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In case of reactions, it is a necessary condition that the free energy of formation, Δ f G, of the product is lower than the total free energies of formation of the reactants. The free energy of all reactions and/or all compounds have not been determined in the literature. In this paper, we report the formation, stability, and reactions for all compounds based on their free energies. However, it also seems possible to discuss them based on their lattice energies, because it can be calculated for many compounds if their composition, structure and their lattice parameters are known. Also, we can discuss the formation, stability, etc., for compounds excluding small effects due to temperature and entropy. As a result of the calculations, the lattice energy correlates with the perovskite distortion.

Neutron powder diffraction was used to investigate the detailed structure of the novel nanoporous oxide 12CaO·7Al 2 O 3 (C12A7) over a wide temperature range. The position of the free oxygen ion captured in the cage structure of C12A7 was confirmed to be displaced from the center of the cage as well as from the S 4 axis running through the two calcium ions at the top and the bottom of the cage. The calcium ions were also found to move off of the S 4 axis and shift toward the center of the cage when the free oxygen ion is present inside the cage. Examination of the structure revealed three types of aluminum–oxygen bonds which are characterized as short, medium and long. The distance between the free oxygen ion and the oxygen ion forming the longest bond with an aluminum ion becomes shorter as the temperature increases, suggesting promotion of exchange of the oxygen ions between the two sites. A possible migration path of the oxygen ion is examined from the obtained structural configuration.

We have developed a direct patterning method to form Cu 2 O patterns onto substrates by an electrodeposition method with a glass capillary tube, including an electrolyte containing CuSO 4 and chelating agent. Cu 2 O pattern on the titanium substrates was successfully fabricated at 60 °C. Furthermore, we found that the chelating agent, which has −CH(OH)COOH group, was effective to form crystalline Cu 2 O patterns.

A mild hydrothermal method has been developed to synthesize spinel-type lithium manganese oxide nanocrystallites directly from commercial LiOH, Mn(NO3)2 and H2O2 at 90–110 °C for 8 h. The as-prepared products were characterized by X-ray diffraction (XRD), inductively coupled plasma–atomic emission spectroscopy and chemical analysis. The analysis results indicated that spinel-type lithium manganese oxides with the compositions of Li1+xMn2−xO4−δ (0.09≤x≤0.28, δ

Raman and X-ray diffraction spectroscopy of nonstoichiometric phases in the yttria-rich side of the Y2O3–ZrO2 binary oxide system is presented. Samples with Y2O3 content from 10 to 100 mol.% were prepared by melting powder mixtures in air using an arc-image furnace. The main peak in the X-ray diffraction spectra corresponds to the reflection (111) of the zirconia–yttria cubic solid solution and showed a continuous shifting with increasing zirconia content and also broadening in a wide compositional region. The widest broadening was found at around 30 mol.% Y2O3. The observed features can be attributed to the superposition of different but close peaks corresponding to several solid solutions with different symmetry. However, a reliable analysis of the presence of different cubic phases cannot be performed by conventional X-ray spectroscopy. To my knowledge, the evolution of Raman spectra in this compositional region is presented for the first time. Clear changes are observed in the Raman spectra. The progressive reduction in the intensity and final disappearance of the main Raman peak characteristic of the sesquioxide-based phase is observed with increasing zirconia contents. A corresponding increase in the intensity of the Raman features characteristic of the defective fluorite-type structure of yttria-stabilized zirconia solid solution was also observed. Raman features corresponding to both phases were present in a wide interval of compositions, from small addition of only 5 mol.% ZrO2, but no variation in the Raman shift of the main peaks was observed, reflecting that the Y–O bonding in the yttria-rich phase was not significantly affected with zirconia addition. Broadening of the peak was observed, and was attributed to the reduction of the coherent size of the yttria-based domains. The evolution of the spectra can be well explained using a two-phase model. Raman results indicate that substitution of yttria by zirconia in the lattice of the yttria-based sesquioxide domains is very limited.

The fabrication of a ternary eutectic ceramic composite by rapid quenching in the system Al 2 O 3 –Y 2 O 3 –ZrO 2 prompted us to study the solidification behavior and phase formation from melts of three-phase composites in the ternary oxide phase diagram. Solidified phases were determined by X-ray diffraction (XRD) and Raman spectroscopy. The occurrence of cation substitution in the stoichiometric phases, promoted by the rapid phase separation during quenching and the composition of solid solutions in the quenched composites were investigated. The results were used to determine the compositional limits of solid-phase regions, in order to construct a tentative subsolidus diagram for arc-image melted composites. The microstructural study indicates that it is feasible to fabricate ternary eutectic composites containing zirconia in the system by rapid quenching, even at cooling rates above 10 3 K s −1 . Eutectic composites with the zirconia-based ionic conductor phase have excellent prospects for a wide range of high temperature applications in technological devices.

The evolution of single-wall carbon nanotubes (SWNT) under hydrothermal treatment was investigated. Single-wall carbon nanotubes were used as the starting material and treated at temperatures between 200 and 800 °C and pressure of 100 MPa. The microstructural evolution was studied by means of transmission electron microscopy and Raman spectroscopy. After treatment at 800 °C, the single-wall nanotubes transformed completely to shorter multiwall carbon nanotubes and graphitic particles. The mechanism by which the observed evolution occurs is discussed.

A new fabrication technique of oxide film (BaTiO 3 film) has been investigated by the microwave–hydrothermal (M-H) method. The BaTiO 3 films were directly fabricated on Ti substrates at low temperature (100 °C) and short holding time (below 1 h). The obtained phases were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns showed that a single phase of BaTiO 3 film was formed on Ti plate. The formation process of BaTiO 3 film was explained based on the photographs of SEM.

Lithium ferrite, β-LiFe 5 O 8 , fine particles with a 100–120 nm size were successfully prepared by hydrothermal ball milling at the low temperature of 170 °C for 2 h without any post annealing. The lithium ferrite fine particle formation was confirmed by characterization using XRD, SEM, XPS and magnetization measurements. The experimental results strongly support the idea that ball milling can accelerate the reaction not only between the solid and solid phases but also between the solid and liquid phases. We believe hydrothermal ball milling can open a new era for the low temperature synthesis and fabrication of homogeneous fine particles both in composition and size.

LiMO2 (M=Ni and Co) films were directly fabricated in a concentrated LiOH solution at fixed temperatures, between 100 and 200 °C, using Soft Solution Processing. Film formation mechanism studies elucidate the key role of hydroxyl group in obtaining the LiCoO2 films and of electrochemical anodic process in obtaining the LiNiO2 films. It is also found that the formation of the LiMO2 (M=Ni and Co) is fully based on dissolution–precipitation model. Successful preparation of LiMO2 (M=Ni and Co) films using the newly designed experimental conditions based on the elucidation of the microstructuring mechanism shows a good example of how to introduce more economical, energy and material efficient, and environment-friendly synthetic route.

Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 :HA) with highly designed microstructures is required for bone filling materials and tissue engineering of cultured bones. This study deals with the shape control of HA particles and preparation of HA sheet from fibrous HA. Fibrous particles of HA with the aspect ratio of about 60 were prepared hydrothermally at 150 °C from the mixed solution of calcium acetate and phosphoric acid. The aspect ratio of the fibrous particles depended on the concentration and the value of Ca/P ratio of the mixed solution. The HA sheet must be a biostable material according to the soaking test with simulated body fluid.

Patterned crystalline films of lead sulfide (PbS) and cadmium sulfide (CdS) have been fabricated on a paper as one of organic sheets by a direct solution reaction at room temperature. A drop-on-demand inkjet printer, which is particularly interesting because it is a noncontact technique, was used to fabricate them. The projected drop of ink travels directly through air to the substrate where a reactant solution is immersed homogeneously. Then, the interfacial reaction between the two solutions can produce solid target materials with a desired pattern on the substrate. This is regarded as a simultaneous process of synthesis and patterning or an on-site fabrication of patterned ceramics. All of the films were fabricated at room temperature without any postfiring/postheating treatments. The optional patterning of these materials with widths of 100 μm has been successful. In addition, it was confirmed that the patterned materials were crystalline and had adequate optical properties. It indicates this method to be effective for direct patterning of various functional materials.

Recently, carbonized wood materials (CWM) impregnated with thermosetting resin have been proposed for many applications like heaters, electric leads, humidity and temperature sensors, etc. However, little is known about their chemical stability in water-containing environments. We have studied the behavior and stability of carbonized wood materials in aqueous solutions in a test tube type autoclave under hydrothermal conditions, between 100 and 800 °C and up to 100 MPa. The results showed an obvious weight loss due to hydrothermal corrosion and increased temperature. The samples were heavily corroded at temperatures higher than 500 °C. According to the results of Raman spectroscopy, amorphous carbon was selectively corroded.

We have studied the effect of melt quenching in the solidification behavior of ternary composites, for the Al2O3–Y3Al5O12 (YAG)–ZrO2 subsystem inside the ternary oxide system Al2O3–Y2O3–ZrO2. Ternary composites were prepared by melting and rapid quenching, in air, in an arc-image furnace. Solid phases were studied by XRD and Raman spectroscopy. Mutual substitution of the different cations in the solid phases is promoted by the rapid phase separation during quenching. The Al2O3–YAG–ZrO2 subsolidus region in the ternary diagram was determined for arc-image rapidly solidified composites.

A zirconia–yttria–niobia solid solution phase with fluorite structure (F) was prepared as a novel zirconia-based solid electrolyte for oxide fuel cells and oxygen sensors. The phase purity and electrical property of the prepared samples were investigated using powder X-ray diffractometry and two-probe ac conductivity, respectively. The electrical conductivity was studied as a function of temperature, P O 2 , and annealing time based on the phase relationship. The extended zirconia system, tri- and penta-valent cations substituted zirconia system, allowed to give a qualitative interpretation on the variation of the conductivity with the composition. In the range of F phase solid solution, it turned out that the activation energy for conduction was the more predominant factor in determining the conduction behavior rather than the concentration of oxygen-ion vacancies. The maximum conductivity could be found near the minimum concentration of the dopant to stabilize fluorite phase (cubic structure).

Li1−xNi1+xO2 and LiCoO2 films as cathodes for lithium rechargeable microbatteries were fabricated in a concentrated LiOH solution at 20–200°C using different Soft Solution-Processing methods. While LiCoO2 films can be obtained by a purely hydrothermal reaction, a supplementary electrochemical charge with the same hydrothermal conditions is necessary to produce Li1−xNi1+xO2 films. A film formation mechanism study elucidated the necessity of such different activation methods for the preparation of Li1−xNi1+xO2 and LiCoO2 films.

Pure SrSnO3 and (Ba1−xSrx)SnO3 with compositions (x=0, 0.25, 0.5, 0.75 and 1) were directly prepared by the polymerized complex (PC) technique based on a modified Pechini-type reaction route at the relatively low temperature of 600°C. Anhydrous citric acid (CA) was added to SnCl4.xH2O dissolved in ethylene glycol (EG). After complete dissolution, BaCO3 and SrCO3 powders were added according to the desired mole ratio of the solid solution, and the mixture was stirred at 80°C for several hours until the solution became transparent. This solution, with a molar ratio (Ba+Sr)/Sn/CA/EG=1/1/10/40, was heated at 130°C to produce a yellowish transparent resin without any precipitation. The pyrolysis of the resin at 350°C yielded a powder precursor for (Ba,Sr)SnO3. Pure SrSnO3 is found with a pseudo cubic structure, which has some deviation from the perfect cubic lattice. X-ray diffraction (XRD) indicated the formation of pseudo-cubic (Ba,Sr)SnO3 when the barium, strontium–tin precursor was heat treated in air at 600°C or above for 2 h. The solid solution of (Ba,Sr)SnO3 exhibited a transition from the ideal cubic structure to a pseudo cubic structure.

Phase equilibria in the Zr 0.5 Y 0.5 O 1.75 –Y 0.75 Nb 0.25 O 1.75 (1/4Y 3 NbO 7 ) system have been studied at 1700°C by a solid-state reaction. X-ray diffraction (XRD) analysis after heat treatment during 64 h indicated that all the compositions formed a cubic solid solution with a fluorite-type structure. The lattice parameter of the fluorite phase decreased with an increase in ZrO 2 content. Electrical conductivity for any given temperature increased with increasing ZrO 2 content, that is, with decreasing of Y and Nb, although the concentration of oxygen vacancies was kept constant in this system. Conductivity variation was explained by the association of oxygen ion with Nb and that of oxygen vacancies with Y, by comparing the diffuse-scattering intensity of each composition which was measured by XRD.

The breakdown of titanium oxide films anodically grown on Ti electrode under galvanostatic control in 0.5 M KOH solution by a hydrothermal–electrochemical method at the temperature of 150°C has been investigated. The breakdown of titanium oxide films play an important role in the formation of barium titanate (BT) film. The kinetic studies on barium titanate films hydrothermal–electrochemically fabricated in 0.25 M Ba(OH) 2 solution at 150°C show that the BT films could grow on both the Ti-oxide/BT interface and the BT/solution interface. AFM images show that the morphology and grain size of the BT films mainly depends on the dissolution–recrystallization process of the BT film. A schematic procedures have been proposed to interpret the mechanism of the BT formation extensively.

Lithium nickel oxide thin-film electrodes for lithium rechargeable microbatteries are directly fabricated from nickel substrates using the electrochemical-hydrothermal method in 4 M LiOH solution in the temperature range between 100 and 200°C and a current density between 0.1 and 5.0 mA/cm 2 for 20 h. The film properties show the obtained lithium nickel oxide films to be possible cathode films. However, the properties depend on the film formation conditions. Investigation of the effects of the film fabrication conditions gives fundamental information on film formation pathways and optimum conditions for lithium nickel oxide film formation. The successful separation of two different intermediate stages and the subsequent obtaining of lithium nickel oxide films confirms the film formation mechanism.

Cubic perovskite-type pure barium stannate, BaSnO 3 , powders were prepared using the polymerized complex technique at the relatively low temperature of 600°C. SnCl 4 · x H 2 O was first dissolved in ethylene glycol (EG) and anhydrous citric acid (CA) was then added. After complete dissolution, BaCO 3 powder was added and the mixture was stirred at 80°C for several hours until the solution became transparent, demonstrating the presence of Ba 2+ - and Sn 4+ –citric acid complexes. This solution, with molar ratio Ba/Sn/CA/EG=1:1:10:40, was heated at 130°C to produce a yellowish transparent resin without any precipitation via polymerization with citric acid and ethylene glycol including the complexes. Pyrolysis of the resin at 350°C yielded a powder precursor of BaSnO 3 . X-ray diffraction and Raman analysis indicated the formation of pseudo-cubic BaSnO 3 when the barium–tin precursor was heat treated in air at ≥600°C for 2 h. The product was identified as pseudo-cubic BaSnO 3 with lattice parameter a 0 =0.4118±0.0003 nm. The powder formed at 800°C consisted of faceted microcrystals 80–100 nm in size.

A fluorite-structured solid solution Y0.8Nb0.2O1.7 was prepared by a solid-state reaction at 1700°C and 1500°C. The electrical conductivity of Y0.8Nb0.2O1.7 prepared at 1700°C was studied as a function of temperature, PO2, and annealing time at 1000°C by an AC 2-probe method. The Y0.8Nb0.2O1.7 exhibited not only the highest conductivity among the samples in the Y2O3–Nb2O5 system but also a very wide PO2 range of ionic domain. The sample showed slightly decreased conductivity after the annealing time at 1000°C, but did not reveal any phase decomposition even after 370 h. These results suggest that Y0.8Nb0.2O1.7 is a promising material for an oxygen-ion conductor.

The formation of the ternary oxide thin films on nickel substrates in LiOH solution was studied under hydrothermal or electrochemical–hydrothermal conditions. While the purely hydrothermal treatment of nickel substrates at 150°C leads to the formation of Ni(OH) 2 films, by the use of the electrochemical–hydrothermal approach under supplementary galvanostatic charge with the same hydrothermal conditions, LiNiO 2 films are directly fabricated. The structural purity and chemical composition of the obtained films were confirmed by X-ray diffraction pattern analysis and X-ray photoelectron spectroscopy, respectively. The fabricated films show, according to X-ray diffraction, a good crystallinity without any post-synthesis annealing. In comparison with the fabrication of Ni(OH) 2 films by the hydrothermal method, it has been found that the electrochemical anodic process is necessary to obtain the desired LiNiO 2 films.

Highly crystallized BaMoO 4 films have been prepared on a molybdenum substrate in an alkaline solution containing barium ions at room temperature (25 °C). The film formation is based on a solution reaction assisted by an electrochemical dissolution of metal molybdenum. The film (thickness ~ 3 μm) was polycrystalline with a grain size of about 6 μm. The film morphology is related to the nucleation and growth behavior of the BaMoO 4 particles on a molybdenum metal substrate.

The basic features of Soft Solution Processing are discussed. Pioneering research carried out in our laboratory on in situ fabrication of morphology-controlled advanced ceramic materials by Soft Solution Processing (synthesis of double-oxide ABO 3 , ABO 4 films by hydrothermal, electrochemical, hydrothermal–electrochemical methods, coating of CaTiO 3 on TiAl, preparation of carbon films on SiC, hydroxyapatite whiskers and fine powders under hydrothermal conditions) is reviewed. Soft Solution Processing allows us to fabricate in aqueous solutions shaped/sized/oriented ceramics in only one step, without excess energies for firing/sintering or melting, and without expensive equipment, providing an environmentally friendly route for the preparation of advanced ceramic materials.

Metastable-stable phase diagrams of ZrO2-RO15 systems (R = Y, Sc and Er) are reviewed, noting the cation diffusionless transformations and reasonable diagrams are proposed. A tetragonal phase with an axial ratio of unity is interpreted to appear in the compositional region around 16 mol.% YO1.5.

Phase relations and melting temperatures in the PbF2-BiF3 system were studied by solid state reactions and DTA. A fluorite-type phase Pb1−xBixF2+x with 0

Using 18 O as a tracer, isotope exchange reaction was performed to determine the oxygen diffusion coefficients of Y 0.8 Ta 0.2 O 1.7 , Y 3 TaO 7 and Ho 3 TaO 7 over the temperature range 550–800°C. The diffusion coefficient in Y 0.8 Ta 0.2 O 1.7 was comparable to that in Ca-stabilized ZrO 2 . However, the diffusion coefficient in Y 3 TaO 7 and Ho 3 TaO 7 was several orders of magnitude lower than that in Y 0.8 Ta 0.2 O 1.7 and was in the same order as the data in Y 2 O 3 . These results were discussed in terms of crystal structures of these compounds.

BaTiO3 thin films have been prepared on Ti-substrates using Ba-acetate solutions by the hydrothermal–electrochemical method in newly constructed flow-system equipment. The synthesis parameters (temperature of 120–200°C, flow rate of 1–50 cm3 min−1) allow fabrication of single-phase films with grain size in the range of 50–340 nm by controlling nucleation and/or growth rates. The flow can be closed, enabling easy recycling of the solutions used. This processing route may serve as an inexpensive and environmentally friendly way of fabrication of single-phase BaTiO3 thin films as well as functionally graded ferroelectric materials.

A series of 3R 2 O 3 ·Ta 2 O 5 (R 3 TaO 7 , R=rare earth) samples were synthesized in various conditions; i.e. solid-state reactions at 1350°C or 1700°C, melting and cooling, rapid quenching of the melt and annealing at 1700°C, etc. According to powder X-ray diffraction, the crystal structure of R 3 TaO 7 is more symmetric and disordered for the smaller ionic radius of the R 3+ ion, changing from weberite-type orthorhombic to pseudo-cubic to pyrochlore-type cubic to fluorite-type cubic. We prepared a series of R 3 TaO 7 single crystals by a floating-zone method for further investigation of R 3 TaO 7 structures. Although the powder X-ray diffraction patterns of R 3 TaO 7 showed a cubic fluorite structure for the smaller R 3+ ions, single-crystal X-ray diffraction gave diffraction spots forbidden by the fluorite face-centered-cubic structure. This observation shows that the R 3+ and Ta 5+ ions are ordered in R 3 TaO 7 even for the smaller R 3+ ions.

The equilibrium solidus phase diagrams in fluorite-related systems of ZrO2−CeO2 and SrF2−LaF3 are established by hydrothermal techniques in aqueous LiCl solution at below 1400°C and 750°C, respectively. The solid solutions of cubic, tetragonal and monoclinic phase are produced in the system ZrO2−CeO2. The tetragonal phase decomposes to monoclinic and cubic phase at the eutectoid temperature of 1050°C±50°C. The coexistent boundary of the tetragonal and cubic phase are about 18 and 70 mol% CeO2, 16 and 80 mol% CeO2, at 1400°C and 1200°C, respectively. The coexistent boundary of the monoclinic and cubic phase are about 1.5 and 88 mol% CeO2, 1.5 and 98 mol% CeO2, at 1000°C and 800°C, respectively. The solid solutions of cubic and hexagonal phases are produced in the system SrF2−LaF3. The coexistent boundaries of the cubic and hexagonal phases are about 47 and 94 mol% LaF2, 47 and 96 mol% LaF3, and 46 and 98 mol% LaF3 at 750°C, 650°C and 500°C, respectively.

The solubility in the system SrF 2 -LaF 3 were studied by solid state reaction (1400°, 1300°, 1000° and 750°C) using Pt capsules and hydrothermal reaction (750°, 650° and 500°C) using the 10wt% LiCl or other solutions. Starting samples were (I) mixed and (II) fired samples of SrF 2 and LaF 3 powders (99.9%). At any temperatures, a linear relation between the composition and the lattice parameter of the solid solutions of each phase (SrF 2 ss or LaF 3 ss) could be obtained corresponding to the Vegard's law. The hydrothermal reaction was very effective to accelerate the reactions to reach to the phase equilibria; 1 day by hydrothermal and 23(7+7+9) days by solid state reactions at 750°C. The solubility limits in SrF 2 ss were 48,48,47,47 and 46 mol% LaF 3 , and those in LaF 3 ss were 15,11, 6,4 and 2 mol% SrF 2 at 1400°, 1000°,750°,650° and 500°C, respectively by X-ray measurements.

The phase relations in the system ZrO 2 YF 3 YO 1.5 have been investigated. Solid state reactions were carried out using encapsulated samples to prevent compositional changes. At 1300°C the ternary system contains 2 single-phase regions of tetragonal (T) and cubic (C) phases, 3 two-phase regions of T+YF 3 , C+YF 3 and C+T, and 1 three-phase region of C+T+YF 3 . The solubility limits determined from lattice parameters were found to be 8.5 mol% YOF along the ZrO 2 YOF join for the tetragonal phase, and 4.5 mol% YF 3 for the cubic phase, respectively.

The detailed structure investigations of Zr2Gd2O7 with pyrochlore- and fluorite-type structures have been carried out by X-ray single crystal method at room temperature. The bond distances between cations and oxide ions versus the site population for cations reasonably support that the fluorite phase is made up of the structure with microdomains of the pyrochlore. Sharp fundamental and diffuse superstructure reflections of the pyrochlore are interpreted assuming that anti-phase domain boundaries lie parallel to the &{211} and that domain sizes are not uniform. It should be proposed that the layers composed of the 48f site oxide ions are anti-phase boundaries. The probability density function maps and effective one-particle potentials of the pyrochlore structure reveal that the magnitudes of anharmonic thermal motions for the 48f site oxide ions are large toward the unoccupied 8b site. Compared to the s-pyrochlore phase (with sharp superstructure reflections), the 48f site oxide ions of the d-pyrochlore (with diffuse superstructure reflections) and fluorite phases have larger temperature factors and gentler potential curves. This is due to that the anti-phase domains are coherent each other and that their electron density distributions are the averages of individual domains.

Critical review of the phase diagrams proposed previously suggested incomplete establishment of the phase equilibria in the system ZrO2-CeO2 below 1400°C. Application of hydrothermal techniques enabled us to attain the equilibria in this system. The tetragonal SS (solid solution) was no longer stable below 1000°C, where it decomposed into the stable monoclinic SS and cubic SS. The solubility limit of the tetragonal or cubic SS was 23 wt%(18 mol%) CeO2 or 79 wt%(73mol%) CeO2, respectively at 1400°C. That of the monoclinic or cubic SS was 5 wt%(3.5 moI%) CeO2 or 96 wt%(95mol%) CeO2, respectively at 800°C. Thermochemical calculation appears to make it possible to predict true equilibria in this system.

The polymorphism of “R 3 TaO 7 ” compounds, which were regarded to be stable phases as 3:1 compounds in the R 2 O 3 Ta 2 O 5 system (R=rare earth), are discussed in terms of lattice energies, calculated by the Ewald method. The phase with higher crystal symmetry has the negatively smaller lattice energy, so that the phase with higher symmetry become less stable; Cmcm>C222 1 >Fd3m>Pm3m>Fm3m. This is in accordance with experimental observations.