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We synthesize PbMn7O12 perovskite under high-pressure (6 GPa) and high-temperature (1373 K) conditions and investigate its structural, magnetic, dielectric, and ferroelectric properties. We find that PbMn7O12 exhibits rich physical properties from interplay among charge, orbital, and spin degrees of freedom and rich structural properties. PbMn7O12 crystallizes in space group R3 near room temperature and shows a structural phase transition at TCO = 397 K to a cubic structure in space group Im3; the Im3-to-R3 transition is associated with charge ordering. Below TOO = 294 K, a structural modulation transition associated with orbital ordering takes place. There are two magnetic transitions with Neel temperatures of TN1 = 83 K and TN2 = 77 K and probably a lock-in transition at TN3 = 43 K (on cooling). There is huge hysteresis on specific heat (between ∼37 and 65 K at 0 Oe), dielectric constant (between ∼20 and 70 K at 0 Oe), and dc and ac magnetic susceptibilities around the lock-in transition. Sharp diel...

We investigate the synthesis of a thallium scandate, TlScO3, under high-pressure (6–7.7 GPa) and high-temperature (1373–1773 K) conditions. At 6 GPa, a LiNbO3-type phase appears in a narrow temperature range and in mixtures with other phases. At 7.7 GPa and 1673 K, a new LiNbO3-type oxide is found with a composition of (Tl1–xScx)ScO3 and x ≈ 0.26 as determined by structural analysis from X-ray powder diffraction data. It crystallizes in space group R3c (No. 161) with lattice parameters of a = 5.50283(7) A and c = 14.4606(2) A. It is stable at least up to 800 K at ambient pressure. The point-charge model gives an electric polarization of 60 μC/cm2. First-principles calculations show that centrosymmetric ilmenite-type and polar LiNbO3-type structures of stoichiometric TlScO3 have almost the same lowest energy, and the next stable structure is a GdFeO3-type perovskite structure.

CdMn7O12 (I) and SrMn7-xFexO12 (x = 0 (II), 0.08, 0.5) perovskites are prepared by hot pressing of stoichiometric mixtures of Mn2O3, MnO2, and CdO as well as Mn2O3, Fe2O3, and 4H-SrMnO3, resp.

New nanoporous iron oxide nanoparticles with superparamagnetic behavior were successfully synthesized from Prussian blue (PB) nanocubes through a thermal conversion method and applied to the intracellular drug-delivery systems (DDS) of bladder cancer cells (i.e., T24) with controlled release and magnetic guiding properties. The results of the MTT assay and confocal laser scanning microscopy indicate that the synthesized iron oxide nanoparticles were successfully uptaken by T24 cells with excellent biocompatibility. An anticancer drug, that is, cisplatin, was used as a model drug, and its loading/release behavior was investigated. The intracellular drug delivery efficiency was greatly enhanced for the cisplatin-loaded, PB-derived, magnetic-guided drug-delivery system compared with the non-drug case. The synthesized nanomaterials show great potential as drug vehicles with high biocompatibility, controlled release, and magnetic targeting features for future intracellular DDS.

The title compound is prepared from a stoichiometric mixture of Mn2O3 and Tl2O3 (Au capsules, 6 GPa, 1500 °C, 2 h) and characterized by powder and single crystal XRD, magnetic, specific heat, and electrical resistivity measurements, Moessbauer spectroscopy, and DFT calculations.

The title compound is prepared by high pressure/high temperature reaction of stoichiometric mixtures of Bi2O3, CrO2, and CrO3 (Au capsules, 6 GPa, 1570 K, 2 h).

The title compounds are prepared from stoichiometric mixtures of In2O3 or Sc2O3 and Rh2O3 (Au capsules, 6 GPa, 1500 K, 2 h).

BiRhO3 (I), LuRhO3 (II), and NdRhO3 (III) are prepared by solid state reaction of stoichiometric mixtures of M2O3 (M: Bi, Lu, Nd) and Rh2O3 (Au capsules, 6 GPa, 1600 °C for (I), 1300 °C for (II) and (III), 2 h).

Review: recent experimental and theoretical results on BiMO3 with M: Al, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Ga, In, and Rh; 128 refs.

BiGaxM1-xO3 (M: Cr, Mn, Fe) solid solutions are prepared from stoichiometric mixtures of Bi2O3, M2O3, and Ga2O3 (for M: Cr, Fe: 6 GPa, 1700 K; for M: Mn: 1300 K, 2 h) and characterized by powder XRD.

The title compounds are prepared from stoichiometric mixtures of Bi2O3, PdO, and KClO4 (BiPd2O4), or PbO2 and PdO (PbPd2O4) in Au capsules at 6 GPa and 1500 K (2 h).

The title compounds are prepared from stoichiometric mixtures of In2O3, Sc2O3, and Cr2O3 (Au capsule, 6 GPa, 1500 K, 2 h).

BiFe1-xMnxO3 (0.0 ≤ x ≤ 0.4) solid solutions are prepared from stoichiometric mixtures of Bi2O3, Fe2O3, and Mn2O3 at 1143 K for 2 h (ambient pressure samples), and at 6 GPa and 1400 K for 90 min (high pressure samples).

An oxygen-deficient BiMnO2.81 sample in bulk form is prepared by low-temperature vacuum reduction of stoichiometric BiMnO3 (10-4—10-3 Pa, 570—600 K, 5 h).

The LiNbO3 phase (LN-phase) of the title compound with x = 0.143 and M: Fe0.5Mn0.5 is synthesized from stoichiometric mixtures of In2O3, Mn2O3, and Fe2O3 (Pt capsule, 6 GPa, 1773 K, 30 min).

InMn1-xGaxO3 (0 ≤ x ≤ 1) solid solutions are prepared from stoichiometric mixtures of In2O3, Ga2O3, and Mn2O3 (Au capsules, 6 GPa, 1373 K, 30 min) and characterized by powder XRD, and magnetic and dielectric measurements.

In1-xMnO3-1.5x (x = 0.1, 0.2, 0.3, 0.4, 0.5) samples are prepared from stoichiometric mixtures of In2O3 and Mn2O3 (Pt capsules, 6 GPa, 1773 K, 40 min) and characterized by powder XRD and magnetic measurements.

Single crystals of the new title compound are prepared by a flux method from mixtures of Ca3OsO6 (obtained from stoichiometric amounts of CaO2 and Os, Pt capsule, 6 GPa, 1500 °C, 1 h), LiCl, and KCl in a mass ratio of 1:5:2 (Pt crucible, 750 °C, 12 h).

8-Vinyl-, styryl-, (l-propenyl)thioquinolines, 8-quinoline vinyl sulfoxide, and 8-quinoline vinyl sulfone have been synthesized. Their structures have been studied by molecular mechanics and quantum chemistry.

The enantiopure p -toluenesulfinimines were found to be efficient as chiral imine equivalents in the high temperature Reformatsky-type additions with BrZnCF 2 COOEt affording an efficient approach to the enantiomerically pure α,α-difluoro-β-amino acids. High chemical and stereochemical yields (drs>9:1, and as high as 99:1) render this method immediately useful for preparing the target amino acids.

A new phosphate, Ca9FeD(PO4)7, with a whitlockite-like structure was synthesized by treating Ca9Fe(PO4)7 with D2 at 820 K. Mossbauer spectroscopy showed that the oxidation state of Fe in Ca9FeD(PO4)7 is +2. Ca9FeD(PO4)7 was paramagnetic in a temperature range from 5 to 300 K with an effective magnetic moment of 4.97 μB per Fe2+ ion. The infrared spectrum of Ca9FeD(PO4)7 exhibited a broad absorption band due to an O−D stretching vibration at 2225 cm-1 in addition to bands assigned to PO4 groups. Ca9FeD(PO4)7 was stable under an Ar atmosphere up to 840 K. Above this temperature, it decomposed to a β-Ca3(PO4)2-like phase, Ca9.333Fe1.167(PO4)7, as well as β-Ca2P2O7 with releasing D2O and keeping the oxidation state of +2 for Fe. Ca9FeD(PO4)7 liberated D2O in air above ca. 720 K to produce Ca9Fe(PO4)7. Second-harmonic-generation signals, I2ω/I2ω(SiO2), in Ca9FeD(PO4)7 (ca. 0.15) were by a factor of ca. 17 less than ca. 2.5 in Ca9Fe(PO4)7. Rietveld analysis of time-of-flight neutron diffraction data for Ca9FeD(...

Na2OsO4 crystals were grown by a NaCl flux method under high pressure. It crystallizes in the Ca2IrO4-type structure without having additional elements or metal vacancies, which are usually accommodated. It appears that Na2OsO4 is a metal-stoichiometric Ca2IrO4-type compound never been synthesized to date. Na2OsO4 has the octahedral environment of Os6+O6 so that the electronic configuration is 5d2, suggesting the magnetic S=1 ground state. However, magnetization, electrical resistivity, and specific heat measurements indicated that the non-magnetic S=0 state is much likely for Na2OsO4 than the S=1 state. Band structure calculations and the structure analysis found that the disagreement is probably due to the statically uniaxial compression of the OsO6 octahedra, resulting in splitting of the t 2 g band.

High-pressure structural properties of multiferroic perovskite-type BiFeO3 have been investigated by high-resolution synchrotron X-ray powder diffraction at room temperature up to 9.7 GPa. BiFeO3 shows rather complicated structural behavior. The ambient-pressure ferroelectric R3c phase transforms to an orthorhombic phase OI at around 4 GPa during compression. The OI phase is characterized by a superstructure √2ap × 3√2ap × ap, where ap is the parameter of the cubic perovskite subcell (a = 5.4939(4) A, b = 16.6896(9) A, c = 3.8728(2) A at 4.9 GPa). The OI phase transforms to an orthorhombic phase OII at around 7 GPa. The OII phase is characterized by a superstructure √2ap × 3√2ap × 2ap (a = 5.5021(3) A, b = 16.2439(11) A, c = 7.6960(4) A at 9.7 GPa). During decompression, significant hysteretic behavior was found. The OII phase was stable down to about 3 GPa. The OII phase then transforms to an orthorhombic phase OIII that is characterized by a superstructure √2ap × 2√2ap × 2ap (a = 5.5617(6) A, b = 11.215...

These systems may have wide technological applicationsbecause they allow control of electric properties by magneticfield and control of magnetic properties by electric field.Applications might include multiple-state memory elementsand will allow exploitation of the advantages of both ferro-electric and magnetic random-access memories.

A new compound, Bi3Mn3O11, with a KSbO3-type structure was prepared using a high-pressure technique. Its structural, chemical, and magnetic properties have been investigated. Bi3Mn3O11 was shown to be a ferrimagnet with rather high TC despite the random distribution of manganese ions with different oxidation states in one site. Bi3Mn3O11 gradually loses oxygen on heating forming several phases with the same structure but with different magnetic properties. These findings may revive interest in the KSbO3 family of compounds, which is rather adaptive considering the cation variations and oxygen content.

The Na-based osmium oxide pyrochlore was synthesized for the first time by an ion-exchange method using KOs{sub 2}O{sub 6} as a host. The composition was identified as Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O by electron probe micro-analysis, thermogravimetric analysis, and structural analysis using synchrotron X-ray diffraction. Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O crystallizes in a regular pyrochlore structure with some defects (space group: Fd-3m, a=10.16851(1) A). Electrical resistivity, heat capacity, and magnetization measurements clearly showed absence of superconductivity down to 2 K, being in large contrast to what was found for the beta-type pyrochlore superconductor AOs{sub 2}O{sub 6} (A=Cs, Rb, and K). The Sommerfeld coefficient is 22 mJ K{sup -2} mol{sup -1}, being the smallest among AOs{sub 2}O{sub 6}. A magnetic anomaly at {approx}57 K and associated magneto-resistance (+3.7% at 2 K in 70 kOe) were found. - Graphical abstract: Crystal structure of the Na-based Os oxide pyrochlore Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O.

High-pressure structural properties of perovskite-type BiMnO3 have been investigated by synchrotron X-ray powder diffraction at room temperature. A new monoclinic phase having P21/c symmetry was found between about 1.5 and 5.5 GPa. Above 8 GPa, the orthorhombic GdFeO3-type phase (space group Pnma) is stable. The crystal structure of BiMnO3 at 8.6 GPa and room temperature was investigated (a = 5.5132(3) A, b = 7.5752(3) A, c = 5.4535(3) A). The orthorhombic phase of BiMnO3 has an orbital order similar to LaMnO3 but with a different arrangement of orbitals in the ac plane. High-pressure room-temperature behavior of BiMnO3 differs from high-temperature behavior at ambient pressure in comparison with BiCrO3 and BiScO3. These findings may open new directions in investigation of BiMnO3.

The crystal and magnetic structures of SrFe 2+ 2 (PO 4 ) 2 have been determined by neutron powder diffraction data at low temperatures (space group P 2 1 / c (no. 14); Z =4; a =9.35417(13) A, b =6.83808(10) A, c =10.51899(15) A, and β =109.5147(7)° at 15 K). Two magnetic phase transitions were found at T 1 =7.4 K (first-order phase transition) and T 2 =11.4 K (second-order phase transition). The transition at T 2 was hardly detectable by dc and ac magnetization measurements, and a small anomaly was observed by specific heat measurements. At T 1 , strong anomalies were found by dc and ac magnetization and specific heat. The structure of SrFe 2 (PO 4 ) 2 consists of linear four-spin cluster units, Fe2–Fe1–Fe1–Fe2. Below T 1 , the propagation vector of the magnetic structure is k =[0,0,0]. The magnetic moments of the inner Fe1–Fe1 atoms of the four-spin cluster unit are ferromagnetically coupled. The magnetic moment of the outer Fe2 atom is also ferromagnetically coupled with that of the Fe1 atom but with spin canting. The four-spin cluster units form ferromagnetic layers parallel to the [−101] plane, while these layers are stacked antiferromagnetically in the [−101] direction. Spin canting of the outer Fe2 atoms provides a weak ferromagnetic moment of about 1 μ B along the b -axis. The refined magnetic moments at 3.5 K are 4.09 μ B for Fe1 and 4.07 μ B for Fe2. Between T 1 and T 2 , a few weak magnetic reflections were observed probably due to incommensurate magnetic order.

Ferroelectric materials, which have a reversible spontaneous polarization and generate an electric potential when subjected to a mechanical stress (piezoelectricity), have applications in nonvolati...

The crystal structure of a new high-pressure modification of cadmium divanadium hexa­oxide, CdV2O6, was refined from X-ray single-crystal data. It contains zigzag chains of edge-sharing VO6 octa­hedra. Octa­hedra in adjacent chains share corners and form corrugated layers. Octa­hedrally coordinated Cd atoms, which lie on twofold axes, are situated between the layers. The columbite-like structure results in a strong distortion of the CdO6 octa­hedra which may be stabilized only at high pressure.

Solid solutions BiMn1-xScxO3 (0 ≤ x ≤ 1) were prepared at 6 GPa and 1383−1443 K. Selected area and convergent beam electron diffraction showed that BiMn0.9Sc0.1O3 crystallizes in the centrosymmetric space group C2/c at room temperature. The structure parameters of BiMn0.9Sc0.1O3 were refined by the Rietveld method from laboratory X-ray diffraction data (Z = 8; a = 9.6029(3) A, b = 5.60988(14) A, c = 9.7690(3) A, β = 108.775(2°) at 293 K). The Mn−O bond lengths suggest that the orbital order present in BiMnO3 at 300 K disappears in BiMn0.9Sc0.1O3. Therefore, the monoclinic-to-monoclinic phase transition observed in BiMnO3 at 474 K and associated with the orbital melting was not detected in BiMn1-xScxO3 for x ≥ 0.05 down to 133 K. BiMn1-xScxO3 were characterized by dc and ac magnetization, specific heat, and differential scanning calorimetry measurements. The long-range ferromagnetic order seems to survive for x = 0−0.2. For x ≥ 0.4, the samples showed spin-glass-like features. The Weiss temperature deduced...

Solid solutions of Sr9+xCo1.5−x(PO4)7 were found in the compositional range of 0.05 ⩽ x ⩽ 0.30 . The structure of Sr9.2Co1.3(PO4)7 ( x = 0.2 ) was determined from single crystal X-ray diffraction (space group R 3 ¯ m (No. 166); Z = 3 ; a = 10.6100 ( 5 ) A and c = 19.6960 ( 5 ) A ; V = 1920.17 ( 14 ) A 3 ; ρ cal = 4.014 g cm - 3 ; μ = 20.377 mm - 1 ) and refined to R 1 = 0.0343 and w R 2 = 0.0633 for 586 reflections with I > 2 σ ( I ) . Sr9.2Co1.3(PO4)7 is structurally related to β-Ca3(PO4)2 and Sr3(PO4)2 and has disordered arrangements of some Sr2+, Co2+, and PO43− ions. Sr2+ ions at a 9e site are statistically disordered among four positions near the center of symmetry. Co2+ and Sr2+ ions are split along the c-axis to occupy a 6c site that is 75% vacant. The P1O4 tetrahedra are orientationally disordered. Sr2+ ions at an 8-fold coordinated 18h site, Co2+ ions at an octahedral 3a site, and the P2O4 tetrahedra are ordered in the structure of Sr9.2Co1.3(PO4)7. Features of Raman spectra are discussed in relation to the crystallographic structure of Sr9.2Co1.3(PO4)7 and in comparison with Raman spectra of β-Ca3(PO4)2-type and Sr3(PO4)2-type compounds. Sr9.2Co1.3(PO4)7 is paramagnetic between 2 and 300 K with an effective magnetic moment of 4.98μB per Co2+ ion.

New oxides, BiAlO3 and BiGaO3, were prepared using a high-pressure high-temperature technique at 6 GPa and 1273−1473 K. BiAlO3 is isotypic with multiferroic perovskite-like BiFeO3 and has octahedrally coordinated Al3+ ions. Structure parameters of BiAlO3 were refined from laboratory X-ray powder diffraction data (space group R3c; Z = 6; a = 5.37546(5) A and c = 13.3933(1) A). BiGaO3 has the structure closely related to pyroxene-like KVO3. Structure parameters of BiGaO3 were refined from time-of-flight neutron powder diffraction data (space group Pcca; Z = 4; a = 5.4162(2) A, b = 5.1335(3) A, and c = 9.9369(5) A). The GaO4 tetrahedra in BiGaO3 are joined by corners forming infinite (GaO3)3- chains along the a axis. Bi3+ ions in BiGaO3 have 6-fold coordination. Both BiAlO3 and BiGaO3 decompose at ambient pressure on heating above 820 K to give Bi2M4O9 and Bi25MO39 (M = Al and Ga). Vibrational properties of BiAlO3 and BiGaO3 were studied by Raman spectroscopy. In solid solutions of BiAl1-xGaxO3, a C-centered...

Physical and chemical properties of Sr9Fe(PO4)7 and Sr9FeD(PO4)7 were investigated by Mossbauer, infrared, and Raman spectroscopy, magnetization and dielectric measurements, differential scanning calorimetry, and thermal analysis. Sr9Fe(PO4)7 undergoes an antiferroelectric-paraelectric (AFE-PE) phase transition at Tc = 740 K. Structure parameters of the AFE phase at 293 K were refined from time-of-flight (TOF) neutron powder diffraction data (space group C2/c; Z = 4; a = 14.4971(2) A, b = 10.6005(13) A, c = 17.9632(3) A, and β = 112.5053(9)°), and those of the PE phase at 923 K from synchrotron X-ray powder diffraction data (space group R3m; Z = 3; a = 10.70473(13) A and c = 19.8605(2) A). Parts of Sr atoms and PO4 tetrahedra are highly disordered in the PE phase. Sr9FeD(PO4)7 was prepared by treating Sr9Fe(PO4)7 with D2 at 820 K. The incorporation of D atoms above Tc kept the structure of the high-temperature modification of Sr9Fe(PO4)7. Therefore, Sr9FeD(PO4)7 is isotypic with the PE phase of Sr9Fe(PO4...