Octahedral Voids Research Articles

Polymorphism of Ag3VO4

The polymorphism of Ag3VO4 was investigated with temperature dependent synchrotron powder diffraction, and differential scanning calorimetry in the temperature range 295 K ≤ T ≤ 893 K. Three crystal structures of Ag3VO4 were identified and determined from powder diffraction data: α-Ag3VO4 (T = 295 K, C2/c, a = 10.2672(2) Å, b = 4.9814(1) Å, c = 10.2240(2) Å, β = 116.0(1)°, V = 470.0(2) Å3), β-Ag3VO4 (T = 423 K, I-42m, a = 4.9968(1) Å, c = 9.6911(3) Å, V = 241.97(1) Å3), and γ-Ag3VO4 (T = 703 K, Fm-3m, a = 7.8386(1) Å, V = 481.62(1) Å3). The crystal structures of all three phases of Ag3VO4 can be described as cubic closed packed arrangements of [VO4]3– anions with the silver cations occupying all octahedral and tetrahedral voids.

RE2+xI2M2+y (RE = Ce,Gd, Y; M = Al, Ga): Reduced Rare Earth Halides with a Hexagonal Metal Atom Network

Abstract The title compounds were synthesized from RE, REI3 (RE = Ce, Gd, Y) and Al or Ga under an Ar atmosphere at 930 - 950 °C. The non-stoichiometric Ce2+xI2Al2+y and Ce2+xI2Ga2+y compounds crystallize in the space group R3̄m (No. 166) with lattice constants a = 4.3645(3), c = 35.914(2) Å for the Al and a = 4.3009(2), c = 35.680(4) Å for the Ga compound. Excess electron density found in the Wyckoff position 3a could be due to a fractional occupation by Ce or M (x = 0.06, y = 0 or x = 0, y = 0.11 in the case of the Ga compound). The stoichiometric Gd2I2Ga2 and Y2I2Ga2 compounds crystallize in the space group P3̄m1 (No. 164) with lattice constants a = 4.1964(1) and 4.1786(7) Å , c = 11.4753(4) and 11.434(2) Å , respectively. Their structures feature M-centered (M = Al, Ga) RE trigonal prisms condensed via common rectangular faces. The electronic origin of the surplus of metal atoms in the octahedral voids between the I-layers of the Ce compounds was explored via extended Hückel-type calculations. Magnetic susceptibility, electrical resistivity and heat capacity measurements have also been carried out. These reveal a metal-insulator transition of Gd2I2Ga2 at 40 K.

Insights into the Structure and Dynamics of a Room-Temperature Ionic Liquid: Ab Initio Molecular Dynamics Simulation Studies of 1-n-Butyl-3-methylimidazolium Hexafluorophosphate ([bmim][PF6]) and the [bmim][PF6]−CO2 Mixture

Ab initio molecular dynamics (AIMD) studies have been carried out on liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and its mixture with CO2 using the Car-Parrinello molecular dynamics (CPMD) method. Results from AIMD and empirical potential molecular dynamics (MD) have been compared and were found to differ in some respects. With a strong resemblance to the crystal, the AIMD simulated neat liquid exhibits many cation-anion hydrogen bonds, a feature that is almost absent in the MD results. The anions were observed to be strongly polarized in the condensed phase. The addition of CO2 increased the probability of this hydrogen bond formation. CO2 molecules in the vicinity of the ions of [bmim][PF6] exhibit larger deviations from linearity in their instantaneous configurations. The polar environment of the liquid induces a dipole moment in CO2, lifting the degeneracy of its bending mode. The calculated splitting in the vibrational mode compares well with infrared spectroscopic data. The solvation of CO2 in [bmim][PF6] is primarily facilitated by the anion, as seen from the radial and spatial distribution functions. CO2 molecules were found to be aligned tangential to the PF6 spheres with their most probable location being the octahedral voids of the anion. The structural data obtained from AIMD simulations can serve as a benchmark to refine interaction potentials for this important room-temperature ionic liquid.

Synthesis, Crystal Structure, and Properties of Two Modifications of MgB12C2

Single crystals of two modifications of the new magnesium boride carbide MgB(12)C(2) were synthesized from the elements in a metallic melt by using tantalum ampoules. Crystals were characterized by single-crystal X-ray diffraction and electron microprobe analysis (energy-dispersive (EDX) and wavelength-dispersive (WDX) X-ray spectroscopy). Orthorhombic MgB(12)C(2) is formed in a Cu/Mg melt at 1873 K. The crystal structure of o-MgB(12)C(2) (Imma, Z=4, a=5.6133(10), b=9.828(2), c=7.9329(15) A, 574 reflections, 42 variables, R(1)(F)=0.0208, wR(2)(I)=0.0540) consists of a hexagonal primitive array of B(12) icosahedra with Mg atoms and C(2) units in trigonal-prismatic voids. Each icosahedron has six exohedral B--B and six B--C bonds. Carbon is tetrahedrally coordinated by three boron atoms and one carbon atom with a remarkably long C--C distance of 1.727 A. Monoclinic MgB(12)C(2) is formed in an Al/Mg melt at 1573 K. The structure of m-MgB(12)C(2) (C2/c, Z=4, a=7.2736(11), b=8.7768(13), c=7.2817(11) A, beta=105.33(3) degrees , 1585 reflections, 71 variables, R(1)(F)=0.0228, wR(2)(I)=0.0610) may be described as a distorted cubic close arrangement of B(12) icosahedra. Tetrahedral voids are filled by C atoms and octahedral voids are occupied by Mg atoms. The icosahedra are interconnected by four exohedral B--B bonds to linear chains and by eight interstitial C atoms to form a three-dimensional covalent network. Both compounds fulfill the electron-counting rules of Wade and Longuet-Higgins.

A Single-Source Solid-Precursor Method for Making Eco-Friendly Doped Semiconductor Nanoparticles Emitting Multi-Color Luminescence

A novel synthesis method is presented for the preparation of eco-friendly, doped semiconductor nanocrystals encapsulated within oxide-shells, both formed sequentially from a single-source solid-precursor. Highly luminescent ZnS nanoparticles, in situ doped with Cu(+)-Al3+ pairs and encapsulated with ZnO shells are prepared by the thermal decomposition of a solid-precursor compound, zinc sulfato-thiourea-oxyhydroxide, showing layered crystal structure. The precursor compound is prepared by an aqueous wet-chemical reaction involving necessary chemical reagents required for the precipitation, doping and inorganic surface capping of the nanoparticles. The elemental analysis (C, H, N, S, O, Zn), quantitative estimation of different chemical groups (SO4(2-) and NH4(-)) and infrared studies suggested that the precursor compound is formed by the intercalation of thiourea, and/or its derivatives thiocarbamate (CSNH2(-)), dithiocarbamate (CS2NH2(-)), etc., and ammonia into the gallery space of zinc-sulfato-oxyhydroxide corbel where the Zn(II) ions are both in the octahedral as well as tetrahedral coordination in the ratio 3 : 2 and the dopant ions are incorporated within octahedral voids. The powder X-ray diffraction of precursor compound shows high intensity basal reflection corresponding to the large lattice-plane spacing of d = 11.23 angstroms and the Rietveld analysis suggested orthorhombic structure with a = 9.71 angstroms, b = 12.48 angstroms, c = 26.43 angstroms, and beta = 90 degrees. Transmission electron microscopy studies show the presence of micrometer sized acicular monocrystallites with prismatic platy morphology. Controlled thermolysis of the solid-precursor at 70-110 degrees C leads to the collapse of layered structure due to the hydrolysis of interlayer thiourea molecules or its derivatives and the S2- ions liberated thereby reacts with the tetrahedral Zn(II) atoms leading to the precipitation of ZnS nanoparticles at the gallery space. During this process, the dopant ions situated at octahedral voids gets incorporated into the nano-ZnS lattice and results in bright photoluminescence. On further heat treatment above 1100 degrees C, the corbel zinc-oxyhydroxide sheets undergo dehydroxylation to form ZnO which eventually encapsulates the ZnS nanoparticles at the gallery leading to significant enhancement in the luminescence quantum efficiency, up to approximately 22%. The emission color of thus formed nano-ZnS/micro-ZnO composites could be tuned over wide spectral ranges from 480 to 618 nm and the spectral changes are attributed to a number of factors including lattice defects, Cu(+)-Al3+ dopant-pairs and iso-electronic oxygen in nano-ZnS and oxygen-vacancy or -interstitial centers in non-stoichiometric ZnO.

Polymerization of the rotor-stator compoundC60-cubane under pressure

Cubane, C8H8, can be inserted into the octahedral voids of fullerene lattices to create a family of rotor-stator compounds. We have investigated the structural phase behavior of C60 center dot C8H8 ...

Structural study of C60 and C70 cubane

AbstractFullerenes and cubane (C8H8) form new high‐symmetry heteromolecular crystals and C60–cubane and C70–cubane are the first members of this family. We present the results of a detailed structural study in a wide temperature range, from 100 K to 470 K. The structure of these compounds is based on the well‐known face centered cubic (fcc) C60 lattice. In the highest symmetry case freely rotating fullerenes occupy the fcc lattice sites, and cubanes fill the octahedral voids. We found various phase transitions on lowering the temperature. As expected, the free rotation of fullerenes becomes hindered and orientational ordering appears. The orientational transition temperature is exceptionally low, which can be explained by the combination of the high symmetry environment of fullerenes, the perfect match of convex fullerene and concave cubane molecular surfaces and the significantly expanded fullerene lattice. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The metal-rich palladium chalcogenides Pd 2MCh2 ( M=Fe, Co, Ni; Ch=Se, Te): Crystal structure and topology of the electron density

Crystals of Pd 2 MCh 2 ( M=Fe, Co, Ni; Ch=Se, Te) were synthesized by heating the elements at 823–1323 K in silica ampoules under argon atmosphere. Their structures were determined by single-crystal X-ray diffraction at room temperature. The metallic compounds crystallize in a variant of the K 2ZnO 2 type ( Ibam, Z=4, Pd 2CoSe 2: a=5.993(1), b=10.493(2), c=5.003(1) Å; Pd 2FeSe 2: a=5.960(1), b=10.576(2), c=5.078(1) Å; Pd 2CoTe 2: a=6.305(1), b=11.100(2), c=5.234(1) Å; Pd 2NiTe 2: a=6.286(1), b=11.194(2), c=5.157(1) Å). One-dimensional ∞ 1 [ MC h 4 / 2 ] tetrahedra chains with remarkably short M— M bonds run along [001], separated by [Pd 2] dumbbells with palladium in fivefold coordination of selenium or tellurium atoms. The structure may also be described as a filled variant of the SiS 2 type. M atoms occupy 1 4 of the tetrahedral voids and the Pd atoms fill all octahedral voids in a distorted ccp motif of chalcogen atoms. Even though the Pd 2 MCh 2 compounds are isotypic to K 2ZnO 2 from the crystallographic viewpoint, we find a different bonding situation with additional homo- and heteronuclear metal–metal bonds between the Pd and Co atoms. The electronic structures and topologies of the electron densities of Pd 2CoSe 2 and isotypic Na 2CoSe 2 are analyzed and compared by using Bader's AIM theory. Different values of topological charge transfer and electron density flatness indices uncover striking quantitative differences in the nature of chemical bonding between the metallic compound Pd 2CoSe 2 and nonmetallic Na 2CoSe 2.

Low-dimensional sublattice melting by pressure: Superionic conduction in the phase interfaces of the fluorite-to-cotunnite transition ofCaF2

The pressure-induced phase transformation of calcium fluoride ! CaF2 from the cubic-fluorite-type structure ! Fm3 m to the orthorhombic cotunnite ! PbCl2 type structure ! Pnma is investigated from transition path sampling molecular dynamics simulations. Starting from an artificially prepared transformation route connecting fluorite to cotunnite, subsequent trajectory rectification evolved to a distinct picture of the favored mechanism. The latter is characterized by nucleation and growth of the new phase. The overall transformation mechanism was identified as a symmetry-lowering step from the cubic to the orthorhombic atomic configuration which is caused by the reorganization of one half of the octahedral voids. At the interface between the cubic and the orthorhombic structure, a pressure-induced local melting of the fluoride sublattice is observed. This produces defects that allow for the reorganization of the calcium sublattice which eventually leads to the recrystallization of the fluoride ions fixating one of the stable structures. Variation of the thermodynamic parameters shows that the mechanism is conserved over the experimentally relevant range, however with an increasing tendency towards incomplete transformation on lowering the temperature, in accordance with experiments.

TlBiS2

The ternary compound thallium bismuth disulfide crystallizes in the space group R\overline{3}m and is isotypic with the structures of most of the ABQ 2 chalcogenides (A = monovalent atom, B = trivalent atom and Q = chalcogen), which are members of the α-NaFeO2 structure type. In the title compound, the Tl and Bi atoms are situated on positions with \overline{3}m symmetry, whereas the S atom sites exhibit 3m symmetry. The metal atoms occupy octahedral voids in distinct planes perpendicular to the c axis. The environment around Tl is more distorted than the polyhedron around Bi.

Die Aluminidiodide La24Al12I21 und La10Al5I8: Verbindungen mit intermetallischen La‐Al‐Bereichen und La‐Al‐Clustern

AbstractThe Aluminide Iodides La24Al12I21 and La10Al5I8: Compounds with Intermetallic La‐Al Fractions and La‐Al ClustersReacting pieces of La, LaI3 and Al filings (molar ratio 22 : 8 : 15) at 800 °C–825 °C results in La24Al12I21 (70 % yield) together with La10Al5I8 (10 % yield), besides known La3Al2I2 and La2Al2I. Both new compounds form golden coloured needles. La10Al5I8 is brittle, whereas La24Al12I21 is shaped as hair‐like easily deformable bundles. Both are monoclinic, space group C2/m, La24Al12I21 with a = 35.753(7) Å, b = 4.327(1) Å, c = 27.442(6) Å, β = 116.62(3)° and La10Al5I8 with a = 19.649(1) Å, b = 4.296(1) Å, c = 18.0290(1) Å and β = 96.67(3)°. The La atoms form trigonal prisms condensed into double chains along [010]. The La prisms are centered by Al atoms which form Al6 rings connected into chains. The La‐Al strands are surrounded by I atoms in La24Al12I21, whereas in La10Al5I8 they are connected to form corrugated sheets separated by close packed layers of I atoms together with Al atoms. The octahedral voids around the Al atoms are occupied by La atoms, and such La6Al clusters are connected via opposite edges to octahedra chains along [010].

The Stannides AuNiSn2 and AuCuSn2 – Bulk Synthesis and Superstructure Determination

AbstractThe stannides AuNiSn2 and AuCuSn2 were prepared by melting of the elements in silica ampoules at 1300 K followed by slow cooling to room temperature. The structures of both compounds were refined on the basis of single crystal X‐ray data: $P{\bar 3}m{\rm 1}$, a = 412.41(14), c = 529.24(11) pm, wR2 = 0.0268, 159 F2 values, 10 variables for AuNiSn2 and a = 425.97(17), c = 526.88(15) pm, wR2 = 0.0507, 159 F2 values, 11 variables for AuCuSn2 (twinned crystal, BASF = 0.305(4)). These stannides crystallize with a superstructure of the NiAs type with a complete ordering of the transition metal atoms. They derive from a AuSn subcell structure, where every other layer of octahedral voids in the hexagonal closest packing of the tin atoms is filled by nickel in AuNiSn2 and by copper in AuCuSn2. Due to the symmetry reduction smaller NiSn6/6 (CuSn6/6) and larger AuSn6/6 octahedra alternate along the c axis. The crystal chemistry is discussed on the basis of a group‐subgroup scheme.

Nuclear magnetic resonance structural investigations of ammonia-doped fullerides

The dynamic and structural properties of the ammonia-doped superconducting fulleride (NH3)xNaK2C60 (0.5< or =x< or =1), well known for its anomalous decrease of transition temperature with doping, have been investigated using sodium and deuterium solid-state NMR techniques. The independence of 23Na quadrupole splitting from the ammonia content x, which, at the same time, substantially affects Tc, suggests a marginal role of the cation position in the superconducting mechanism. On the other hand, a strong reduction of the deuterium quadrupole coupling with respect to the free ammonia value denotes the presence of weak hydrogen bonds between the deuterium atoms and fullerene pi orbitals. Despite the bond weakness, as evinced by the lively ammonia rotational dynamics even at very low temperatures, the resulting electron localization could explain the observed Tc anomaly. The motion of the ND3-Na group (located in the compound's octahedral voids), as well as the evolution of the ammonia dynamics as a function of temperature, were determined from deuterium NMR line shape analysis and from detailed numerical simulations. While at the lowest measured temperatures only the ammonia rotation around its own C3 axis takes place, above approximately 25 and 70 K, respectively, also the wobbling of the C3 axis and the ND3 relocation become active, successfully modeled by a strongly correlated motion involving two different time scales.

Crystal chemistry and spectroscopic properties of ScAuSn, YAuSn, and LuAuSn

The stannides ScAuSn, YAuSn, and LuAuSn were synthesized as single phase materials from the elements via arc-melting. All samples were characterized by X-ray diffraction on powders and single crystals: MgAgAs type, F 4 ¯ 3 m , a = 641.94 ( 12 ) pm , w R 2 = 0.035 , 85 F 2 values, 5 variables for ScAuSn, a = 656.52 ( 8 ) pm , w R 2 = 0.029 , 89 F 2 values, 5 variables for LuAuSn, and NdPtSb type, P 6 3 m c , a = 463.55 ( 16 ) , c = 737.26 ( 15 ) pm , w R 2 = 0.057 , 233 F 2 values, 11 variables for YAuSn. The gold and tin atoms in ScAuSn and LuAuSn build up three-dimensional [AuSn] networks of corner-sharing AuSn 4/4 tetrahedra (278 and 284 pm Au Sn in ScAuSn and LuAuSn, respectively) similar to the blende type structure. The scandium atoms fill octahedral voids formed by the tin substructure. In contrast, the [AuSn] network of YAuSn is two-dimensional. The gold and tin atoms build up layers of puckered [Au 3Sn 3] hexagons with intralayer Au Sn distances of 277 pm, while the interlayer Au Sn distances of 297 pm are much longer. In every other layer the [Au 3Sn 3] hexagons are rotated by 60°. The layers are separated by the yttrium atoms. Spectroscopic measurements indicate significant differences in the chemical bonding properties: As revealed by both 119Sn Mössbauer spectroscopy and 119Sn solid-state NMR data, the local electronic environment at the tin site is more anisotropic in YAuSn as compared to the other materials, which feature tin on a site with cubic point symmetry. In ScAuSn, the cubic site symmetry of the scandium position is reflected by a single sharp line in the 45Sc solid-state NMR spectrum.

Diffusion of He atoms in fullerite [formula omitted

In situ X-ray powder diffraction has been utilized to study the He diffusion kinetics in C 60 by monitoring the time dependence of the structure characteristics (lattice parameter, reflection intensities and widths). Based on the time variations of the structure characteristics the intercalation is shown to occur in two stages: octahedral voids are filled during the faster stage 1, while during the much slower stage 2 tetrahedral voids are filled. To make experimental intensities consistent with the estimates made, we came to the conclusion that during the first third of stage 1 at least part of octahedral voids accommodate two helium atoms rather than one. The room-temperature diffusion coefficient (about 7 × 10 - 14 cm 2 / s ) of He over octahedral voids of C 60 has been evaluated from the time dependence of the lattice parameter. Analysis of the degassing kinetics gives diffusion coefficients very close to those obtained from intercalation measurements. The characteristic time constant of the tetrahedral filling is an order of magnitude longer than for octahedral filling, which indicates that the respective effective diffusivity is four orders of magnitude slower compared to infusion into octahedral voids. Thermodynamics of intercalation of He into C 60 at room temperature has been constructed to show that the entropy factor is the main thermodynamic force in the case discussed. These consideration leads also to the conclusion that the internal pressure due to the kinetic energy of He atoms in octahedral voids is large enough to expand the C 60 lattice to the extent observed in experiment.

Characterization of Crystal-Originated Particles in Silicon Nitride Doped, CZ-Grown Silicon Wafers

Grown-in crystal-originated particles (COPs) on the surface of silicon nitride-doped Czochralski (CZ)-grown silicon wafers were characterized using atomic force microscopy and scanning electron microscopy. These nanometer-scale COPs are categorized into kite-shaped, parallelepiped-plate and needle-shaped COPs, respectively, with unique features distinctively different from the octahedral voids commonly found in conventional CZ-grown silicon wafers. Based on the experimental data obtained, it is postulated that nitrogen dopants in the silicon crystals could influence the formation of these COPs with different morphologies and sizes. This may be supported by a simple analysis of the mapping distribution of COPs on the nitride-doped CZ-grown silicon wafer, which reveals that the densities of the smaller-size parallelepiped-plate and needle-shaped COPs are negligible at the center of the silicon wafer but increase to a significant proportion comparable to that of the kite-shaped COPs at the outer edges of the silicon wafer along the radial directions. These observations are thought to correlate well with the presence of nitrogen dopants and the radial concentrations of the excess free vacancy.

Structural behaviour of β-Cu 2− δSe ( δ = 0, 0.15, 0.25) in dependence on temperature studied by synchrotron powder diffraction

Superionic β-copper selenide, β-Cu 2− δ Se ( δ = 0, 0.15, 0.25), has been studied by synchrotron powder diffraction and calorimetric methods in the range 293 K < T < 823 K. Cu 1.75Se exists in the superionic phase at room temperature and remains stable in air up to 600 K. Cu 1.85Se exists at room temperature as a mixture of β and α phases, β + α → β phase transition is not detected in DCS experiment, however, pure β-phase was observed in diffraction pattern of Cu 1.85Se at 353 K; Cu 1.85Se remains stable in air up to 600 K. A copper release process starts in Cu 2Se at a temperature below the superionic–non-superionic phase transition. At T > 543 K the composition is close to Cu 1.95Se and remains stable up to 573 K. Time average structure of β-Cu 2− δ Se has been analysed in the whole temperature range of existence in air. A face centred cubic unit cell (space group F m 3 ¯ m ) is formed by the selenium anions with copper cations distributed over tetrahedral 8(c) and 32(f) ( x, x, x) split positions within the octahedral voids (1/3 < x < 1/2). The copper occupancy of the 32(f) sites increases with temperature with a simultaneous decrease in the 8(c) sites. Besides, the copper occupancy of the 32(f) lattice site also increases with the total copper content 2 − δ. A diffusion pathway of mobile Cu ions along the tetrahedral sites, in “skewed” 〈1 0 0〉 directions through the peripheries of octahedral cavities is proposed.

High-Pressure Studies of the Rotor-Stator Compound C60-Cubane

AbstractInsertion of cubane (C8H8) into the octahedral voids of the C60 lattice leads to the formation of an interesting rotor-stator compound which can be converted into a C60 co-polymer by heating. We have treated a number of C60·C8H8 samples for up to 3 h each in the range 380-875 K under pressures up to 2 GPa. The resulting materials were investigated by Raman spectroscopy and X-ray diffraction. Depending on treatment conditions, at least five different structural phases can be found. In addition to the four structural phases observed at atmospheric pressure and different temperatures we find that a new polymeric state is created at pressures above 1 GPa, and we tentatively identify its structure as pseudo-orthorhombic. The cubic-orthorhombic phase transition line is found to have a slope of 295 K GPa-1, much larger than the slope of the fcc-sc line in pure C60.

Ce29Al14I28: Ein Komposit aus intermetallischer Phase und Metallclustern

AbstractCe29Al14I28: A Composite of Intermetallic Phase and Metal ClustersSingle crystals of Ce29Al14I28 form at 900 °C from CeI3, Ce and Al. The compound crystallises in C2/m with a = 19.471(3), b = 4.308(1), c = 19.526(3) Å und β = 102.75(2)°. Pronounced diffuse scattering occurs and is discussed in terms of special disordered arrangements of discrete building units. The structure of Ce29Al14I28 is composed of two characteristic substructures. One part of the Ce atoms forms pairs of face‐linked trigonal prisms which are connected into layers via edges. Al atoms in the prism centers are arranged in ribbons of planar Al6 rings as in the structure of Ce3Al2I2. Between these ordered layers another kind of layers of close‐packed I atoms occur whose octahedral voids are partially occupied by Ce atoms. Some of the I‐atoms are substituted by Al which are completely surrounded by Ce atoms resulting in octahedral Ce6Al clusters. Most of these clusters are connected into Ce10Al2 units via edge‐sharing, and such units are rather ordered within one layer, however, with no long range order and no correlation with adjacent layers. The prism layers represent sections of an intermetallic phase which are separated by non‐metallic cluster structures.

Structure change of Mn2O3 under high pressure and pressure-induced transition

Abstract Bixbyite (Mn,Fe)2O3 has a C-type rare-earth oxide structure with space group of Ia-3 and different from corundum structure R-3c. Single-crystal structure analyses and powder diffraction experiments were carried out using synchrotron radiation under high pressures up to 41.21 GPa. Lattice constants and bond distances were elucidated as a function of pressure. Single crystal structure analyses under high pressures up to 9.64 GPa have been executed using DAC. There are two octahedral Mn3+ sites: M1 (-3) and M2 (-2.). M1O6 and M2O6 octahedral volumes and void space of vacant sites show different compression curves. M1O6 octahedron is less compressive than M2O6 octahedron. The former is a little deformed from an ideal octahedron with m-3m of MnO6 but the latter is a largely distorted octahedron. The quadratic elongation is applied in order to comprehend the polyhedral distortion and finite homogeneous strain. Both octahedra do not show a noticeable Jahn-Teller distortion induced from Mn3+. Six bond lengths of M1O6 are equivalent but the octahedron more elongates along the direction of -3 axis with increasing pressure and is more deformed from the regular octahedron. The M2O6 octahedron has two long bond distances among six bonds, which are most compressive. The octahedral deformations seem to reduce the Jahn-Teller effect due to the compression. The bulk modulus: Ko = 169.1(4.9) GPa and Ko′ = 7.35(0.99), was observed from the volume change with pressure. Pressure-induced phase transition was confirmed at about 21 GPa with a large hysteresis. The transition is reversible and non-quenchable. Powder indexing of the high-pressure phase was carried out using diffraction pattern taken at 35.06 GPa. It has a monoclinic symmetry and is not a corundum, Rh2O3(II) or perovskite structure.