Curriculum vitae [pdf]

Fields of scientific interest

Hydrogen and hydrous species in minerals

Crystal chemistry of trace hydrogen and hydrous species in minerals
IR spectroscopy of hydroxides and hydrates, but also nominally anhydrous minerals
Phase transitions related to proton order-disorder
Short hydrogen bonds in minerals and synthetic inorganic materials
Dynamics of hydrogen in vacancies of crystal structures

General mineralogy

Reflected light investigations of ore minerals, study of ore deposits
Surface influence and anomalous effects in mineral optics
Determination of new minerals - and discreditation of old ones
Micro-analytics of minerals (SEM, EDX)

Previous and present work

REASONS FOR OPTICAL ANISOTROPY IN CUBIC ORE MINERALS

Since the beginning of this century ore microscopists were interested in the anomalous, optically anisotropic behavior of cubic ore minerals like pyrite, cuprite, and minerals of the spinel group. The unusual effect was attributed to the influence of tectonic stress, anomalous solid solutions series, incorporation of trace elements (As in pyrite, Zn in spinels), and influence of rough preparation methods.

During the study of approximately 500 ore mineral sections (ore microscopy, XRD, SEM) the following reasons for the anomalous anisotropy were revealed:

(1) The mineral donathite (discredited) is a spinel of the chromite-magnetite (ferrite) ss-series which exhibits tiny exsolution lamellae. Because the lamellae are sub-micron sized, because they are parallel to each other, and because they have two different sets of optical constants (one relating to magnetite, the other one to chromite), they show the effect of form birefringence. Etched samples reveal the sub-micron sized lamellae with a SEM.

(2) A similar phenomenon is found in extremely fine-zoned magnetites of skarn deposits. The parallel zones of sub-micron thickness and changing composition lead also to the phenomenon of form birefringence. Etching of the polished samples with HCl makes the fine zones also visible in the SEM.

(3) A careful examination of hundreds of pyrite, spinel, and cuprite sections which had been polished with diamond pastes, showed that they were optically anisotropic without exception. (The very strong anisotropy in cuprite had been used over decades as a determinative feature!) An investigation of the polished surfaces with the electron channeling pattern (ECP) technique on a SEM proved that the upper, polished surface layers were destroyed. The application of alkaline silica solutions in the final polishing process (a chemo-mechanical method) lead to optically isotropic sections and to undistorted surface layers in the ECPs. Examination of differently oriented polished sections revealed that the surface deformation by mechanical (diamond) polishing methods is related to the surface symmetry of the sections.

Related papers:

Libowitzky E (1991) Donathite: An intergrowth of magnetite and chromite, causing form birefringence. N Jb Miner Mh 10, 449-456

Libowitzky E (1993) Ursachen optischer Anisotropieeffekte in kubischen Erzmineralen. Berichte der DMG 1, 1993 (Add Vol Eur J Mineral 5), M-P-10,79, 246, abstract

Libowitzky E (1994) Anisotropic pyrite: A polishing effect. Phys Chem Minerals, 21, 97 - 103

Libowitzky E (1994) Optical anisotropy of cuprite caused by polishing. Can Mineral, 32, 353 - 358

Libowitzky E (1994) Optical anisotropy in the spinel group: A polishing effect. Eur J Mineral, 6, 187 -194

Libowitzky E (1994) Optical anisotropy of zoned magnetites due to form birefringence. Mineral Petrol, 52, 107 - 111

Burns PC, Hawthorne FC, Libowitzky E, Bordes N, Ewing RC (1997) Donathite discredited: A mixture of two spinels. N Jb Mineral Mh, 1997, 163-174

Libowitzky E (2001) The pseudo-biabsorption of trigonal rock-forming carbonates. N Jb Miner Mh, 2001, 67 - 79

HYDROUS SPECIES IN MINERALS

Hydrogen, as a major or trace constituent of minerals, has considerable influence on the physical properties of rocks and minerals (deformation behavior, rheology, conductivity). Hydrogen occurs usually in the form of OH groups or water molecules in minerals. If H containing minerals are stable to high temperatures and pressures, they may provide an important source of hydrogen in the Earth's interior. Hence, trace amounts of water in minerals like olivine, perovskite, pyroxenes, and garnets, as well as the behavior of the stoichiometric OH and water groups in the high-pressure mineral lawsonite are of interest. In addition, the features of hydrous species in oxide and silicate structures is important for technically applied materials like the microporous zeolites, precursors of ceramics, and proton conductors.

IR spectroscopy provides one of the most sensitive methods in determining hydrogen in minerals. Using polarized radiation and oriented crystal sections the orientation of O-H vectors in the structure can be determined, and even quantitative information can be obtained by accurate measurements and calibration procedures. Additional information on the behavior of OH and water molecules (if present in larger amounts) can be gained from other spectroscopic techniques (e.g. proton-NMR) and from X-ray and neutron diffraction.

(1) FTIR investigations of pure Mg-olivine (forsterite) revealed that trace amounts of hydrogen are incorporated in the form of OH defects which are related to Si vacancies. The polarized IR spectra show several sharp bands between 3500 and 3700 cm^-1 which indicate different OH vector directions (predominantly II x) and additional trace elements in the coordination sphere of the OH groups.

(2) A similar mechanism was observed in CaTiO₃ perovskite. The FTIR spectrum shows only two bands in the OH stretching region (around 3300 cm^-1) which are indicative for OH incorporation in connection with a vacant Ca site. The stretching frequencies are in good agreement with a distorted environment around the vacancy. The type of OH defect is very similar to that of high-pressure MgSiO₃ perovskite.

The room-temperature structure of lawsonite - The arrow indicates the hopping motion (dynamic disorder) of the water molecule

(3) Single-crystal X-ray diffraction of lawsonite, CaAl₂[Si₂O₇](OH)₂.H ₂O, revealed low-temperature phase transitions from space group Cmcm (at room-temperature) to Pmcn (between 273 and 150 K), and finally P2₁cn (below 150 K). The transitions are characterized by the apparent rotation of both hydroxide and water groups, thus lowering the symmetry in two steps. The apparent rotations are accompanied by the formation of a cooperative H bond system.

The phase transitions were monitored by distinct X-ray reflections. They cause also nonlinearities in lattice parameters and optical constants.

An FTIR spectroscopic investigation of oriented lawsonite slabs resulted in a good correlation between band positions, H bond lengths, and OH vector directions at low temperatures. However, the smooth change of the spectra, the strong shift of absorption bands, and the unstable position of the water molecule between two proton acceptors, indicate rather a dynamic order-disorder transition than a displacive phase transition. These results are also confirmed by preliminary proton NMR and neutron diffraction studies.

The lawsonite-type mineral hennomartinite shows similar phase transitions at elevated temperatures. However, multiple disorder and twinning, as well as a monoclinic distortion at room-temperature (after a tempering process) draw a more complicated picture.

The water molecule and hydroxide groups in the channel of the hemimorphite structure

(4) Knowledge about lawsonite and about features of dynamic proton order-disorder and related phase transitions led also to the discovery of proton disorder and a phase transition at 98 K in hemimorphite, Zn₄[Si₂O₇](OH)₂ · H₂O. IR bands showed also a smooth development and strong band shifts with changing temperature. In addition, more bands than expected were observed in the polarized spectra. In a neutron study, the hydroxide proton revealed smeared anisotropic displacement parameters, and the environment of this H atom showed also two possible proton acceptors. A Time-of-Flight neutron single-crystal diffraction study at low temperatures revealed that the low-temperature phase is characterized by a superstructure with doubled b and c lattice parameters. Thus, freezing of the dynamically disordered H atoms leads to an ordered H atom arrangement along the ordered structural channels in hemimorphite. The ordered proton positions are in agreement with the obtained IR spectra.

Structures of MnOOH: Manganite and groutite

(5) Polarized IR spectroscopic investigations of single-crystals of MeOOH (Me = Al, Fe, Mn) minerals showed similar spectra of all substances, the O-H stretching energies, however, are different and in good agreement with the respective hydrogen bond lengths. In addition, the in-plane and out-of-plane bending modes were observed. Peculiar absorption features in the spectra between the stretching mode and the bending modes were assigned to the anharmonicity-resonance enhanced overtones of the bending modes. Increasing anharmonicity leads to increased intensity of the mentioned band(s) and is related with decreasing hydrogen bond lengths.

The broad OH absorption band in the IR spectrum of serandite

(6) Polarized infrared (IR) absorption spectra of oriented single-crystal slabs of mozartite CaMn³⁺O[SiO₃(OH)], pectolite NaCa₂[Si₃O₈(OH)], serandite NaMn₂[Si₃O₈(OH)], and members of the natrochalcite series (Na_1-xK_x)Cu₂(H₃O ₂)[SO₄]₂ (x = 0, 0.5, 1), which contain very strong hydrogen bonds due to very short O···O distances (2.44 - 2.50 Å), show broad absorption bands parallel to the respective O-H vector directions in the structures. These bands which start below 3500 cm^-1 show their approximate maxima between 1000 to 1500 cm^-1, which is in agreement with literature data on very strong H bonds. They interfere with sharp absorption bands of silicate and sulfate vibrations, and typically show "transmission windows" which are well known from spectra of organic materials with comparably short H bonds.

IR calibration line based on stoichiometric mineral hydrates and hydroxides

(7) IR spectroscopy is a useful tool also for the quantitative characterization of hydrous species in minerals. If proper experimental conditions are followed (polarized spectra of oriented or orthogonal crystal sections in cases of anisotropic crystals; knowledge about polarizer extinction ratios), the Beer-Lambert law (A = ·c ·t), which relates absorbance (A), concentration (c), and thickness (t) by the molar absorption coefficient (), may be used for the determination of water in geological materials. The molar absorption coefficient, however, can only be determined by calibration on standard materials with known water concentration. Experiments with different stoichiometric mineral hydrates and hydroxides confirmed that only the integrated absorbance A_i (band area) can be used among different materials. Further, a direct correlation between absorbance and water concentration fails, because the absorption coefficient is strongly dependent on hydrogen bond strengths. Hence, the resulting calibration line is expressed in relation to band energies () by: _i [cm^-2 per mol H₂O / L] = 246.6 · (3753 - [cm^-1]), regression coefficient r² 0.98.

(8) The frequency of an O-H stretching vibration is a valuable measure for the strength of a hydrogen bond. It is correlated to H bond lengths, i.e. O-H, O···O and H···O distances: The high-energy end is represented by very weak H bonds with d_(O···O) 3.0 Å and at 3500 - 3700 cm^-1, the low-energy end is found at very strong H bonds with d_(O···O) even below 2.5 Å and bands at 700 - 1500 cm^-1. Whereas previous d - correlation diagrams were limited either by insufficient number of data or by restricted data range, a recent d - correlation in minerals uses 125 d_(O···O)- and 47 d(H···O)-data pairs from silicates, oxi-hydroxides, sulphates, etc. containing OH, H₂O or H₃O₂ units with wavenumbers between 1000 and 3700 cm^-1. A correlation function is established in the form = 3592 - 304·10⁹ · exp(-d_(O···O) / 0.1321), R² = 0.96. Scatter of data is mainly caused by deviation from straight H bonds (avoided if d_(H···O) data are used) and cationic effects.

Correlation of O-H stretching frequency and d_(O···O) in minerals

Related papers:

Armbruster T, Libowitzky E, Diamond L, Auernhammer M, Bauerhansl P, Hoffmann C, Irran E, Kurka A, Rosenstingl H (1994) Crystal chemistry and optics of bazzite from Furkabasistunnel (Switzerland). Mineral Petrol, 52, 113 - 126

Libowitzky E, Beran A (1994) OH-Defekte in Forsterit. Mitt Österr Miner Ges, 139, 331 - 333. Abstract.

Libowitzky E, Beran A (1995) OH-defects in forsterite. Phys Chem Minerals, 22, 387 - 392

Libowitzky E, Armbruster T (1995) Low-temperature phase transitions and the role of hydrogen bonds in lawsonite. Am Mineral, 80, 1277 - 1285

Libowitzky E, Armbruster A (1996) Lawsonite-type phase transitions in hennomartinite, SrMn₂[Si₂O₇](OH)₂·H ₂O. Am Mineral, 81, 9 - 18

Beran A, Libowitzky E, Armbruster T (1996) A single-crystal infrared spectroscopic and X-ray investigation of an untwinned San Benito perovskite. Can Mineral, 34, 803 - 809

Libowitzky E, Rossman GR (1996) Principles of quantitative absorbance measurements in anisotropic crystals. Phys Chem Minerals, 23, 319 - 327

Libowitzky E, Rossman GR (1996) FTIR spectroscopy of lawsonite between 82 and 325 K. Am Mineral, 81, 1080 - 1091

Kozlova SG, Gabuda SP, Armbruster T, Libowitzky E (1996) Hydrogen atom localization in lawsonite using single-crystal PMR data. IUCR-1996 abstract

Libowitzky, E (1996) Order-disorder phase transitions in lawsonite and hemimorphite. Mitt ÖMG, 141, 132 - 133, abstract

Libowitzky, E (1996) Single-crystal IR spectroscopy of MeO(OH) minerals (Me = Al, Fe, Mn). Mitt ÖMG, 141, 134 - 135, abstract

Libowitzky E (1996) Proton disorder, phase transitions, and IR spectroscopy in minerals. EMSM, Kiev, abstract

Beran A, Libowitzky E (1996) OH-groups in natural perovskite - An IR spectroscopic study. Phase Transitions, 58, 211 - 215

Nyfeler D, Hoffmann C, Armbruster T, Kunz M, Libowitzky E (1996) Orthorhombic Jahn-Teller distortion and Si-OH in mozartite CaMn³⁺O[SiO₃OH], due to topological stress: A structure modeling, single-crystal X-ray, and FTIR study. Mitt ÖMG, 141, 168 - 169, abstract

Libowitzky E (1997) Wasserstoff-Unordnung und Phasenumwandlungen in Lawsonit und Hemimorphit. Habilitationsschrift, Universität Wien

Libowitzky E, Rossman GR (1997) IR spectroscopy of hemimorphite between 82 and 373 K and optical evidence for a low-temperature phase transition. Eur J Mineral, 9, 793-802

Libowitzky E, Kohler T, Armbruster T, Rossman GR (1997) Proton disorder in dehydrated hemimorphite - IR spectroscopy and X-ray structure refinement at low and ambient temperatures. Eur J Mineral, 9, 803-810

Kohler T, Armbruster T, Libowitzky E (1997) Hydrogen bonding and Jahn-Teller distortion in groutite, α-MnOOH, and manganite, γ-MnOOH, and their relations to ramsdellite, α-MnO₂, and pyrolusite, β-MnO₂. J Solid State Chem, 133, 486-501

Libowitzky E, Rossman GR (1997) Infrared spectroscopy: A quantitative approach to water in minerals. Ber DMG - Beih Eur J Mineral, 9, 222, abstract

Libowitzky E, Armbruster T, Beran A, Giester G, Hammer VMF, Hoffmann C, Kunz M, Nyfeler D, Rossman, GR (1997) Infrared spectroscopy of very strong hydrogen bonds in minerals. Ber DMG - Beih Eur J Mineral, 9, 221, abstract

Nyfeler D, Hoffmann C, Armbruster T, Kunz M, Libowitzky E (1997) Orthorhombic Jahn-Teller distortion and Si-OH in mozartite CaMn³⁺O[SiO₃OH]: A single-crystal X-ray, FTIR, and structure modeling study. Am Mineral, 82, 841-848

Libowitzky E, Rossman GR (1997) An IR absorption calibration for water in minerals. Am Mineral, 82, 1111-1115

Libowitzky E, Beran A (1997) Hydrogen and hydrogen bonds in minerals. XIIth Conference "Horizons in Hydrogen Bond Research". Abstract

Beran A, Giester G, Libowitzky E (1997) The hydrogen bond system in natrochalcite-type compounds - An FTIR spectroscopic study of the H₃O₂⁻ unit. Mineral Petrol, 61, 223-235

Hammer VMF, Libowitzky E, Rossman GR (1998) Single-crystal IR spectroscopy of very strong hydrogen bonds in pectolite, NaCa₂[Si₃O₈(OH)], and serandite, NaMn₂[Si₃O₈(OH)]. Am Mineral, 83, 569-576

Libowitzky E, Schultz AJ, Young DM (1998) The low-temperature structure and phase transition of hemimorphite, Zn₄Si₂O₇(OH)₂ · H₂O. Z Krist, 213, 659-668

Libowitzky E (1998) Wasserstoff und Wasserstoffbrücken in Mineralen. Mitt ÖMG, 143, 41 - 53

Armbruster T, Birrer J, Libowitzky E, Beran A (1998) Crystal chemistry of Ti-bearing andradites. Eur J Mineral, 10, 907 - 921

Libowitzky E (1998) OD-Charakter der Hemimorphitstruktur bei 20 K: Strukturuntersuchung mit TOF-Neutronen. Mitt ÖMG, 143, 332 - 333, abstract

Lager GA, Libowitzky E, Schultz AJ (1998) Neutron diffraction study of the low-temperature phase transitions in lawsonite. IMA98, A99, abstract

Libowitzky E (1999) Correlation of O-H stretching frequencies and O-H···O hydrogen bond lengths in minerals. Mh Chemie, 130, 1047 - 1059

Beran A, Libowitzky E (1999) IR spectroscopy and hydrogen bonding in minerals. In: Wright K, Catlow R (eds) (1999) Microscopic properties and processes in minerals. Kluwer Academic Publishers, Netherlands , 493 - 508

Libowitzky E (1999) Comparison of hydrogen bond distance - frequency correlations in solids. Ber. DMG - Beih Eur J Mineral, 11, abstract, in press

Hertweck B, Libowitzky E, Giester G (1999) Phase transitions in leonite-type compounds. Ber. DMG - Beih Eur J Mineral, 11, 104. Abstract

Sondergeld P, Schranz W, Kityk AV, Carpenter MA, Libowitzky E (2000) Ordering behaviour of the mineral lawsonite. Phase Transitions, Part B, 71, 189 - 203

Sondergeld P, Schranz W, Tröster A, Carpenter MA, Libowitzky E, Kitijk AV (2000) Optical, elastic, and dielectric studies of the phase transitions in lawsonite. Phys Rev B, 62, 6143 - 6147

Libowitzky E (2000) Phase transitions in minerals: Correlation of spectroscopic and diffraction data. 19^th Eur Cryst Meeting Astracts, 137. Abstract

Libowitzky E, Giester G (2000) The crystal structure of soda at 110 K and 270 K. 19^th Eur Cryst Meeting Astracts, 341. Abstract

Hertweck B, Armbruster T, Libowitzky E (2000) A single-crystal study of the low-temperature phase transitions in leonite-type compounds. 19 th Eur Cryst Meeting Astracts, 362. Abstract

Armbruster T, Kohler T, Libowitzky E, Friedrich A, Miletich R, Kunz M, Medenbach O, Gutzmer J (2001) Structure, compressibility, hydrogen bonding, and dehydration of the tetragonal Mn 3+ hydrogarnet, henritermierite. Am Mineral, 86, 147 - 158

Hertweck B, Libowitzky E (2001) IR and Raman spectroscopy of the phase transitions in leonite-type compounds. Bull Liaison SFMC, 13, 80. Abstract

Hertweck B, Libowitzky E, Schultz AJ (2001) Neutron diffraction study of the low-temperature phase transitions of Mn-leonite. Mitt Österr Miner Ges, 146, 109 - 110. Abstract

Hertweck B, Libowitzky E, Giester G (2001) The crystal structures of the low-temperature phases of leonite-type compounds, K₂Me(SO₄)₂×4H₂O (Me²⁺ = Mg, Mn, Fe). Am Mineral, 86, 1282 - 1292

Nasdala L, Beran A, Libowitzky E, Wolf D (2001) The incorporation of hydroxyl groups and molecular water in natural zircon (ZrSiO₄), Am J Sci, 301, 831 - 857

Szalay V, Kovács L, Wöhlecke M, Libowitzky E (2002) Stretching potential and equilibrium length of the OH bond in solids. Chem Phys Lett, 354, 56 - 61

Hertweck B, Armbruster T, Libowitzky E (2002) Multiple phase transitions of leonite-type compounds: optical, calorimetric, and X-ray data. Mineral Petrol, 75, 245 - 259

Libowitzky E(2002) Hydrogen bonding in minerals and inorganic materials. SGK/SSCr Newsletter, 56 and 57, 7. Abstract

Hertweck B, Libowitzky E (2002) Vibrational spectroscopy of phase transitions in leonite-type minerals. Eur J Mineral, 14, 1009 - 1017

Beran A, Libowitzky E (2003) IR spectroscopic characterization of OH defects in mineral phases. Phase Trans, 76, 1 - 15

Halmer MM, Libowitzky E, Beran A (2003) IR spectroscopic determination of OH defects in spinel group minerals. Geophys Res Abstr, 5, 06742. Abstract

Libowitzky E , Giester G (2003) Washing soda (natron), Na₂CO₃×10H₂O, revised: Crystal structures at low and ambient temperatures. Mineral Petrol, 77, 177 - 195

Giester G, Libowitzky E (2003) Crystal structures and Raman spectra of Cu(OH)F and Cu₃(OH)₂F₄. Z Kristallogr, 218, 351 - 356

Libowitzky E (2003) Hydrogen and hydrogen bonds in minerals. Book of Abstracts, 46, LERM 2003, Nove Mesto (CZ). Abstract

Halmer MM, Beran A, Libowitzky E (2003) Detecting OH defects in iron-bearing ( ^IVFe²⁺) spinel phases by IR spectroscopy. Book of Abstracts, 27, LERM 2003, Nove Mesto (CZ). Abstract

Hertweck B, Libowitzky E, Schultz AJ(2003) The hydrogen bond system of Mn-leonite: neutron diffraction results in comparison with IR spectroscopic data. Z Kristallogr, 218, 403 - 412

Halmer MM, Libowitzky E, Beran A (2003) IR spektroskopische Untersuchungen von OH-Defekten in eisenhaltigen ( ^IVFe²⁺) Spinellphasen. Mitt Österr Miner Ges, 148, 156. Abstract

Libowitzky E, Beran A (2004) IR spectroscopic characterisation of hydrous species in minerals. In: Beran A, Libowitzky E (eds) (2004) "Spectroscopic Methods in Mineralogy", EMU Notes in Mineralogy 6, 227 - 279

Beran A, Libowitzky E (eds) (2004) "Spectroscopic Methods in Mineralogy", EMU Notes in Mineralogy 6, 661 pp

Mihajlovic T, Libowitzky E, Effenberger H (2004) Synthesis, crystal structure, infrared and Raman spectra of Sr 5(As 2O 7) 2(AsO 3OH). Mitt Österr Miner Ges 149, 67. Abstract

Bellatreccia F, Della Ventura G, Libowitzky E, Beran A, Ottolini L (2004) A calibration curve for the OH content in vesuvianite: a polarized single-crystal FTIR study. Mitt Österr Miner Ges 149, 14. Abstract

Bellatreccia F, Della Ventura G, Libowitzky E, Beran A (2004) The quantitative determination of B and H in vesuvianite: an FTIR spectroscopic study. 32 nd Int Geol Congress, Florence , G04.02. Abstract

Mihajlovic T, Libowitzky E, Effenberger H (2004) Synthesis, crystal structure, infrared and Raman spectra of Sr 5(As 2O 7) 2(AsO 3OH). J Solid State Chem, in press

Bellatreccia F, Della Ventura G, Ottolini L, Libowitzky E, Beran A (2004) The quantitative analysis of OH in vesuvianite: a polarized FTIR and SIMS study. Phys Chem Minerals, submitted