Natural kalsilite, KAlSiO<sub>2</sub>, and P31c symmetry; crystal structure and twinning

Cellai, Daniela; Bonazzi, Paola; Carpenter, Myra A.

doi:10.2138/am-1997-3-405

Cited by 23 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The structure was refined to an R index of 3.8% and a GoF of 1.02 for a total of 196 refined parameters. Twinning by merohedry is well known for related compounds, e.g., kalsilite KAlSiO 4 (Cellai et al 1997) and RbLiCrO 4 (Makarova et al 1993); however, upon careful analysis of the structural data, we found no evidence of twinning in malinkoite. Final atom parameters are given in Table 3, selected interatomic distances are presented in Table 4, and a bond-valence analysis is shown in Table 5 There are five unique Na sites, each completely occupied by Na but with somewhat diverse coordinations.…”

Section: Solution and Refinement Of The Structure Of Malinkoitecontrasting

confidence: 61%

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

Sokolova¹,

Hawthorne²,

Khomyakov³

2001

The Canadian Mineralogist

View full text Add to dashboard Cite

The crystal structure of malinkoite, NaBSiO 4 , a 13.8964(4) Å, c 7.7001(2) Å, P6 3 , Z = 18, D x = 2.922 g cm -3 , from the Khibina-Lovozero complex, Kola peninsula, Russia, has been solved by direct methods and refined to an R index of 3.8% using 2094 unique observed (|F o | > 4F) reflections collected with a single-crystal diffractometer fitted with a CCD detector and MoK␣ X-radiation. Malinkoite is a framework borosilicate with a structure consisting of six-membered rings of regularly alternating (SiO 4 ) and (BO 4 ) tetrahedra, and Na located in the large channels extending along [001]. There are three unique Si sites, each occupied by Si and each coordinated by four O atoms in a tetrahedral arrangement, with distances of 1.625, 1.622 and 1.622 Å, respectively. There are three unique B sites, each occupied by B and each coordinated by four O atoms in a tetrahedral arrangement, with distances of 1.476, 1.476 and 1.473 Å, respectively. There are five unique Na sites, each completely occupied by Na. Three of the Na sites are [9]-coordinated, with distances of 2.626, 2.642 and 2.630 Å, respectively; the remaining two Na sites are [6]-coordinated, with distances of 2.444 and 2.440 Å, respectively. The (SiO 4 ) and (BO 4 ) tetrahedra link to form six-membered rings of two different configurations based on the following sequences of up (U) and down (D) linkages: UDUDUD and UUDUDD in the ratio of 1:2. Nine-coordinated Na polyhedra are located in big cages formed by stacking of UDUDUD rings. Stacking of UUDUDD rings produces smaller cages occupied by [6]-coordinated Na. In accord with the ratio of two types of rings, there are twelve Na octahedra and six [9]-coordinated Na polyhedra per unit cell in malinkoite. The framework topology is related to that of beryllonite NaBePO 4 .In the crystal structure of lisitsynite, KBSi 2 O 6 , four-membered rings consist of two (SiO 4 ) and two (BO 4 ) tetrahedra, and are linked into zig-zag chains (puckered ladders) along [001]. There are two types of chemically distinct six-and eight-membered rings: (4Si + 2B) and (5Si + B); (5Si + 3B) and (6Si + 2B). Two different pairs of six-membered and eight-membered rings, (4Si + 2B) and (5Si + 3B), and (5Si + B) and (6Si + 2B), respectively, form sheets on (100) and (010). Stacking of sheets and zig-zag chains gives rise to a three-dimensional framework. There are one-dimensional seven-ring channels along the c direction. Lisitsynite, KBSi 2 O 6 , and synthetic "boroleucite", K(Si 2 B)O 6 , may be regarded as polymorphs with different patterns of Si-B order. SOMMAIRE Nous avons résolu la structure cristalline de la malinkoïte, NaBSiO 4 , a 13.8964(4), c 7.7001 (2) Å, P6 3 , Z = 18, D x = 2.922 g cm -3 , provenant du complexe de Khibina-Lovozero, péninsule de Kola, en Russie, par méthodes directes, et l'avons affiné jusqu'à un résidu R de 3.8% en utilisant 2094 réflexions uniques observées (|F o | > 4F), prélevées avec un diffractomètre pour cristaux uniques muni d'un détecteur CCD et avec rayonnement MoK␣. Il s'...

show abstract

Section: Solution and Refinement Of The Structure Of Malinkoitecontrasting

confidence: 61%

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

Sokolova¹,

Hawthorne²,

Khomyakov³

2001

The Canadian Mineralogist

View full text Add to dashboard Cite

show abstract

“…The experiments in this study have been performed using a metamorphic kalsilite from the sample studied by Carpenter and Cellai (1996) and Cellai et al (1997Cellai et al ( , 1999. The kalsilite crystals were collected from a granulite facies gneiss from Punalur, Kerala district, southern India, and provided by M. Santosh.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Crystals of kalsilite that were annealed at 900 °C for 1 h by Cellai and Carpenter (1999), and had previously exhibited P6 3 symmetry at room temperature, were selected. Surprisingly, all of the crystals checked by singlecrystal X-ray diffraction showed P31c symmetry: the P31c-to-P6 3 phase transition upon heating reported as irreversible by Cellai et al (1997) is actually reversible, on the timescale of a decade. Gatta et al (2010a) described the thermo-elastic behavior at low T and suggested that the negative thermal expansion along [0001] observed between 100 and 300 K is a consequence of a decrease in the tetrahedral tilts with increasing temperature.…”

Section: Introductionmentioning

confidence: 97%

“…In particular, Cellai et al (1997) reported the crystal structure of an essentially Na-free metamorphic kalsilite (i.e., K/Na molar ratio ~350) from Punalur (Kerala district in southern India). The authors showed that the structure has P31c symmetry at room conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The high-temperature structure shows strong similarities with that of the volcanic Na-bearing kalsilite at room conditions (i.e., with P6 3 symmetry at room conditions, Perrotta and Smith 1965). Recently, Gatta et al (2010a) investigated the low-T behavior of the P31c kalsilite, using crystals of metamorphic kalsilite from the sample studied by Carpenter and Cellai (1996) and Cellai et al (1997Cellai et al ( , 1999. Crystals of kalsilite that were annealed at 900 °C for 1 h by Cellai and Carpenter (1999), and had previously exhibited P6 3 symmetry at room temperature, were selected.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phase stability, elastic behavior, and pressure-induced structural evolution of kalsilite: A ceramic material and high-T/high-P mineral

Gatta

Angel

Zhao

et al. 2011

American Mineralogist

View full text Add to dashboard Cite

The phase stability, elastic behavior, and pressure-induced structural evolution of a natural metamorphic kalsilite (ideal formula KAlSiO 4 ) from Punalur (Kerala district in southern India), with P31c symmetry and a K/Na molar ratio of ~350, has been investigated by in situ X-ray single-crystal diffraction up to ~7 GPa with a diamond-anvil cell under hydrostatic conditions. At high-pressure, a previously unreported iso-symmetric first-order phase transition occurs at ~3.5 GPa. The volume compression of the two phases is described by third-order Birch-Murnaghan equations-of-state: V 0 = 201.02(1) Å 3 , K T0 = 59.7(5) GPa, K′ = 3.5(3) for the low-P polymorph, and V 0 = 200.1(13) Å 3 , K T0 = 44(8) GPa, K′ = 6.4(20) for the high-P polymorph. The pressure-induced structural evolution in kalsilite up to 7 GPa appears to be completely reversible. The compression of both phases involves tetrahedral rotations around [0001], which close up the channels within the framework. In addition, compression of the low-pressure phase involves tilting of the tetrahedra. The major structural change at the phase transition is an increase in the tilting of the tetrahedra, but with a reversion of the tetrahedral rotations to the value found at ambient conditions. This behavior is in distinct contrast to that of nepheline, which has a tetrahedral framework of the same topology.

show abstract

8.1.6.1 Kalsilite, nepheline, carnegieite, and related silicates

Burzo

2011

Tectosilicates

View full text Add to dashboard Cite

Natural kalsilite, KAlSiO₂, and P31c symmetry; crystal structure and twinning

Cited by 23 publications

References 0 publications

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

Phase stability, elastic behavior, and pressure-induced structural evolution of kalsilite: A ceramic material and high-T/high-P mineral

8.1.6.1 Kalsilite, nepheline, carnegieite, and related silicates

Contact Info

Product

Resources

About

Natural kalsilite, KAlSiO2, and P31c symmetry; crystal structure and twinning

Cited by 23 publications

References 0 publications

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

THE CRYSTAL CHEMISTRY OF MALINKOITE, NaBSiO4, AND LISITSYNITE, KBSi2O6, FROM THE KHIBINA LOVOZERO COMPLEX, KOLA PENINSULA, RUSSIA

Phase stability, elastic behavior, and pressure-induced structural evolution of kalsilite: A ceramic material and high-T/high-P mineral

8.1.6.1 Kalsilite, nepheline, carnegieite, and related silicates

Contact Info

Product

Resources

About

Natural kalsilite, KAlSiO₂, and P31c symmetry; crystal structure and twinning