Evgeny V. Galuskin

Vibrational spectra of phosphate–silicate biomaterials

Abstract For substitutive and reconstruction surgery different classes of materials (e.g. metals, polymers, ceramics composites) as implant materials are employed. Among them the ceramics as potentially biologically active materials seem to be most promising for further applications. In presented work the oxide ceramic materials in the Na 2 O–CaO–Al 2 O 3 –P 2 O 5 –SiO 2 system were obtained. The materials in the glass, glass–ceramics and crystalline form were studied. With IR and Raman spectroscopy the phase composition of these materials was found. With vibrational spectroscopy methods the glassy or crystalline state can be recognized. The short-range structural order of the glass phase was determined also. The most interesting results concern the glass–ceramics materials whose chemical and phase composition indicates its potential biological activity and good enough mechanical properties.

Lakargiite CaZrO3: A new mineral of the perovskite group from the North Caucasus, Kabardino-Balkaria, Russia

Abstract Lakargiite CaZrO3-the zirconium analog of perovskite [Pbnm, a = 5.556(1), b = 5.715(1), c = 7.960(1) Å, V 252.7(1) Å3, Z = 4]-was discovered as an accessory mineral in high-temperature skarns in carbonate-silicate rocks occurring as xenoliths in ignimbrites of the Upper-Chegem (Verkhniy Chegem) volcanic structure, the North Caucasus, Kabardino-Balkaria, Russia. Lakargiite forms pseudo-cubic crystals up to 30-35 μm in size and aggregates up to 200 μm. Lakargiite is associated with spurrite, larnite, calcio-olivine, calcite, cuspidine, rondorfite, reinhardbraunsite, wadalite, perovskite, and minerals of the ellestadite group. The new perovskite mineral belongs to the ternary solid solution CaZrO3-CaTiO3-CaSnO3 with a maximum CaZrO3 content of ca. 93%, maximum CaTiO3 content of 22%, and maximum CaSnO3 content of 20%. Significant impurities are Sc, Cr, Fe, Ce, La, Hf, Nb, U, and Th. Raman spectra of lakargiite are similar to those of the synthetic phase Ca(Zr,Ti)O3 with strong bands at 352, 437, 446, 554, and 748 cm-1. Lakargiite crystallized under sanidinite-facies conditions of contact metamorphism characterized by very high temperatures and low pressures.

Chegemite Ca7(SiO4)3(OH)2 – a new humite-group calcium mineral from the Northern Caucasus, Kabardino-Balkaria, Russia

The new mineral chegemite Ca7(SiO4)3(OH)2 ( Pbnm , Z = 4)1, a = 5.0696(1), b = 11.3955(1), c = 23.5571(3) A; V = 1360.91(4) A3 – the calcium and hydroxyl analogue of humite – was discovered as a rock-forming mineral in high-temperature skarns in calcareous xenoliths in ignimbrites of the Upper Chegem volcanic structure, Northern Caucasus, Kabardino-Balkaria, Russia. The chegemite forms granular aggregates with grain sizes up to 5 mm and is associated with various high-temperature minerals: larnite, spurrite, rondorfite, reinhardbraunsite, wadalite, lakargiite, and srebrodolskite, corresponding to the sanidinite metamorphic facies. The empirical formula of the holotype chegemite (mean of 68 analyses) is Ca7(Si0.997Ti0.003O4)3(OH)1.48F0.52. Chegemite is characterized by the following optical properties: 2VZ = −80(8)°, α = 1.621(2), β = 1.626(3), γ = 1.630(2); Δ = 0.009; density D calc = 2.892 g/cm3. The crystal structure, including hydrogen positions, has been refined from single-crystal Mo K α X-ray diffraction data to R = 2.2 %. Octahedral Ca–O distances are similar to those of γ-Ca2SiO4 (calcio-olivine). As is characteristic of OH-dominant humite-group minerals, two disordered H positions could be resolved. The main bands in the FTIR-spectra of chegemite are at 3550, 3542, 3475, 927, 906, 865, 820, 800, 756, 705, 653, 561, 519 and 437 cm−1. Those in non-polarized Raman spectra are at 389, 403, 526, 818, 923.5, 3478, 3551 and 3563 cm−1. The X-ray diffraction powder-pattern (Fe K α-radiation) shows the strongest lines {d \[A\]( I obs)} at: 1.907(10), 2.993(8), 2.700(8), 3.015(7), 2.720(7), 2.834(6), 3.639(5), and 3.040(5).

The non-ring cations influence on silicooxygen ring vibrations

Abstract In this work IR spectra of synthetic and natural ring silicates (cyclosilicates) containing in their structure isolated silicooxygen rings of various numbers of members ( n =3,4,6) have been presented. By means of factor group analysis it has been shown that only one intensive band characteristic of ring structures (“ring band”) should be observed in the IR spectra of cyclosilicates. The ring band position is related to the number of ring members [M. Handke, M. Sitarz, W. Mozgawa, J. Mol. Struct. 450 (1998) 229] and strongly depends on the kind of non-ring cations connecting the rings. The existence of the cations such as Ti 4+ , Zr 4+ , Cu 2+ etc. in the cyclosilicates structure causes the conjugation of the vibrations, making the interpretation of the spectra more difficult. In this work we have shown that the presence of such non-ring cations causes the shifting of the “ring band” to the higher wavenumbers. In the case when Al 3+ are non-ring cations it is almost impossible to identify the “ring band” (6-membered cyclosilicates).

Vorlanite (CaU6+O4) - A new mineral from the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia

Abstract The new mineral vorlanite, (CaU6+)O4, Dcalc = 7.29 g/cm3, H = 4-5, VHN10 = 360 kg/mm2, was found near the top of Mt. Vorlan in a calcareous skarn xenolith in ignimbrite of the Upper Chegem caldera in the Northern Caucasus, Kabardino-Balkaria, Russia. Vorlanite occurs as aggregates of black platy crystals up to 0.3 mm long with external symmetry 3̄m. The strongest powder diffraction lines are [d(Å)/(hkl)]: 3.107/(111), 2.691/(200), 1.903/(220), 1.623/(311), 1.235/(331), 1.203/(420), 1.098/(422), 0.910/(531). Single-crystal X-ray study gives isometric symmetry, space group Fm3̄m, a = 5.3813(2) Å, V = 155.834(10) Å3, and Z = 2. X-ray photoelectron spectroscopy indicate that all U in vorlanite is hexavalent. The mineral is isostructural with fluorite and uraninite (U4+O2). In contrast to synthetic rhombohedral CaUO4, and most U6+ minerals, the U6+ cations in vorlanite are present as disordered uranyl ions. [8]Ca2+ and [8]U6+ are disordered over a single site with average M-O = 2.33 Å. Vorlanite is believed to be a pseudomorphic replacement of originally rhombohedral CaUO4. We assume that this rhombohedral phase transformed by radiation damage to cubic CaUO4 (vorlanite). The new mineral is associated with larnite, chegemite, reinhardbraunsite, lakargiite, rondorfite, and wadalite, which are indicative of high-temperature formation (>800 °C) at shallow depth.

Elbrusite-(Zr)—A new uranian garnet from the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia

Abstract Elbrusite-(Zr) Ca3(U6+Zr)(Fe3+2 Fe2+)O12, a new uranian garnet (Ia3̅d, a ≈ 12.55 Å, V ≈ 1977 Å3, Z = 8), within the complex solid solution elbrusite-kimzeyite-toturite Ca3(U,Zr,Sn,Ti,Sb,Sc,Nb...)2(Fe,Al,Si,Ti)3O12 was discovered in spurrite zones in skarn xenoliths of the Upper Chegem caldera. The empirical formula of holotype elbrusite-(Zr) with 25.14 wt% UO3 is (Ca3.040Th0.018Y0.001)Σ3.059(U6+0.658Zr1.040Sn0.230Hf0.009Mg0.004)Σ1.941(Fe3+1.575Fe2+0.559Al0.539Ti40.199Si0.099Sn0.025V5+0.004)Σ3O12. Associated minerals are spurrite, rondorfite, wadalite, kimzeyite, perovskite, lakargiite, ellestadite-(OH), hillebrandite, afwillite, hydrocalumite, ettringite group minerals, and hydrogrossular. Elbrusite-(Zr) forms grains up to 10-15 μm in size with dominant {110} and minor {211} forms. It often occurs as zones and spots within Fe3+-dominant kimzeyite crystals up to 20-30 μm in size. The mineral is dark-brown to black with a brown streak. The density calculated on the basis of the empirical formula is 4.801 g/cm3 The following broad bands are observed in the Raman spectra of elbrusite-(Zr): 730, 478, 273, 222, and 135 cm-1. Elbrusite-(Zr) is radioactive and nearly completely metamict. The calculated cumulative dose (α-decay events/mg) of the studied garnets varies from 2.50 × 1014 [is equivalent to 0.04 displacement per atom (dpa)] for uranian kimzeyite (3.36 wt% UO3), up to 2.05 × 1015 (0.40 dpa) for elbrusite-(Zr) with 27.09 wt% UO3.

Shulamitite Ca3TiFe3+AlO8 – a new perovskite-related mineral from Hatrurim Basin, Israel

Shulamitite, ideally Ca 3 TiFe 3+ AlO 8 , is a mineral intermediate between perovskite CaTiO 3 and brownmillerite Ca 2 (Fe,Al) 2 O 5 . It was discovered as a major mineral in a high-temperature larnite-mayenite rock from the Hatrurim Basin, Israel. Shulamitite is associated with larnite, F-rich mayenite, Cr-containing spinel, ye9elimite, fluorapatite, and magnesioferrite, and retrograde phases (portlandite, hematite, hillebrandite, afwillite, foshagite and katoite). The mineral forms reddish brown subhedral grains or prismatic platelets up to 200 μm and intergrowths up to 500 μm. The empirical formula of the holotype shulamitite (mean of 73 analyses) is (Ca 2.992 Sr 0.007 LREE 0.007 )(Ti 0.981 Zr 0.014 Nb 0.001 )(Fe 3+ 0.947 Mg 0.022 Cr 0.012 Fe 2+ 0.012 Mn 0.001 )(Al 0.658 Fe 3+ 0.288 Si 0.054 )O 8 . The X-ray diffraction powder-pattern (Mo Kα -radiation) shows the strongest lines {d [A]( I obs )} at: 2.677(100), 2.755(40), 1.940(40), 11.12(19), 1.585(17), 1.842(16), 1.559(16), 3.89 (13), 1.527(13). The unit-cell parameters and space group are: a = 5.4200(6), b = 11.064(1), c = 5.5383(7) A, V= 332.12(1) A 3 , Pmma, Z = 2. The calculated density is 3.84 g/cm 3 . The crystal structure of shulamitite has been refined from X-ray single-crystal data to R 1 = 0.029 %. No partitioning among octahedral sites was found for Ti and Fe 3+ in the structure of shulamitite, these cations are randomly distributed among all octahedra indicating an example of “valency-imposed double site occupancy”. The strong bands in the Raman spectrum of shulamitite are at: 238,250, 388,561, and 742 cm −1 . Shulamitite from the Hatrurim Basin crystallized under combustion metamorphism conditions characterized by very high temperatures (1150−1170 °C) and low pressures (high- T -region of the spurrite-merwinite facies). Chemical data for shulamitite and its Fe-analog from other metacarbonate occurrences (natural and anthropogenic) are given here.

Harmunite CaFe2O4: A new mineral from the Jabel Harmun, West Bank, Palestinian Autonomy, Israel

Abstract Harmunite, naturally occurring calcium ferrite CaFe2O4, was discovered in the Hatrurim Complex of pyrometamorphic larnite rocks close to the Jabel Harmun, the Judean Desert, West Bank, Palestinian Autonomy, Israel. The new mineral occurs in larnite pebbles of the pseudo-conglomerate, the cement of which consists of intensely altered larnite-bearing rocks. Srebrodolskite, magnesioferrite, and harmunite are intergrown forming black porous aggregates to the central part of the pebbles. Larnite, fluorellestadite, ye’elimite, fluormayenite, gehlenite, ternesite, and calciolangbeinite are the main associated minerals. Empirical crystal chemical formula of harmunite from type specimen is as follows Ca1.013(Fe3+ 1.957Al0.015Cr3+ 0.011Ti4+0.004 Mg0.003)S1.993O4. Calculated density is 4.404 g/cm3, microhardness VHN50 is 655 kg/mm2. The Raman spectrum of harmunite is similar to that of the synthetic analog. Harmunite in hand specimen is black and under reflected plane-polarized light is light gray with red internal reflections. Reflectance data for the COM wavelengths vary from ~22% (400 nm) to ~18% (700 nm). The crystal structure of harmunite [Pnma; a = 9.2183(3), b = 3.0175(1), c = 10.6934(4) Å; Z = 4, V = 297.45(2) Å3], analogous to the synthetic counterpart, was refined from X-ray single-crystal data to R1 = 0.0262. The structure of CaFe2O4 consist of two symmetrically independent FeO6 octahedra connected over common edges, forming double rutile-type ∞1[Fe2O6] chains. Four such double chains are further linked by common oxygen corners creating a tunnel-structure with large trigonal prismatic cavities occupied by Ca along [001]. The strongest diffraction lines are as follows [dhkl, (I)]: 2.6632 (100), 2.5244 (60), 2.6697 (52), 1.8335 (40), 2.5225 (35), 2.2318 (34), 1.8307 (27), 1.5098 (19). Crystallization of harmunite takes place in the presence of sulfate melt. ̃

Structural studies of the NaCaPO4-SiO2 sol-gel derived materials

Structural studies of the NaCaPO4– SiO2 materials have been carried out. Amorphous materials from this system, after controlled crystallization process, can be used as potential nanomaterials. Structural studies of nanomaterials are of fundamental importance in view their future applications. Materials of different [PO4] 32 /[SiO4] 42 tetrahedra proportion have been prepared. Na þ and Ca 2þ cations have compensated the negative charge of the lattice. Amorphous and crystalline materials have been obtained by sol – gel as well as conventional melting methods. The XRD phase identification has enabled amorphous and crystalline materials identification and suggests the separation of phosphorus and silicate crystalline phases. The obtained materials were examined using the electron scanning microscope and EDX spectrometer. Analysis of electron scanning microscope maps shows considerable inhomogeneity of crystalline samples. Fluctuations in ions distribution, in case of amorphous materials, have been noted too. DTA investigations have enabled to find the probable characteristic temperatures of glass crystallization. Detailed infrared spectroscopy measurements have been carried out. The spectra of obtained materials have been compared with the spectra of cristobalite. Spectroscopic studies confirm the inhomogeneity of materials. q 2003 Elsevier Science B.V. All rights reserved.

Vapnikite Ca 3 UO 6 a new double-perovskite mineral from pyrometamorphic larnite rocks of the Jabel Harmun, Palestinian Autonomy, Israel

Abstract The new mineral species vapnikite, Ca3UO6, was found in larnite pyrometamorphic rocks of the Hatrurim Formation at Jabel Harmun in the Judean desert, Palestinian Autonomy, Israel. Vapnikite is an analogue of the synthetic ordered double-perovskite b-Ca3UO6 and is isostructural with the natural fluorperovskite - cryolite Na3AlF6. Vapnikite Ca3UO6 (P21/n, Z = 2, a = 5.739(1), b = 5.951(1), c = 8.312(1) Å, b = 90.4(1)°, V = 283.9(1) Å3) forms yellow-brown xenomorphic grains with a strong vitreous lustre. Small grains up to 20_30 mm in size are wedged between larnite, brownmillerite and ye’elimite. Vapnikite has irregular fracture, cleavage and parting were not observed. The calculated density is 5.322 g cm-3, the microhardness is VHN25 = 534 kg mm-2 (mean of seven measurements) corresponding to the hardness of ~5 on the Mohs scale. The crystal structure of vapnikite Ca3UO6 differs from that of its synthetic analogue b-Ca3UO6 by having a larger degree of Ca, U disorder. Vapnikite formed at the high-temperature retrograde stage of pyrometamorphism when larnite rocks were altered by fluids/melts of high alkalinity.