Deeper understanding of the basic principles of biomineralization is a major challenge for present and future research. The high complexity of in‐vivo conditions calls for simplified model systems that still involve dynamic processes like reorganization, formation, self‐organization, and development of patterns, respectively. The present contribution deals with hierarchically ordered spherical aggregates of fluorapatite–gelatin composites with fractal architecture that are grown in gelatin matrices. The model system was chosen to mimic formation conditions on a lower level of complexity compared with the natural formation of calcified tissue (bone, teeth). In order to gain insight into structure formation and the motif for this special kind of morphogenesis we investigated the interaction of the organic and inorganic components of aggregates in different growth stages by detailed chemical analyses, thermoanalytical measurements, X‐ray diffraction on solitary particles, and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) investigations. The close relation of the results and observations to calcified tissue may stimulate advanced interests in the fields of medical and materials development.

Biominerals are impressive composite materials because of their complex organization and perfect adaptation to the demands of living organisms. Structure and development of human teeth are compared to similar composite systems that develop in vitro under biomimetic conditions without the controlling influence of cells.

Form follows the ion: The morphogenesis of fluorapatite–gelatine nanocomposites is studied from both electron microscopy and atomistic simulation revealing ion impregnation effects on the growth mechanisms. Depending on the ionic species used for pre‐treatment of the organic component dramatic changes of the mesoscopic structuring are observed.

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Besides temperature at one atmosphere, the applied pressure is another important parameter for influencing and controlling reaction pathways and final reaction products. This is relevant not only for the genesis of natural minerals, but also for synthetic chemical products and technological materials. The present critical review (316 references) highlights recent developments that utilise high pressures and high-temperatures for the synthesis of new materials with unique properties, such as high hardness, or interesting magnetic or optoelectronic features. Novel metal nitrides, oxonitrides as well as the new class of nitride-diazenide compounds, all formed under high-pressure conditions, are highlighted. Pure oxides and carbides are not considered here. Moreover, syntheses under high-pressure conditions require special equipment and preparation techniques, completely different from those used for conventional synthetic approaches at ambient pressure. Therefore, we also summarize the high-pressure techniques used for the synthesis of new materials on a laboratory scale. In particular, our attention is focused on reactive gas pressure devices with pressures between 1.2 and 600 MPa, multi-anvil apparatus at P < 25 GPa and the diamond anvil cell, which allows work at pressures of 100 GPa and higher. For example, some of these techniques have been successfully upgraded to an industrial scale for the synthesis of diamond and cubic boron nitride.

The seeder of the pack: The electrical potential distribution (see phase image of an electron hologram) around the basal plane close to the prism faces of a hexagonal fluorapatite–gelatine nanocomposite seed influences the growth of the nanocomposite. The seed consists of elementary dipoles on the nanometer scale, which all have the same orientation along the c axis of the composite seed. Further form development of the seed leads to fractal patterns.

The ability to prepare nanostructured and/or nanocomposite materials on a large scale by simple and controllable routes still remains a challenge in chemistry and material science. By employing well-established synthetic strategies, nanoparticles with different sizes, shapes and compositions can be readily produced. The high tendency for self-aggregation and selforganization of these nanosized building blocks, which are surface-stabilized by organic molecules, into superstructures has been used to create 2D and 3D assemblies. [1][2][3][4][5][6][7][8][9] In the last decade, a series of 3D colloidal superlattices composed of different nanoparticles (Ag, Au, PbS, PbSe, CeO 2 , FePt, CoPt 3 , Fe 3 O 4 , PbSe/Au, Fe 2 O 3 /PbSe, PbSe/Pd, CdSe/PbSe, etc.) has been reported. [10][11][12][13][14][15][16][17][18][19][20] Particularly, PbS-organic nanoparticles of different shapes (including cubes, octahedra, truncated octahedra, rhombicuboctahedra, etc.) can be easily synthesized on a large scale, and attracted much attention [15,16,21,22] because of a variety of possible applications. [23][24][25][26][27] Therefore, this kind of system provides a chance to study diverse packing arrangements (e.g., fcc, bcc, etc.) and specific orientational ordering of nanoparticles. [11,13,15,16,28,29] Experimental observations [16,[29][30][31][32][33][34] suggest that nanoparticles within a colloidal crystal tend to arrange in such a way that the optimal packing efficiency is achieved (principle of maximum space filling [35] ). In a relatively common case of truncated octahedrally shaped nanoparticles, the available experimental data [4,5,16,[29][30][31][32][33]36] allow to rationalize the formation of a particular type of the superlattice array (depending on the degree of coverage of nanocrystals by organic molecules) by considering four phenomenological models: A) Rigid, anisotropically shaped space-filling nanoparticles (inorganic part) without or with a tiny shell of organic molecules; B) Hard spheres with a comparatively large anisotropic core (inorganic part) covered by a relatively thin shell of organic molecules; C) Hard spheres with a comparatively small anisotropic core (inorganic part) and a thick shell of organic molecules; D) Soft and easily deformable spheres with a small anisotropic core (inorganic part) and an even thicker shell of organic molecules.For each case (A-D) the type of superlattice packing (translational order [37] ) and orientational ordering of nanoparticles within the superlattice array is significantly different. In the simplest case (A), the more or less pure, inorganic, truncated octahedrally shaped nanoparticles assemble into a bcc superlattice [33] with 100 % packing efficiency and strong orientational relationship (crystallographic directions of nanocrystals are coaxial with those of the superlattice). [35,37] In case of models B and C, by increasing the degree of coverage of anisotropic (inorganic) nanoparticles by organic molecules, their faces are continuously smoothed, thereby introducing a certa...

Stoichiometric barium pernitride, BaN(2), was prepared from the elements under N(2) pressure of 5600 bar in an autoclave at 920 K. The compound is isotypic to ThC(2) (space group C2/c, Z = 4) according to powder X-ray (neutron) diffraction data with a = 7.1712(1), b = 4.3946(1), c = 7.2362(1) A, and beta = 104.864(1) degrees (a = 7.1745(1), b = 4.3963(1), c = 7.2393(1) A, beta = 104.876(1) degrees ). The N-N distance of 1.221(4) A (based on the neutron diffraction data) is indicative of a double bond in the N(2)(2-) dumbbells. BaN(2) is metallic according to magnetic susceptibility measurements and TB-LMTO band structure calculations.