Cubic-anvil High-pressure Apparatus Research Articles

High pressure synthesis and magnetic properties of corundum-type Ga1-xAlxFeO3 (x = 0, 0.25, 0.5)

Metastable phases of Ga1-xAlxFeO3 (x = 0, 0.25, 0.5) have been prepared under high pressure (4.5 GPa) and high temperature (1000 °C) using a cubic-anvil high pressure apparatus. X-ray diffraction studies show that application of pressure transforms the structure of these compounds from the polar Pna21 to the non-polar R3̅c phase. Intriguingly, the orthorhombic phase of the compound with x = 1.0, synthesized at ambient pressure decomposes into their constituent oxides, Al2O3 (R3̅c) and Fe2O3 (R3̅c) under the same conditions of pressure and temperature. Magnetization measurements reveal antiferromagnetic ordering with a weak ferromagnetism below TN ~ 450 K, 590 K and 650 K, respectively. All these oxides exhibit a spin glass behavior at low temperatures. Analysis of ac susceptibility measurements indicate the existence of a cluster spin glass phase below T* ~ 45, 40 and 43 K respectively for x = 0, 0.25, 0.5. Such a re-entrant spin glass behavior arises due to antiferromagnetic interactions among the disordered Fe3+ ions in the octahedral site of the corundum structure.

In-situ observation of synthesizing process of MmxCo4Sb12 utilizing x-ray diffraction under high temperatures and high pressures

The antimony-based partially-filled skutterudite compound MmxCo4Sb12 (Mm=mischmetal) are expected for n-type thermoelectric materials with high-perfomance and low-cost. In order to prepare high-quality samples of the compound, synthesizing processes at high pressures and high temperatures have been studied by means of in-situ x-ray diffraction measurements using synchrotron radiation and a cubic-anvil high pressure apparatus. In series of the experiments, we could obtain the optimum condition for synthesizing the compound under high pressure.

Electrical conductivity of amphibole-bearing rocks: influence of dehydration

We investigated the electrical conductivity of amphibole-bearing rocks under the conditions of the middle to lower crust. Alternating current measurements were performed in the frequency range of 10–106 Hz in a cubic-anvil high-pressure apparatus at 0.5–1.0 GPa and 373–873 K. The electrical conductivity of these rocks is weakly temperature dependent below ~800 K with modest anisotropy and relatively low conductivity (~5 × 10−3 S/m at ~750 K with the activation enthalpy of 64–67 kJ/mol). However, the electrical conductivity starts to increase with temperature more rapidly above ~800 K (activation enthalpy of 320–380 kJ/mol). The infrared spectroscopy observations indicate that dehydration occurs in this high temperature regime. The observed high activation enthalpy and the reproducibility suggest that the enhanced conductivity is not due to the direct effect caused by the generation of conductive fluids. Dehydration of amphibole is associated with the oxidation of iron (from ferrous to ferric), and we suggest that the increased conductivity associated with dehydration is caused by oxidation. This effect may explain high electrical conductivity observed in some regions of the continental crust.

A Raman study of nylon 6 annealed under high pressure

AbstractUsing a cubic-anvil high pressure apparatus, nylon 6 samples were annealed under 400 MPa to 1.5 GPa. The structure changes of nylon 6 are studied by the methods of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and Raman spectra. Compared with sample prepared at ambient pressure, high pressure treatment makes the hydrogen-bonded sheets pack more closely and thus enhanced CH2 vibration out of the hydrogen-bonded sheets. After high pressure treatment, it is observed that all changes of C-C related vibration modes in nylon 6 are similar with ones in nylon series when the CH2 sequence number increased, from which it is deduced that high pressure treatment reduces the effects of amide group on the chain conformation of nylon 6.

New intermetallic MIrP (M=Ti, Zr, Nb, Mo) and MgRuP compounds related with MoM'P (M'=Ni and Ru) superconductor

Using a cubic-anvil high-pressure apparatus, ternary iridium phosphides MIrP (M=Ti, Zr, Nb, Mo) and MgRuP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 Gpa and above 1523 K for the first time. The structure of these compounds prepared at high-pressure has been characterized by X-ray powder diffraction. Diffraction lines of these compounds are assigned by the index of the Co2Si-type structure. The electrical resistivity and the d.c magnetic susceptibility of MIrP (M=Ti, Zr, Nb, Mo) have measured at low temperatures. Unfortunately, no superconducting transition for MIrP (M=Ti, Zr, Nb, Mo) and MgRuP are observed down to 2 K.

New intermetallic MIrP (M=Ti, Zr, Nb, Mo) and MgRuP compounds related with MoM'P (M'=Ni and Ru) superconductor

Using a cubic-anvil high-pressure apparatus, ternary iridium phosphides MIrP (M=Ti, Zr, Nb, Mo) and MgRuP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 Gpa and above 1523 K for the first time. The structure of these compounds prepared at high-pressure has been characterized by X-ray powder diffraction. Diffraction lines of these compounds are assigned by the index of the Co2Si-type structure. The electrical resistivity and the d.c magnetic susceptibility of MIrP (M=Ti, Zr, Nb, Mo) have measured at low temperatures. Unfortunately, no superconducting transition for MIrP (M=Ti, Zr, Nb, Mo) and MgRuP are observed down to 2 K.

In-situ observation of crystallization of TSb3 (T=Co, Rh and Ir) under high temperatures and high pressures

Synthesizing processes of the binary antimony-based skutterudite compounds, CoSb3, RhSb3 and IrSb3 at high pressures and high temperatures have been studied by means of in-situ x-ray diffraction measurements using synchrotron radiation and a cubic-anvil high-pressure apparatus. In series of the experiments, we could obtain the synthesis condition of these compounds under high pressure.

Finite-element analysis on performance and shear stress of cemented tungsten carbide anvils used in the China-type cubic-anvil high-pressure apparatus

Stress distribution in cemented tungsten carbide (WC) anvils is of primary interest in high pressure research, but is very difficult to determine experimentally. We have performed finite-element simulations to study the performance and the shear stress distribution of WC anvils used in the China-type cubic-anvil high pressure apparatus (SPD-6×2000). Our results show that in order to avoid failure cracks in high-stress areas, the maximum shear stress should be lower than 3.17 GPa for the WC anvils (8% cobalt). The simulations have been verified by high-pressure experiments. Our method of analyzing stress distribution helps in evaluating the ability of WC anvils, and would aid in designing a new anvil to enhance performance.

極低温用超小型キュービックアンビル圧力発生装置の開発

Effects of pressure on the physical properties are very important for understanding highly correlated electron systems, in which pressure-induced attractive phenomena such as superconductivity and magnetically ordered non-Fermi liquid have been observed. Up to now, many scientists have developed a lot of high pressure apparatus for each purpose. In this paper, we present the very small “palm cubic-anvil high-pressure apparatus” for precise electric transport measurements under high pressure up to 8 GPa. The most outstanding characteristic of this pressure cell is its compactness. This cell enables us to measure absolute values of electrical resistivity, magneto-resistance and Hall coefficient at various temperatures. The details of our palm cubic high-pressure apparatus are introduced, and some neutron experimental results at room temperature are discussed.

Intermetallic compound MoIrP related with MoRuP and MoNiP superconductor

Ternary iridium phosphide MoIrP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 GPa and above 1873 K using a cubic-anvil high-pressure apparatus for the first time. The structure of this material prepared at high pressure has been characterized by X-ray powder diffraction. All the diffraction lines are assigned by the index of the Co 2Si-type structure. The electrical resistivity and the DC magnetic susceptibility of MoIrP have been measured at low temperatures. Unfortunately, no superconducting transition is observed down to 2 K.

Thermal Expansion of Filled Skutterudite Compound SmRu4P12

The compound SmRu4P12 crystallized in the cubic filled skutterudite-type structure with space group Im 3 (Th, No. 204) has attracted much interest because it exhibits a metal–insulator (M–I) transition at TMI 1⁄4 16:5K. PrRu4P12 is also known to undergo a M–I transition at TMI 60K. The M–I transition in PrRu4P12 has been considered to result from a charge-density-wave (CDW) transition caused by the perfect three dimensional nesting of the Fermi surface. The mechanism of M–I transition in SmRu4P12 has been, however, believed to be different from that in PrRu4P12. The M–I transition of SmRu4P12 has magnetic origin because the magnetic susceptibility clearly shows an anomaly at M–I transition, unlike PrRu4P12. 2) The specific heat at zero field shows a -shaped peak anomaly at the M–I transition; this is a second order transition. Recent work has revealed that this M–I transition occurs in fact in two successive steps. The specific heat exhibits a double peak in magnetic field. In 9 T two anomalies clearly appear at 13K (TN) and 17K (TMI). The temperature derivative of the electrical resistivity d ðTÞ=dT and of the magnetization dMðTÞ=dT also exhibit two anomalies at the same positions as the specific heat peaks. The lattice constant and the magnetic properties show Sm ion in this compound to be trivalent with J 1⁄4 5=2. The magnetic entropy estimated at zero field reaches R ln 4 at TMI. 5) This indicates that the crystalline electric field (CEF) ground state is 67 quartet (4 f , J 1⁄4 5=2) in the cubic point group Th, which is consistent with the theoretical prediction. 67 is the same as 8 quartet in Oh. 8) 67 has both magnetic and orbital degree of freedom. The existence of a double anomaly can be ascribed to two successive transitions on cooling: orbital ordering, then magnetic ordering such as in CeB6. 9) The temperature dependence of the magnetization MðTÞ shows an upturn at TMI and a round peak near 15K below TMI. 6) TMIðHÞ slightly increases (H-dependence) with increasing magnetic field H. This behavior is consistent with the upturn in MðTÞ considering thermodynamic relations for second order transition. On the other hand, MðTÞ shows a steep drop below TN and TN monotonically decreases with H. Such behavior in the phase diagram is often observed in compounds which show antiferro-quadrupolar (AFQ) ordering. The possibility of AFQ ordering in SmRu4P12, therefore, has been argued due to these reasons. On the other hand, recent ultrasonic measurements suggest a breakdown of the time reversal symmetry below TMI. 11,12) This result and group-theoretical considerations give a new scenario for the mechanism of M–I transition, which is due to the coupling between dipole moment and octupole moment. In spite of much discussion as stated above, the nature of M–I transition in SmRu4P12 is still an enigma. In this paper, we report thermal expansion measurements of SmRu4P12 in applied magnetic field, which have been performed to investigate the properties of the successive phase transitions at TN and TMI. Single-phase polycrystalline SmRu4P12 was prepared at high temperature and high pressure using a wedge-type cubic-anvil high-pressure apparatus. The pressure-cell assembly is similar to that used for the synthesis of black phosphorus. The compound was prepared by reaction of stoichiometric amounts of each metal and red phosphorus powder at 4GPa. The reaction temperature and time were 1100 C and 30min, respectively. The sample was characterized by powder X-ray diffraction using CuK 1 radiation. The sample was shaped into a cylindrical shape with 3.4mm diameter and 4.1mm length (L). The coefficient of linear thermal expansion 1⁄4 ð1=LÞðdL=dTÞ in the magnetic field up to 8 T was measured using a sensitive three-terminal capacitance cell, with a detection limit L=L 10 . We show the relative change of thermal expansion L=L in SmRu4P12 as a function of temperature at various fields (Fig. 1). Vertical dotted lines indicate transition temperatures of TMI 1⁄4 16:5K and TN 14K at zero field, determined by 1⁄4 ð1=LÞðdL=dTÞ. Experimental values are normalized to 22K. Below TMI, the sample length contracts, L=L 1:0 10 , with decreasing temperature at zero

Thermoelectric Properties of CeRu4P12 and CeOs4P12 with Filled Skutterudite-Type Structure

The thermoelectric properties of hybridized band-gap semiconductor CeRu4P12 and CeOs4P12 with the filled skutterudite-type structure have been studied. Skutterudites have been identified recently as promising candidates for thermoelectric applications such as in solid-state refrigeration or power generation. Polycrystalline samples of CeRu4P12 and CeOs4P12 were synthesized with a high-pressure cell under high temperature using a cubic-anvil high-pressure apparatus. The samples were characterized by X-ray diffractometry. The Seebeck coefficient, electrical resistivity, Hall coefficient and thermal conductivity were measured. The Seebeck coefficients of both compounds are significantly large and the power factor values are of the order of 10-3 W/mK2. The effect of hybridization between the Ce 4f and pnicogen p states or transition metal d states is important for determining the thermoelectric properties of this system.

The effect of phase transition on the compressional wave velocity for a trachybasalt at high temperature and high pressure

Compressional wave velocities in a trachybasalt, from Yichuan County, Henan Province, have been measured at 2.0 GPa and up to 1 350°C in a YJ-3000 t cubic-anvil highpressure apparatus. The run products have been gained at the same pressure but different temperatures. he observation of the thin sections of the run products indicates that, corresponding to the variation of the compressional wave veloctty in the trachybasalt, the phase transition has taken place. The relationship between the change of the compressional wave velocity and the hydrous mineral dehydration, solid-solid phase transformation and partial melting has been discussed. The experimental data presented here are of great importance to elucidating the geological process in the earth’s interior.

Superconductivity of the ternary ruthenium compounds HfRuP and ZrRuX (X = P, As, Si or Ge) prepared at a high pressure

Abstract Using a wedge-type cubic-anvil high-pressure apparatus, equiatomic Ru compounds HfRuP and ZrRuX (X = P, As, Si or Ge) with layered structures have been prepared at high temperatures and high pressures. The super-conducting transition teinperatures T c of these compounds were 12 K for HfRuP, 13 K for ZrRuP, 11.5K for ZrRuAs, 12.2 K for ZrRuSi and 10.5 K for ZrRuGe. The electrical resistivities of these ternary Ru compounds have been measured as functions of applied magnetic field at low temperatures. The upper critical fields H c2 of HfRuP, ZrRuP, ZrRuAs, ZrRuSi and ZrRuGe are 14, 16, 14.1, 14.5 and 8.3 T respectively. The value of H c2 for ZrRuP is the highest among the equiatomic Ru compounds. The coherence lengths of these compounds are 48.5 A for HfRuP, 45.4 A for ZrRuP, 48.3 A for ZrRuAs, 47.7 A for ZrRuSi and 63.0 A for ZrRuGe. The superconductivity of the ternary Ru compounds is discussed.

Superconductivity of the ternary ruthenium compounds HfRuP and ZrRuX (X= P, As, Si or Ge) prepared at a high pressure

Abstract Using a wedge-type cubic-anvil high-pressure apparatus, equiatomic Ru compounds HfRuP and ZrRuX (X = P, As, Si or Ge) with layered structures have been prepared at high temperatures and high pressures. The super-conducting transition teinperatures T c of these compounds were 12 K for HfRuP, 13 K for ZrRuP, 11.5K for ZrRuAs, 12.2 K for ZrRuSi and 10.5 K for ZrRuGe. The electrical resistivities of these ternary Ru compounds have been measured as functions of applied magnetic field at low temperatures. The upper critical fields H c2 of HfRuP, ZrRuP, ZrRuAs, ZrRuSi and ZrRuGe are 14, 16, 14.1, 14.5 and 8.3 T respectively. The value of H c2 for ZrRuP is the highest among the equiatomic Ru compounds. The coherence lengths of these compounds are 48.5 Å for HfRuP, 45.4 Å for ZrRuP, 48.3 Å for ZrRuAs, 47.7 Å for ZrRuSi and 63.0 Å for ZrRuGe. The superconductivity of the ternary Ru compounds is discussed.

Superconductivity of MRhSi (M=Ti, Zr and Hf) prepared at high pressure

Using a wedge-type cubic-anvil high pressure apparatus, ternary rhodium silicides MRhSi (M=Ti, Zr and Hf) and alloys ZrRh 1− x Ru x Si ( x=0.1, 0.3 and 0.5) with a Co 2P-type orthorhombic structure have been prepared by reaction of stoichiometric amounts of each metal and silicon powders at around 4 GPa and above 1200°C. The electrical resistivity and the d.c. magnetic susceptibility of the ternary rhodium silicides and the alloys have been measured at low temperatures. Superconducting transition temperatures ( T c ) in MRhSi (M=Ti, Zr and Hf) are 5.1, 10.3 and 2.3 K, respectively. These ternary rhodium silicides are new superconductors. The T c (=10.3 K) of ZrRhSi is highest among many compounds with the Co 2P-type structure.

Electrical conductivity and superconductivity of metal phosphides with skutterudite-type structure prepared at high pressure

Metal phosphides with skutterudite (CoAs 3 )-type structure have been prepared using a wedgetype cubic-anvil high pressure apparatus. NiP 3 , LaRu 4 − x Os x P 12 ( x : 0, 1, 2, 3, 4) and CeRu 4 P 12 were synthesized at around 1100 °C and 4 GPa. The electrical conductivity and superconductivity of these metal phosphides were studied at low temperatures. The resistivity of NiP 3 was 1.6 × 10 −3 Ω cm at room temperature and decreased with decreasing temperature. A magnetic susceptibility of the phosphide showed Pauli paramagnetism. NiP 3 behaves as a metal. The resistivity of CeRu 4 P 12 increased with decreasing temperature. The semiconductive behavior was observed for this phosphide. The superconductivity of LaRu 4 P 12 , LaRu 3 OsP 12 and LaRu 2 Os 2 P 12 was observed at around 7 K. The magnetic field dependence of the T c was studied for LaRu 4 P 12 . The upper critical field ( H c 2 ) of LaRu 4 P 12 was 3.65 tesla at 0 K. The superconductivity of LaOs 4 P 12 was not found above 2 K. The electronic states and the superconductivity of the metal phosphides with skutterudite-type structure are discussed.

Large volume high pressure research using the wiggler port at NSLS

Abstract A DIA-type cubic-anvil high pressure apparatus (SAM-85) has been interfaced with white x-ray radiation from the superconducting wiggler port of the National Synchrotron Light Source at Brookhaven National Laboratory. Energy-dispersive x-ray diffraction measurements can be obtained for samples with dimensions of the order of 1 mm as a function of pressure and temperature utilizing x-ray energies of up to100 keV. The sample environment is examined. Pressure is uniform in the sample chamber to within 0.1 GPa, and temperature is constant in the scattering volume to within 5°C.A method is defined for determining deviatoric stress. We find that for a sample containing NaCl and Au, the deviatoric stress increases to about 0.3 GPa as pressure increases to 1.5 GPa and then remains constant, probably reflecting the strength of the sample. Upon heating, the deviatoric stress quickly approaches zero. Presented at the IUCr Workshop on ‘Synchrotron Radiation Instrumentation for High Pressure Crystallography’, ...

Metal-silicate-water reaction under high pressure. II. Partition of Fe, Ni and Co between metal and silicate

The systems (Fe, Ni)-silicate-water, (Fe, Co)-silicate-water and (Fe, Ni)-silicate-water-sulfur were investigated at around 5 GPa and 1000–1500°C by using a tetrahedral-anvil and cubic-anvil high-pressure apparatus. The quenched samples showed the coexistence of olivine, pyroxene and metal. The distribution behavior of Fe, Ni and Co between metal-olivine and metal-pyroxene was measured in these quenched samples. The observed values of apparent partition coefficients, K′(FeNi) and K′(FeCo), were approximately 40–100 and 10–30, respectively. These values are 10–100 times larger than the estimated value for the Earth's core and mantle, and would indicate that the Earth could not be in equilibrium as a total system. To explain the observed transition metal abundance in the Earth, it is necessary to consider the accretion process and the core formation processes in the partially molten layer of the proto-Earth.

High-pressure phase transition in MnTiO3 from the ilmenite to the LiNbO3 structure

Crystals of a high-pressure phase of MnTiO3 have been synthesized at pressures of 60 kbar using the SAM-85 cubic-anvil high pressure apparatus. Although all crystals examined were twinned on (10 $$\bar 1$$ $$\bar 2$$ ), a set of diffraction intensities that are essentially unaffected by the twinning were obtained. Three possible structure models were considered: (1) the corundum (completely disordered Mn and Ti), (2) the partially-disordered ilmenite, and (3) the LiNbO3 structures. The R factors of the corundum and the disordered ilmenite models were much larger than that of LiNbO3. Using structure factors unaffected by twinning, the final LiNbO3-type refinement gave R w=0.037 and R=0.034. The averaged bond lengths for Mn-O and Ti-O were consistent with ones calculated using Shannon and Prewitt's (1969) radii. The study concludes that MnTiO3 II actually has an ordered LiNbO3-type structure rather than the disordered one as reported previously. From the analysis of the two MnTiO3 structures, the transition can be related to a cation reordering process, in which half of the cations participate, accompanied by the rotation of oxygens to accommodate the cations.