The freezing of water to ice is fundamentally important fields as diverse cloud formation cryopreservation. At ambient conditions, considered exist in two crystalline forms: stable hexagonal and metastable cubic ice. Using X-ray diffraction data Monte Carlo simulations, we show that crystallizes homogeneously from supercooled neither these phases. resulting disordered one dimension therefore possesses nor symmetry instead composed randomly stacked layers sequences. We refer this...

A new phase of ice, named ice XV, has been identified and its structure determined by neutron diffraction. Ice XV is the hydrogen-ordered counterpart VI thermodynamically stable at temperatures below $\ensuremath{\sim}130\text{ }\text{ }\mathrm{K}$ in 0.8 to 1.5 GPa pressure range. The regions stability medium range diagram have thus finally mapped, with only phases 0 K. ordered antiferroelectric ($P\overline{1}$), clear disagreement recent theoretical calculations predicting ferroelectric...

Traditionally, ice I was considered to exist in two well-defined crystalline forms at ambient pressure: stable hexagonal (ice Ih) and metastable cubic Ic). However, it is becoming increasingly evident that what has been called the past does not have a structure consistent with crystal system. Instead, stacking-disordered material containing sequences interlaced sequences, which termed Isd). In this article, we summarise previous work on stacking disorder including past. We also present new...

Despite relevance to disparate areas such as cloud microphysics and tribology, major gaps in the understanding of structures phase transitions low-dimensional water ice remain. Here, we report a first principles study confined 2D function pressure. We find that at ambient pressure hexagonal pentagonal monolayer are two lowest enthalpy phases identified. Upon mild compression, structure becomes most stable persists up ∼2 GPa, which point square rhombic stable. The agrees with recent...

Amorphous ices govern a range of cosmological processes and are potentially key materials for explaining the anomalies liquid water. A substantial density gap between low-density high-density amorphous ice with water in middle is cornerstone our current understanding However, we show that ball milling "ordinary" I

High-density amorphous ice (HDA), further densified on isobaric heating from 77 K to 165 (177) at 1.1 (1.9) GPa, relaxes and 1 bar the same structural “state” with a density of 1.25 ± 0.01 g cm−3. Its is higher by ≈9% than that HDA, thus it called very-high-density (VHDA). X-ray diffractogram Raman spectrum VHDA clearly differs hydrogen-bonded O–O distance increases 2.82 Å in HDA 2.85 VHDA. Implications for polyamorphism forms water are discussed.

The majority of carboxylic acid groups formed after treatment a single-walled carbon nanotube (SWCNT) material with nitric are present on carboxylated carbonaceous fragments (CCFs) (see figure). These CCFs removed from the SWCNTs by NaOH solution and identified as carriers COOH functionality, implying that previous reports claiming side-wall functionalization should be reconsidered.

Two hydrogen ordered phases of ice were prepared by cooling the disordered ices V and XII under pressure. Previous attempts to unlock geometrical frustration in hydrogen-bonded structures have focused on doping with potassium hydroxide had success partially increasing ordering hexagonal I (ice Ih). By hydrochloric acid, we XIII XIV, analyzed their powder neutron diffraction. The use chloride release opens up possibility completing phase diagram ice.

Our recent discovery of three new phases ice has increased the total number known distinct polymorphs to fifteen. In this Perspective article, we give a brief account previous work in field, and discuss some particularly interesting open questions that have emerged from studies. These include (i) effectiveness acid base dopants enable hydrogen-ordering processes ices, (ii) comparison calorimetric data crystalline low-density amorphous ice, (iii) disagreement between experimental XV structure...

Many acronyms are used in the literature for describing different kinds of amorphous ice, mainly because many preparation routes and sample histories need to be distinguished. We here introduce these ices discuss question how forms relevance context polyamorphism. employ criterion reversible transitions between "states" finite intervals pressure temperature discriminate independent metastable "substates" same "state". argue that experimental evidence suggests we should consider there three...

Water's phase diagram displays enormous complexity with currently 17 experimentally confirmed polymorphs of ice and several more predicted computationally. For almost 120 years, it has been a stomping ground for scientific discovery, research often trailblazer investigations into wide range materials-related phenomena. Here, the experimental progress last couple years is reviewed, open questions as well future challenges are discussed. The specific topics include (i) polytypism stacking...

The search for new nanostructural topologies composed of elemental carbon is driven by technological opportunities as well the need to understand structure and evolution materials formed planetary shock impact events in laboratory syntheses. We describe two families diamond-graphene (diaphite) phases constructed from layered bonded sp3 sp2 units provide a framework classifying members this class materials. nanocomposite structures are identified within both natural diamonds...

The sidewall functionalisation of carbon nanotubes using the standard nitric acid treatment can be greatly enhanced by first removing amorphous present in sample.

Purification and opening of carbon nanotubes has been carried out by treatment as-made single-wall (SWNTs) with pure steam at 1 atm pressure. Treated samples have characterized high-resolution transmission electron microscopy IR Raman spectroscopy. Comparison between the purification standard nitric acid shows that is less aggressive toward damage to tubular nanotube wall structure forms fewer functional groups.

Abstract Elemental phosphorus displays an impressive number of allotropes with highly diverse chemical and physical properties. White has now been filled into single‐wall carbon nanotubes (SWCNTs) from the liquid thereby stabilized against exothermic reaction atmospheric oxygen. The encapsulated tetraphosphorus molecules were visualized transmission electron microscopy, but found to convert readily chain structures inside SWCNT “nanoreactors”. energies possible determined computationally,...

Heterogeneous ice nucleation is an important process in many fields, particularly atmospheric science, but still poorly understood. All known inorganic nucleating particles are relatively large size and tend to be hydrophilic. Hence it not obvious that carbon nanomaterials should nucleate ice. However, this paper we show four different readily water-dispersible capable of The tested materials were carboxylated graphene nanoflakes, oxide, oxidized single walled nanotubes multiwalled...

The glass transitions of low-density amorphous ice (LDA) and high-density (HDA) are the topic controversial discussions. Understanding their exact nature may be key to explaining anomalies liquid water but has also got implications in general context polyamorphism, occurrence multiple forms same material. We first show that transition hydrogen-disordered VI is associated with kinetic unfreezing molecular reorientation dynamics by measuring calorimetric responses corresponding H2O, H218O, D2O...

Abstract Ice is a material of fundamental importance for wide range scientific disciplines including physics, chemistry, and biology, as well space materials science. A well-known feature its phase diagram that high-temperature phases ice with orientational disorder the hydrogen-bonded water molecules undergo transitions to their ordered counterparts upon cooling. Here, we present an example where this trend broken. Instead, hydrochloric-acid-doped VI undergoes alternative type transition...

On compressing low-density amorphous ice (LDA) at 125 K up to 1.6 GPa, two distinct density steps accompanied by heat evolution are observable in pressure-density curves. Samples recovered 77 and 1 bar after the first second show x-ray diffraction pattern of high-density (HDA) very HDA (VHDA), respectively. The compression once formed takes place linearly 0.95 where nonlinear densification --> VHDA conversion is initiated. This implies a stepwise formation process LDA--> K, which best our...

Cumulene sp-carbon molecular wires C2 [Fc(Ph)CC(Ph)Fc] up to C7 [Fc(Ph)CCCCCCC(Ph)Fc] endcapped by two electroactive ferrocenyl groups are presented in this report. Synthetically, cumulenes can be built-up a modular strategy using C1 synthon ferrocenyl(phenyl)ketone as starting material with various acetylenic/propargylic/homopropargylic C2−C5 reagents, taking into account and exploiting the efficient stabilization of an electron-deficient carbenium center adjacent moiety. With increasing...

Ordinary water ice forms under ambient conditions and has two polytypes, hexagonal (Ih) cubic (Ic). From a careful comparison of proton ordering arrangements in Ih Ic using periodic density functional theory (DFT) diffusion Monte Carlo (DMC) approaches, we find that the most stable arrangement molecules is isoenergetic with ordered form (known as XI). We denote this potential new polytype XI XIc discuss possible route for preparing XIc.

Abstract We are all familiar with the hexagonal shape of snow and ice crystals, it is well established that their sixfold symmetry derived from arrangement water molecules in a crystal structure. However, atmospheric crystals only threefold rotational often observed, which inconsistent structure ordinary ice. These found wide range different cloud types ranging upper-tropospheric cirrus to contrails diamond dust they form at temperatures about −84° −5°C. Recent experimental studies...