Keyword(s):

Crystal Structure ◽

Statistical Approach ◽

Structural Complexity ◽

Configurational Entropy ◽

Physical Nature ◽

Shannon Information ◽

Crystalline Solid ◽

Complex Structures ◽

Negative Contribution ◽

Acta Cryst

Using a statistical approach, it is demonstrated that the complexity of a crystal structure measured as the Shannon information per atom [Krivovichev (2012).Acta Cryst.A68, 393–398] represents a negative contribution to the configurational entropy of a crystalline solid. This conclusion is in full accordance with the general agreement that information and entropy are reciprocal variables. It also agrees well with the understanding that complex structures possess lower entropies relative to their simpler counterparts. The obtained equation is consistent with the Landauer principle and points out that the information encoded in a crystal structure has a physical nature.

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Crystal structure of a new representative of the cancrinite group with a 12-layer stacking sequence of tetrahedral rings

Crystallography Reports ◽

10.1134/1.1780629 ◽

2004 ◽

Vol 49 (4) ◽

pp. 635-642 ◽

Cited By ~ 9

Author(s):

K. A. Rozenberg ◽

A. N. Sapozhnikov ◽

R. K. Rastsvetaeva ◽

N. B. Bolotina ◽

A. A. Kashaev

Keyword(s):

Crystal Structure ◽

Stacking Sequence ◽

Layer Stacking

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Polytypism, polymorphism, and superconductivity in TaSe2−xTex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1502460112 ◽

2015 ◽

Vol 112 (11) ◽

pp. E1174-E1180 ◽

Cited By ~ 50

Author(s):

Huixia Luo ◽

Weiwei Xie ◽

Jing Tao ◽

Hiroyuki Inoue ◽

András Gyenis ◽

...

Keyword(s):

Crystal Structure ◽

Physical Properties ◽

Single Layer ◽

Large Family ◽

Layered Materials ◽

Stacking Sequence ◽

Superconducting Transition ◽

Surprising Effect ◽

Layer Stacking ◽

Structural Layer

Polymorphism in materials often leads to significantly different physical properties—the rutile and anatase polymorphs of TiO2 are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer-stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivity of TaSe2, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access two stable polytypes and two stable polymorphs in the TaSe2−xTex solid solution and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. The reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present or from a surprising effect of the layer-stacking sequence on electronic properties that are typically expected to be dominated by the properties of a single layer in materials of this kind.

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