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The thermoelastic behavior of a crystal of Fe-rich holmquistite with crystal-chemical formula A(K0.01Na0.01)B(Li1.88Mg0.10Na0.02)C(Mg1.68Fe1.422+Mn0.022+Al1.88)TSi8.00O22W[(OH)1.97F0.03] was studied by single-crystal X-ray diffraction at temperatures up to 1023 K, where isothermal annealing in air for 160 h yielded the loss of 0.85 H apfu coupled with oxidation of M1Fe. A complex pattern of cation exchanges was deciphered by comparing structure refinements done before and after annealing. Li migration from the M4 to M3 site is responsible for nonlinearity of the c parameter around 600 K during the first annealing. Cooling of the partially deprotonated crystal to room temperature (RT) showed discontinuities in trends of the b and c parameters around 820–800 K, which cannot be ascribed to a phase transition and can be explained by a rearrangement of the structural units affecting the geometry of the M4 polyhedron. Such discontinuities have never been observed in amphiboles before and must be related to dimensional constraints deriving from the peculiar composition of this amphibole, which contains the smallest possible homovalent constituents, i.e., BLi, CAl, and TSi. The calculated thermo-elastic parameters are: Fe-rich holmquistite: αa = 1.36(2)×10–5; αb = 0.55(1)×10–5; αc = 1.5(1)×10–5 – 6.7(9)×10–9; αV = 3.5(3)×10–5 – 0.8(3)×10–8 (polynomial); 2.58(6)×10–5 (linear); partially deprotonated Fe-rich holmquistite: αa = 1.324(9)×10–5 (RT-1023 K); αb = 0.60(1)×10–5 (RT-773 K); αc = 0.68(2)×10–5 (RT-773 K); αV = 2.59(2)×10–5 (RT-773 K). Fe-rich holmquistite is much stiffer than all the previously studied orthorhombic Pnma and Pnmn amphiboles. The results of this work allow progress toward a general model that may explain how the amphibole structure responds to non-ambient conditions, and allows the release of water in diverse geological environments.

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The feasibility of transforming the residues of cultivation of two rocks into secondary raw materials through the alkali activation process has been assessed. Mixtures of a sulfate-bearing kaolinitic clay (L02-K) and a sludge derived by the sewing of Pietra Serena stone (sPS) have been investigated. These materials were preliminarily treated at high temperature to improve their reactivity (heat-treated samples are hereafter labelled as L02-MK and sPS-800). Pastes were prepared with mixtures of L02-MK and sPS-800 in different weight proportions by using 8 M NaOH solutions as alkaline activator and cured at 85 °C for 24 h. Mechanical strength was determined after 1, 7 and 28 days and the reaction products were characterized by XPRD, SEM/EDX and MAS-NMR. Sulfate solubility was quantified by leaching tests. The alkali activation of the sole sulfate-bearing clay gives a material with developed mechanical strength of 4(1) MPa. Some N-A-S-H gel forms together with gibbsite and thenardite, which can be easily leached. Better results are obtained by the activation of mixtures of the two precursors, and mixed alkali cements or hybrid cements are obtained. The presence of CaO from heat-treated Pietra Serena sludge improves the mechanical strength of the resulting pastes up to 11.8(9) MPa. In this case, a mixture of gels forms, specifically, a calcium-rich gel (C-A-S-H-type) co-exists with (N,C)-A-S-H-type gel. U-phase and CAN-type zeolites also form. They trap sulfate from the clay and considerably reduce sulfate solubility. In conclusion, L02-MK and sPS-800 are promising raw materials for alkaline cements, whose properties may suggest application in soil stabilization or in waste confinement., The authors wish to thank the suppliers of the materials utilized for the present work: Eurit s.r.l. (L02 clay) and Pietra Serena Group s.r.l. (Pietra Serena). Ministero dell’Istruzione, dell’Universit` a e della Ricerca is thanked for the scholarship “Fondo per il sostegno dei giovani”. This research was also funded by the Spanish Ministry of Science and Innovation under research project PID2019-111464RB-I00, and by the Italian Ministry of Economic Development (D.M. 5 March 2018—CHAPTER II—Call for Research and Development Projects within the application areas consistent with the National Strategy of Intelligent Specialization [SNSI]—Smart Factory), under the Project I.E.S.MAN. (Internet of Enterprise Sustainable Manufacturing) n. 211.

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In the MgxCu1 − xCr2O4 solid solution, progressive substitution of the Jahn–Teller and d 9 Cu2+ cation with the spherical and closed-shell Mg2+ cation results in a gradual reduction of the splitting of a and c unit-cell parameters, until transformation occurs from the tetragonal I41/amd to the cubic archetype spinel structure. Tetragonal members of the series transform to cubic at high temperature, and the transition temperature decreases with increasing Mg content. The phase transition is first order in character for Cu-rich samples and evolves towards second-order character at intermediate compositions., Temperature and composition dependences of the I41/amd → phase transition in the MgxCu1 − xCr2O4 spinel solid solution, due to the melting of the cooperative Jahn–Teller distortion, have been studied by means of single-crystal X-ray diffraction. Crystals with x = 0, 0.10, 0.18, 0.43, 0.46, 0.53, 1 were grown by flux decomposition methods. All crystals have been refined in the tetragonal I41/amd space group except for the Mg end-member, which has cubic symmetry. In MgxCu1 − xCr2O4 the progressive substitution of the Jahn–Teller, d 9 Cu2+ cation with spherical and closed-shell Mg2+ has a substantial effect on the crystal structure, such that there is a gradual reduction of the splitting of a and c unit-cell parameters and flattening of the tetrahedra. Single-crystal diffraction data collected in situ up to T = 1173 K show that the tetragonal-to-cubic transition temperature decreases with increasing Mg content. The strength of the Cu—Cu interaction is, in effect, modulated by varying the Cu/Mg ratio. Structure refinements of diffraction data collected at different temperatures reveal that heating results in a gradual reduction in the tetrahedron compression, which remains significant until near the transition temperature, however, at which point the distortion of the tetrahedra rapidly vanishes. The spontaneous strain arising in the tetragonal phase is large, amounting to 10% shear strain, e t, and ∼ 1% volume strain, V s, in the copper chromite end-member at room temperature. Observed strain relationships are consistent with pseudoproper ferroelastic behaviour ( ∝ V s ∝ , where q JT is the order parameter). The I41/amd → phase transition is first order in character for Cu-rich samples and then evolves towards second-order character. Although a third order term is permitted by symmetry in the Landau expansion, this behaviour appears to be more accurately represented by a 246 expansion with a change from negative to positive values of the fourth-order coefficient with progressive dilution of the Jahn–Teller cation.

The crystal structure of duftite, PbCu(As()4)(OI I), has been re-evaluated on the basis of X-ray diffraction data from a single crystal from Grube Clara, Germany. Duftite is orthorhombic with a=7.7668(4), 6 = 9.2005(5), c= 5.9878(3) A; V = 427.88(4) A3, non-centrosymmetric space group P2x2x2h Z= 4. The structure refinement converges to a final R1 value of 0.0174 for 1252 reflections and allows an accurate description of the crystallographic features. The results obtained on the natural sample are compared with those available in the literature for this phase, regarding its synthetic counterpart. The crystal structure of duftite is confirmed and this work reports the first full anisotropic crystal structure refinement for this mineral, with the position of the hydrogen atom determined from the final AFmap. Duftite is a member of the adelite-descloizite group with the Cu2+ Jahn-Teller active cation in distorted octahedral coordination. Individual bond lengths and other geometrical parameters are compared with those of other arsenates of this group.

Alkali activated materials, and geopolymers in particular, have proven to be a valid alternative to traditional binders, due to their significant mechanical performances, durability and environmental advantages. The present paper describes the results of a research project, initiated in order to explore the potentiality and suitability of metakaolin-based geopolymers within the domain of cultural heritage. SEM-EDS analyses were utilized in order to evaluate the interaction of geopolymers with natural and artificial stones by assessing the variations at the boundaries due to differences in the minero-petrographic and chemical compositions of natural and artificial stones. Three ornamental stones widely used in the historic Italian architecture were selected: Pietra Serena (sandstone), Pietra di Angera (dolostone) and Pietra di Noto (limestone). Widespread construction materials, such as concrete and brick were also included in the study. Furthermore, the interaction between geopolymers and historic elements, such as decorative stones and/or mortars, were also studied, in order to evaluate a possible application of these materials within the realm of restoration, as well as for the conservation of historic manufactures. The results revealed that adhesion appears to be satisfactory in the case of all analyzed materials. Silicoaluminate phases partially dissolve and increase the availability of Si and Al within the interface, resulting in a strongly interlinked whole, whereas carbonate phases and rocks supply Ca, which changes the local composition of the binder.

Potentialities and suitability of metakaolin-based geopolymers in Cultural Heritage have been explored. In particular, in order to evaluate their possible use as restoration materials in conservation of historic manufactures, mortars have been prepared by adding aggregates of Italian ornamental stones to alkali-activated metakaolin with binder/sand ratio of 1:1. To improve workability, geopolymer binders have been synthesized from metakaolin and sodium silicate solution with water/solid weight ratios between 0.33 and 0.66 and SiO 2 /Al 2 O 3 and Al 2 O 3 /Na 2 O molar ratios of 3.70 and 1.04, respectively, and characterized by several techniques, including mechanical strength tests according to UNI EN 196-1. All binders display good mechanical properties, with compressive and flexural strength values as high as 72 MPa and 6 MPa, respectively, and decreasing with increasing water/solid ratio. The increase of water in geopolymer formulation has little negative effect on the aluminosilicate gel development and on the strength of these materials. Mortars display a homogeneous and compact matrix, bonded (silicoaluminate aggregates) or interlocked (carbonate) with aggregates. Their compressive strengths fall in the masonry mortars class M20 range. Their pore size distribution guarantees good breathability and adaptability to the substrate. The final materials mimic the original stones, with good aesthetic compatibility.

Structural modifications with temperature of adamite, Zn-2(AsO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and collapse of the crystal structure. In the temperature range 25-400 degrees C, adamite shows positive and linear expansion. Axial thermal expansion coefficients, determined over this temperature range, are alpha(a) = 1.06(2) x 10(-5) K-1, alpha(b) = 1.99(2) x 10(-5) K-1, alpha(c) = 3.7(1) x 10(-6) K-1 and alpha(V) = 3.43(3) x 10(-5) K-1. Axial expansion is then strongly anisotropic with alpha(a):alpha(b):alpha(c) = 2.86: 5.38 : 1. Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the adamite structure accommodates variations in temperature. Expansion is limited mainly by edge sharing Zn(2) dimers along a and by edge sharing Zn(1) octahedra chains along c; on the other hand, connections of polyhedra along b, the direction of maximum expansion, is governed by corner sharing. Increasing temperature induces mainly an axial expansion of Zn(1) octahedron, which becomes more elongated, and no significant variations of the Zn(2) trigonal bipyramids and As tetrahedra. Starting from 400 degrees C, deviation from a linear evolution of unit-cell parameters is observed, associated with some deterioration of the crystal, a sign of incipient dehydration. The process leads to the formation of Zn-4(AsO4)(2)O.y

The feasibility of using kaolins activated at T = 550 degrees C to synthesize geopolymers has been assessed, opening the way for utilizing low-grade kaolins containing sulfates. The effects of temperature (in the range 40-90 degrees C) and time (in the range 1-19 h) of curing, as well as of a secondary drying treatment on compressive strength and linear shrinkage of geopolymers have been studied by experimental design technique using a high-quality kaolin as starting material. Geopolymers characterized by high strength (>60 MPa) and low shrinkage (

ECS1@IYCr2014: Conveying a vision of modern crystallography Roberta Oberti, Serena Tarantino, Michele Zema, Marco Milanesio, Rita Berisio, Anna Moliterni, Carlo Mealli The first edition of the ECA European Crystallography School (ECS1), to be held in Pavia (Italy) during the course of IYCr2014, has found good balance between two apparently diverging goals: (i) to help students and young researchers to find their way in modern science, while keeping a special focus on the molecular and crystalline structure to interpret properties and functionality of materials; (ii) to raise the social and academic awareness of the great advances that crystallography has allowed and will allow to many branches of sciences. Students may choose between two formulae, i.e. a 6-day course with lectures and hands-on sessions held by renowned scientists, covering the state-of-the-art of crystallographic methods, theories and applications, at the same time indicating their future perspectives and cutting-edge aspects, or a 10-day Erasmus Intensive Programme, including a 3-day preparatory course and granting 3 ECTS credits. IYCr2014 is a unique opportunity to stimulate and ignite widespread interest in crystallography; therefore, some frontier seminars will be open to University faculty members, students, and to the general public. Efforts will be made to create a nice and friendly environment, with the goal to provide chances for future collaborations. Students will be invited to bring a poster showing their research results, projects or scientific interests. This will allow students to discuss their ideas with experienced crystallographers and favour aggregation. The programme received good support from scientific institutions and vendors, and a great response from the students: more than 110 pre-registrations from 33 countries were already received at the time this abstract was prepared, showing that there is a real need for both fundamental and advanced teaching in crystallography. We hope that this format will be continued and improved so as to provide a stable, periodic rendezvous for students and researchers under the common theme of crystallography.

The mechanism of the intracrystalline cation exchange reaction in a natural columbite sample from Kragero, with composition (Mn0.85Fe0.15)(Nb1.8Ta0.2)O6, has been characterised by means of TEM and HR synchrotron-radiation powder diffraction. In columbite, cations may occupy two different octahedral sites, with divalent cations preferring the A site and pentavalent cations preferring the B site. When both the octahedral sites are randomly occupied, columbite adopts a α-PbO2-type crystal structure; ordering of divalent cations on A sites and pentavalent cations on B sites gives rise to an ...ABBABB… sequence along the a direction resulting in a tri-α-PbO2-type structure in which the Pbcn symmetry is maintained. The completely ordered scheme represents the only thermodynamically stable state. Nevertheless, partially disordered distributions of cations among the sites are often found in natural samples. High temperature treatment of these samples leads to the completely ordered state [1, 2]. Two single crystals with different degrees of order obtained by quenching experiments were prepared for TEM study. They revealed a pervasive presence of nano-sized domains with rhombic shape and sides parallel to (310) planes. Diffraction contrast images and high resolution images clearly show that rhombic domains are ordered and dispersed in a disordered matrix. In situ high temperature powder diffraction data collected at ESRF ID31 starting from untreated powders (degree of cation order Q ~ 0.15) and until completion of the ordering process shows that the sluggish cation ordering process in columbite is more complicated than the simple picture which is deducible from laboratory X-ray diffraction studies. The diffraction patterns show split reflections and require analysis using two distinct columbite phases with different degrees of order. The phase characterised by a higher Q value has slightly broader peak profiles. This is consistent with TEM observations of some small ordered domains in a largely disordered material. Furthermore the size of these ordered domains in the starting material, as derived by peak-profile analysis, is also consistent with TEM observations. Preliminary Rietveld analyses exclude a nucleation and growth model followed by coarsening of the domains, and indicate two stages for the cation ordering mechanism: a first stage in which the degree of order increases and the domains size remains nearly constant and a second one in which the growth of the domains accompanies the achievement of the complete cation order. PDF (Pair Distribution Function) analysis of patterns collected at different Q will allow to give further insights and a better understanding of the factors controlling the columbite ordering process.

The thermoelastic behaviour of a natural gedrite having the crystal-chemical formula Na-A(0.47) (B)(Na-0.03 Mg-1.05 Fe (0.86) (2+) Mn-0.02 Ca-0.04) (C)(Mg-3.44 Fe (0.36) (2+) Al-1.15 Ti (0.05) (4+) ) (T)(Si-6.31 Al-1.69)O-22 (W)(OH)(2) has been studied by single-crystal X-ray diffraction to 973 K (Stage 1). After data collection at 973 K, the crystal was heated to 1,173 K to induce dehydrogenation, which was registered by significant changes in unit-cell parameters, M1-O3 and M3-O3 bond lengths and refined site-scattering values of M1 and M4 sites. These changes and the crystal-chemical formula calculated from structure refinement show that all Fe2+ originally at M4 migrates into the ribbon of octahedrally coordinated sites, where most of it oxidises to Fe3+, and there is a corresponding exchange of Mg from the ribbon into M4. The resulting composition is that of an oxo-gedrite with an inferred crystal-chemical formula Na-A(0.47) (B)(Na-0.03 Mg-1.93 Ca-0.04) (C)(Mg-2.56 Mn (0.02) (2+) Fe (0.10) (2+) Fe (1.22) (3+) Al-1.15 Ti (0.05) (4+) ) (T)(Si-6.31 Al-1.69) O-22 (W)[O (1.12) (2-) (OH)(0.88)]. This marked redistribution of Mg and Fe is interpreted as being driven by rapid dehydrogenation at the H3A and H3B sites, such that all available Fe in the structure orders at M1 and M3 sites and is oxidised to Fe3+. Thermoelastic data are reported for gedrite and oxo-gedrite; the latter was measured during cooling from 1,173 to 298 K (Stage 2) and checked after further heating to 1,273 K (Stage 3). The thermoelastic properties of gedrite and oxo-gedrite are compared with each other and those of anthophyllite.

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The crystal chemistry of gedrite-group amphiboles and its relations with their monoclinic BCa counterparts have been only recently clarified.1 This work provides information on the behaviour of gedrite at high-T conditions, in terms of thermal expansivity, cation order and dehydrogenation processes. The only data now available on thermal expansivity of orthorhombic amphiboles concern anthophyllite, ideally AoBMg2CMg5TSi8O22(OH)2,2 where dehydrogenation is prevented by the lack of Fe2+ (in amphiboles, the reaction proceeds via oxidation of Fe2+ at the M1 and M3 sites which are both bonded to the involved O3 oxygen atom). Gedrite sample A(26), with reported composition ANa0.46B(Mg1.11Fe2+0.83Mn0.02Ca0.04) C(Mg3.44 Fe2+0.33 Al1.18Ti0.05)T(Si6.26 Al1.74)O22OH2,1 was annealed up to 1273 K at intervals of 25 K using a micro furnace mounted on the diffractometer. Unit-cell parameters were measured in situ at each step, and structure refinements were done from single-crystal data collected at 533, 723 and 973 K during both annealing and reversal (thus on the partially dehydrogenated phase). Unit-cell parameters increase almost linearly up to 973 K (?V = 3.15 ?10-5 K-1, ?a = 1.10 ?10-5 K-1, ?b = 0.94 ?10-5 K-1, ?c = 1.19 ?10-5 K-1), where an abrupt contraction in all the edges (much stronger in a) indicates the start of the dehydrogenation process. Dehydrogenation proceeds by oxidation of all Fe, which migrates mainly from the M4 to the M1 and M3 sites, thus causing significant changes in site geometry. Reversal experiments down to RT allowed calculation of thermal expansion coefficients of the partially dehydrogenated phase: ?V = 3.51 ?10-5 K-1, ?a = 1.15 ?10-5 K-1, ?b = 1.09 ?10-5 K-1, ?c = 1.26 ?10-5 K-1. The crystal was then heated at 1273 K and finally cooled to room T to check for the completeness (as far as allowed by the Fe2+ content) of the dehydrogenation process. A significant difference in thermal expansivity with respect to anthophyllite is observed only for the much greater stiffness of the a edge (for anthophyllite, ?a = 1.49 ?10-5 K-1)2, and is related to the presence of a half-filled A site in gedrite. In the dehydrogenated sample, Na disorders into two different positions within the A cavity, the second of which is closer to the A double-chain of tetrahedra and particularly closer to the O3A oxygen atom. Hence, the dehydrogenated samples has a different bond valence arrangement. The behaviour of the different cation polyhedra and structure moduli during annealing and dehydrogenation, and differences with respect to anthophyllite and monoclinic amphiboles will be discussed. 1Schindler, M.; Sokolova, E.; Abdu, Y.; Hawthorne, F.C.; Evans, B.E.; and Ishida, K., Mineral. Mag. 2008, 72, 703-730. 2 Cámara, F.; Welch, M.D.; and Oberti, R., IMA2010, Abstracts 2010.

Elevated levels of lipoprotein(a) are associated with a greater risk of atherothrombotic cardiovascular diseases. Since the Lp(a) levels are genetically determined and fairly stable in the course of life and a family history appears to be an independent risk factor of cardiovascular diseases, we evaluated the behavior of Lp(a) levels in patients with early events of coronary heart disease (CHD) and also in subjects with positive family history of ischemic heart diseases.The levels of lipoprotein (a) [Lp(a)] were measured in 254 subjects, 138 males and 116 females with an average age of 48.6 +/- 13.8 years (range 20-76 years). Diabetic subjects, females submitted to oestrogen treatment and those already in treatment with hypolipidaemic drugs were excluded from the study. Forty of the 254 patients (15.7%), 27 males and 13 females, had CHD (29 a previous myocardial infarction and 11 a stable angina). A positive family history for CHD was considered present (102 of the 254 patients) if one or more first degree relatives had angina or myocardial infarction before the age of 60 years in men and 65 in women.The levels of Lp(a) were higher (p0.01) in women (25.1 +/- 28.3 mg/dl) compared to men (17.6 +/- 18.4 mg/dl), without differences in relation to age. The Lp(a) plasmatic levels were not correlated with age, body mass index, total cholesterol, LDL and HDL, triglycerides, apo B, apo AI, fibrinogen and there were no differences in Lp(a) levels in presence or absence of other known cardiovascular risk factors such as hypertension and smoking. The Lp(a) levels were not different between subjects with CHD (28.15 +/- 31.7 mg/dl) and controls (20.3 +/- 22.8 mg/dl). The subjects with CHD were older and had higher levels of fibrinogen and a significantly greater prevalence of hypertension and family history of CHD. Fifteen of the 40 subjects with CHD had an early onset of CHD (before 50 years of age) and only in such patients the Lp(a) levels were significantly greater compared to controls (35.8 +/- 33.2 mg/dl vs 20.3 +/- 22.8 of the controls, p0.01), independently of other variables (age, BMI, smoking, hypertension, cholesterol, triglycerides, HDL-c, LDL-c, fibrinogen). Furthermore the Lp(a) plasmatic levels were higher in subjects with a family history of CHD (28.3 +/- 27.6 mg/dl vs 16.3 +/- 18.6 mg/dl of the subjects without a family history of CHD, p0.01) even if they had or not had a previous coronary ischemic event.Such data confirm the importance of high levels of Lp(a) above all for the early events of CHD and for the subjects with a family history of CHD, which could be expression of a greater predisposition for cardiovascular events.