Crystal structure of larnite β-Ca2SiO4 and specific features of polymorphic transitions in dicalcium orthosilicate

Yamnova, N. A.; Zubkova, N. V.; Eremin, N. N.; Zadov, Aleksandr E.; Газеев, В.М.

doi:10.1134/s1063774511020209

Cited by 64 publications

(28 citation statements)

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“…This feature didn't let us to use normal water based solutions for sample polishing and we had to move to ethanol based solutions. Such feature confirms that larnite conversion to the calsio-olivine didn't happen (calsio-olivine can dissolve in water at temperatures above 200°C) 19) and the lenticular phase observed in the sinter structures is still larnite.…”

Section: Discussionsupporting

confidence: 64%

“…Such an inversion is accompanied by a large volume change of almost 10% from 345.2 Å 3 (larnite) to 384.2 Å 3 (γ-Ca2SiO4). 19) Such a volume change could be enough to cause breakdown of the sinter and produce fine powder in a sinter structure with high volume fraction of larnite. However, the observation of a large fraction of larnite phase in the compact sinter doped with high TiO2 in the current study (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Sintering Characteristics of Titanium Containing Iron Ores

et al. 2014

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The effect of Ti-oxide on the sintering behaviour of iron ore has been studied by doping pure TiO2 to a sinter blend in laboratory tests. The results showed a considerable effect of TiO2 on sinter strength, where the tumble index increased with increasing TiO2% (up to 2.0%). However, doping more than 2.0% TiO2 to the sinter blend decreased its strength. The melting point of the sinter was also affected by increasing the TiO2 content, indicating a possible change in the coke consumption during industrial-scale sintering of Tibearing ores. Optical and electron microscopy studies of sinter structures confirmed a general improvement in the overall pore structure and sinter melt by increasing TiO2 content of the sinter blend up to 2.0%. An important feature of the sinter structure was the observation of perovskite phase formation and an increase in the volume fraction of this phase obtained by increasing TiO2. The formation of this perovskite phase was considered as an important reason for the reduction of the sinter melting point. Also, doping TiO2 to the sinter mix resulted in stabilizing and increasing the volume fraction of the larnite phase in the sinter structure.

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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Sintering Characteristics of Titanium Containing Iron Ores

et al. 2014

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“…Lime is present up to 1100°C. The unreacted clinker phases of cement-like b-dicalcium silicate are stable up to 600°C and are then transformed to the high-temperature variety (a-C 2 S in cement notation, a-dicalcium silicate) [40]. After thermal treatment at 1200°C, the periclase (ICDD-PDF 01-075-9568), cristobalite (ICDD-PDF 01-075-3164), dicalcium silicate (ICDD-PDF 00-031-0299) and melilite group Ca 2 (Mg,Fe,Al,Si) 3 O 7 (ICDD-PDF 04-016-3580) were observed.…”

Section: Resultsmentioning

confidence: 99%

“…In this case lower water absorption was obtained in comparison to the reference material (2.7 vs. 3.3 %). Also, the value of open porosity was the lowest [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] MPa, thus the standard requirements are fulfilled. It should be noted that the addition of 10 wt% of cement-asbestos did not reduce the compressive strength of ceramic material as compared to the sample with 5 wt% of this waste.…”

Section: Recycling Of the Transformation Product In Clinker Brick MIXmentioning

confidence: 99%

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

et al. 2015

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The aim of this study was to investigate the thermal behaviour of cement-asbestos wastes and to determine whether it is possible to use them in the production of building ceramics, e.g. clinker bricks. In the first part of the research, the process of cement-asbestos thermal decomposition was studied. This asbestos material contained the chrysotile and crocidolite variety of asbestos. The results of this study allowed to determine the lowest temperature of thermal treatment that provides asbestos detoxification. The second part of the paper presents the results of a preliminary study on using previously calcined cement-asbestos wastes as an additive to ceramic masses typical for clinker bricks. Green compacts containing various amounts of cement-asbestos wastes were sintered and then ceramic properties were determined. The results of the study indicate that calcined asbestos-containing materials can be used as one of the secondary raw materials in the production of clinker ceramics.

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“…7, supplementary materials 1 ). This deviation is characteristic of calcio-olivine (Smith et al 1965;Czaya 1971;Udagawa et al 1980;Mumme et al 1995;Gobechiya et al 2008, Yamnova et al 2011) and other Ca humite-group minerals (Kirfel et al 1983;Galuskina et al 2009Galuskina et al , 2012). Because the relatively rigid SiO 4 tetrahedra share three edges with the large CaO 6 octahedra, there are large angular distortions of the O-Ca-O angles.…”

Section: Crystal Structure Of Edgrewite and Hydroxyledgrewite And H-bmentioning

confidence: 90%

Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia

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et al. 2012

American Mineralogist

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Members of the edgrewite Ca 9 (SiO 4 ) 4 F 2 -hydroxyledgrewite Ca 9 (SiO 4 ) 4 (OH) 2 series, structural analogues of clinohumite-hydroxylclinohumite series, Mg 9 (SiO 4 ) 4 (F,OH) 2 , were discovered in xenoliths of carbonate-silicate rock altered to skarn within ignimbrites of the Upper Chegem volcanic structure, Kabardino-Balkaria, Northern Caucasus, Russia. The new minerals occur sparingly in zones containing bultfonteinite, hillebrandite, jennite, and chegemite, as well as rare relics of larnite and rondorfite enclosed in a matrix of hydroxylellestadite. Edgrewite and hydroxyledgrewite are largely altered to jennite in places with admixed zeophyllite and trabzonite, and are preserved as elongate relics mostly 0.1-0.4 mm long in the central part of atoll-like pseudomorphs. The new minerals form a solid-solution series Ca 9 (SiO 4 ) 4 (F,OH) 2 , in which the content of the edgrewite end-member Ca 9 (SiO 4 ) 4 F 2 ranges from 74% (F = 3.64 wt%) to 31% (F = 1.52 wt%).Structure refinement of crystals containing 51% and 37% of the edgrewite end-member gave, respectively, R 1 = 3.03%, space group P2 1 /b11 (no. 14), Z = 2, a = 5.06870(10), b = 11.35790(10), c = 15.4004(2) Å, α = 100.5980(10)°, V = 871.47(3) Å 3 ; and R 1 = 1.61%, space group P2 1 /b11 (no. 14), Z = 2, a = 5.06720(10), b = 11.35450(10), c = 15.3941(2) Å, α = 100.5870(10)°, and V = 870.63(2) Å 3 .Minerals of the edgrewite-hydroxyledgrewite series are colorless, optically biaxial (+), 2V meas = 80(5)°; 2V calc = 78.7°; dispersion r > v, medium; orientation: Z = a, X ∧ c = 12(2)°; edgrewite: α = 1.621(2), β = 1.625(2), γ = 1.631(2); hydroxyledgrewite: α = 1.625(2), β = 1.629(2), γ = 1.635(2) (589 nm). The micro-hardness VHN 50 = 352-366 kg/mm 2 corresponds to the Mohs scale of 5.5-6. 5. FTIR spectra of edgrewite and hydroxyledgrewite show resolved bands at (edgrewite/hydroxyledgrewite, cm -1 ): 3558 and 3551 and 3543/3554, absent/3486, 1075/1075, 996/996, 980/982, 934/933, 917/918, 904/903, 890/884, 864/864, 842/842, 818/820. Raman spectra are characterized by the following bands (edgrewite/hydroxyledgrewite, cm -1 ) at: 921/923, 889/890, 839/840, and 815/814 (SiO 4 stretching), at: 556/559, 527/527, 423/419, 406/404, and 394/394 (SiO 4 bending), 309/295, 269/256, and 163/166 (CaO 6 ). In the OH stretching region three bands are noted at 3554, 3547, and 3540 cm -1 for edgrewite and two -3550 and 3475 cm -1 for hydroxyledgrewite confirming the corresponding IR spectra. The major difference in Raman and IR spectra of edgrewite and hydroxyledgrewite is the presence of two resolved peaks in the OH stretching region at ca. 3550 and 3480 cm -1 for hydroxyledgrewite.

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Crystal structure of larnite β-Ca2SiO4 and specific features of polymorphic transitions in dicalcium orthosilicate

Cited by 64 publications

References 4 publications

Sintering Characteristics of Titanium Containing Iron Ores

Sintering Characteristics of Titanium Containing Iron Ores

Utilisation of cement-asbestos wastes by thermal treatment and the potential possibility use of obtained product for the clinker bricks manufacture

Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia

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