ISODISPLACE is a new internet-server tool for exploring structural phase transitions. Given parent-phase information, it generates atomic displacement patterns induced by irreducible representations of the parent space-group symmetry and allows user to visualize manipulate amplitude each distortion mode interactively. freely accessible at http://stokes.byu.edu/isodisplace.html via common internet browsers.

A complete table of (3 + 1)D, 2)D and 3)D superspace groups (SSGs) has been enumerated that corrects omissions duplicate entries in previous tables Bravais classes. The theoretical methods employed are not new, though the implementation is both novel robust. paper also describes conventions for assigning a unique one-line symbol each group table. Finally, new online data repository introduced delivers more information about SSG than presented previously.

Abstract Chiral multiferroics offer remarkable capabilities for controlling quantum devices at multiple levels. However, these materials are rare due to the competing requirements of long-range orders and strict symmetry constraints. In this study, we present experimental evidence that coexistence ferroelectric, magnetic orders, crystallographic chirality is achievable in hybrid organic-inorganic perovskites [( R / S )- β -methylphenethylamine] 2 CuCl 4 . By employing Landau mode analysis,...

Charge-lattice fluctuations are observed in the layered perovskite manganite LaSr2Mn2O7 by Raman spectroscopy as high 340 K and with decreasing temperature they become static form a charge ordered (CO) phase below TCO=210 K. In regime, superlattice reflections through neutron x-ray diffraction propagation vector (h+1/4,k-1/4,l). Crystallographic analysis of CO state demonstrates that degree orbital ordering this is weaker than three dimensional manganites. A TN=170K type-A antiferromagnetism...

Time-domain spectroscopy is used to study the complex permittivity of two types liquid crystals: heptylcyanobiphenyl (7CB) and octylcyanobiphenyl (8CB). The variation dominant relaxation frequency values both 7CB 8CB as a function temperature are very similar, showing no influence smectic structure in 8CB. experimental measurements nematic phase agree qualitatively with existing theory.

An algorithm is presented which determines the equivalence of two settings a (3 + d)-dimensional superspace group (d = 1, 2, 3). The has been implemented as web tool findssg on SSG(3+d)D, providing transformation any user-given to standard setting this in SSG(3+d)D. It shown how can be directly obtained by an appropriate external-space lattice vectors (the basic structure unit cell) and internal-space (new modulation wavevectors are linear combinations old plus three-dimensional...

The two commonly used systems of magnetic space-group (MSG) symbols, with accompanying numbers and settings, are those Belov-Neronova-Smirnova (BNS) Opechowski-Guccione (OG). symbols from both have been for several decades now. Both advantages disadvantages. present challenges interpretation to novice expert users alike, which can inhibit understanding lead errors in published structures. To address each these going forward, a new unified (UNI) MSG symbol is introduced, combines modified BNS...

Organic-inorganic metal hybrids with their tailorable lattice dimensionality and intrinsic spin-splitting properties are interesting material platforms for spintronic applications. While the spin decoherence process is extensively studied in lead- tin-based hybrids, these systems generally show short lifetimes, correlation framework still not well-understood. Herein, we synthesized magnetic manganese hybrid single crystals of (4-fluorobenzylamine)2MnCl4, ((R)-3-fluoropyrrolidinium)MnCl3,...

Neutron scattering measurements on a bilayer manganite near optimal doping show that the short-range polaron correlations are completely dynamic at high T, but then freeze upon cooling to temperature T(*) approximately equal 310 K. This glass transition suggests paramagnetic/insulating state arises from an inherent orbital frustration inhibits formation of long-range orbital- and charge-ordered state. Upon further into ferromagnetic-metallic (T(C) = 114 K), where polarons melt, diffuse...

Our simple and uniquely cost-effective solvent-deficient synthetic method produces 3-5 nm Al2O3 nanoparticles which show promise as improved industrial catalyst-supports. While catalytic applications are sensitive to the details of atomic structure, a diffraction analysis alumina is challenging because extreme size/microstrain-related peak broadening similarity patterns various transitional phases. Here, we employ combination X-ray pair-distribution function (PDF) Rietveld methods, together...

Naturally occurring ferrihydrite is both impure and difficult to isolate, so the numerous applications interesting properties of have spurred development various synthetic techniques. Nearly all techniques are based on hydrolysis an iron salt require careful control temperature, pH, concentration. In this Article, we report a new method which does not such perhaps fastest simplest route synthesizing ferrhydrite. XRD, TEM, BET, chemical purity characterizations show that chemically pure,...

The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring solving such structures which will be widely applicable a range functional materials. exemplify the with investigation Bi2Sn2O7 pyrochlore, has been shown undergo transitions from parent γ cubic β α on cooling. results include first reliable model β-Bi2Sn2O7 (orthorhombic Aba2, =...

ISOSUBGROUP , the newest member of ISOTROPY Software Suite (http://iso.byu.edu), generates isotropy subgroups crystallographic space groups based on superpositions multiple irreducible representations, along with a wealth information about each one. Like original program, its scope is general rather than being restricted to common types order parameters user-specified parent structure. But like newer ISODISTORT user-friendly interface has menu-driven selections. This combination features...

Rigid Unit Modes (RUMs), which involve cooperative patterns of polyhedral or molecular rotations and translations, influence a wide variety material properties. Recent work provided an algebraic approach to systematically exhaustively predicting the small-angle RUMs for given crystal structure, are classified by irreducible representations parent symmetry group unrotated structures [1-3]. When some extended large angles, their rigid units become substantially distorted, indicating that they...

New tables of irreducible representations (IRs) are introduced for the 230 crystallographic space groups (SGs) in three-dimensional space, at both special and non-special k vectors, their extensions to (3 + d)-dimensional superspace (`superspace-extended SGs' or SSESGs). Neither a tabulation SG IR matrices vectors nor SSESG d > 1 have been previously published. These tabulations made possible by new form which SGs separated as product translation part T point-operation P, where SSESGs...

The available data on the structural and magnetic transitions in multiferroic hexagonal YMnO3 have been reviewed, first making use of computer programs from group theoretical ISOTROPY software suite to list possible crystal structures, then taking into account capability neutron diffraction other physical methods distinguish them. This leads a clear view transformation sequence, as follows. Hexagonal is paraelectric P63/mmc at elevated temperatures, undergoes single transition cooling...

Crystalline solids consisting of three-dimensional networks interconnected rigid units are ubiquitous amongst functional materials. In many cases, application-critical properties sensitive to rigid-unit rotations at low temperature, high pressure or specific stoichiometry. The shared atoms that connect impose severe constraints on any rotational degrees freedom, which must then be cooperative throughout the entire network. Successful efforts identify cooperative-rotational modes (RUMs) in...

A system of strongly interacting electron-lattice polarons can exhibit charge and orbital order at sufficiently high polaron concentrations. In this study, the structure short-range correlations in layered colossal magnetoresistive perovskite manganite ${\mathrm{La}}_{1.2}{\mathrm{Sr}}_{1.8}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ has been determined by a crystallographic analysis broad satellite maxima observed diffuse x-ray neutron-scattering data. The resulting...

For any crystal structure that can be viewed as a low-symmetry distortion of some higher-symmetry parent structure, one represent the details distorted in terms symmetry-adapted modes rather than traditional list atomic xyz coordinates. Because most symmetry tend to inactive, and only relatively small number mode amplitudes are dominant producing observed distortion, symmetry-mode analysis greatly simplify determination displacively from powder diffraction data. This is an important...

We have recently developed a "solvent-deficient" method of synthesizing high surface area γ-Al2O3 nanoparticles that show promise for catalyst support applications. Here, we investigate doping the alumina with La3+ to stabilize γ phase higher temperatures. The one-pot La-doped here has several advantages over conventional methods including requiring only 3 h instead days and wasting no lanthanum. TEM, X-ray PDF, BET analyses as function calcination temperature La stabilizes by 100 °C. In...

There has been significant recent interest in exploiting the large dimension changes that can occur molecular materials as a function of temperature, stress, or under optical illumination. Here, we report remarkable thermal expansion properties chloranilic acid pyrazine co-crystals. We show compound shows uniaxial negative over wide temperature range with linear contraction coefficient low (−)1500 × 10–6 K–1 at 250 K. The corresponding 10% between 200 and 300 K is an order magnitude larger...

Abstract A comprehensive x‐ray scattering study of spontaneous magnetostriction in hexagonal MnTe, an antiferromagnetic semiconductor with a Néel temperature T N = 307 K, is presented. The largest magnetovolume effect known for antiferromagnet observed, reaching volume contraction |Δ V / | > 7 × 10 −3 . This can be justified semiquantitatively by considering bulk material properties, the spatial dependence superexchange interaction, and geometrical arrangement magnetic moments MnTe....