类镓等电子序列ZrX—RhXV离子的4s^24p—4s^24d,4s^24p—4s4p^2,4s^24 …

本文对类镓等电子序列ＧａＩ－ＸｅＸＸＩＶ离子４ｓ＾２４ｐ、４ｓ＾２４ｐ、４ｓ＾２４ｄ、４ｓ４ｐ＾２、４ｐ＾３和４ｓ＾２５ｓ组态组级结果和组态相互作用了理论分析，找出沿等电子序列的变化规律。     

Electronic structure of (LaSr)2CuO4 and (NdCe)2CuO4

The electronic structure of (LaSr)₂CuO₄ and (NdCe)₂CuO₄ are compared. It is concluded that in both materials after doping by holes and electrons respectively the Fermi energy is at the top of the valence band. This explains many symmetrical properties and in particular the photoemission experiments.Dedicated to Prof. P. Kienle on the occasion of his 60th birthday     

(4×2) and (2×4) reconstructions of GaAs and InP(001) surfaces

Received: 21 March 1997/Accepted: 12 August 1997     

Optical studies of the ferroelastic phase transitions in Rb3H(SeO4)2, (NH4)3H(SO4)2 and (NH4)3H(SeO4)2

Optical observations of growth twins and ferroelastic domains and measurements of the rotation of the optical indicatrix were carried out for Rb₃H(SeO₄)₂ and (NH₄)₃H(SO₄)₂ using an optical microscope. Taking into account the symmetry reduction from the rhombohedral (Rm) to the monoclinic phase (B2/a) the occurrence of domains and growth twins can be well described. The orientations of oblique ferroelastic walls are well determined by the spontaneous strains ^s e ₁₁ and ^s e ₂₃ at room temperature.     

Simulation of the NaGd(MoO4)2–NaEu(MoO4)2 and Na2Gd4(MoO4)7–Na2Eu4(MoO4)7 Solid Solutions by the Interatomic Potential Method

Physics of the Solid State - Simulation of the solid solutions in the system of double sodium–gadolinium and sodium–europium molybdates, which are promising matrices for solid state...     

Proton ENDOR of VO(H2O)5 2+ in Mg(NH4)2(SO4)2)26H2O

ENDOR measurements at 25 K have been used to determine the hyperfine coupling tensors for all ten protons in the VO(H₂O)₅ ²⁺ ion in single crystals of Mg(NH₄)₂(SO₄)₂6H₂O. The traceless components of all the tensors are close to axial and their use in a point dipole treatment enables a very plausible geometrical model of the complex ion to be constructed. Six of the protons in the equatorial water molecules have substantial positive isotropic couplings and it is suggested that these reflect the direct admixture of hydrogen 1s components into the singly occupied orbital.     

Proton magnetic relaxation in (TMA)2HgBr4 and (TMA)2HgI4

Internal motions of the protonic groups have been studied in polycrystalline [(CH₃)₄N]₂HgBr₄ and [(CH₃)₄N]₂HgI₄ from the temperature dependence of proton spin relaxation time (T ₁) and the data analysed according to the spin lattice relaxation model due to Albert and coworkers. The temperature dependence ofT ₁ in the above compounds is compared with that in (TMA)₂HgCl₄ and (TMA)₂ZnCl₄.     

有机材料(EDT-DSDTFVO)FeCl_4和(EDT-DSDTFVO)GaCl_4的输送现象

通过对有机材料(EDT-DSDTFVO)2FeCl4和(EDT-DSDTFVO)2GaCl4的输送测定,对其电阻率的温度依赖性以及压力效果进行了系统的比较,虽然两类盐的电阻率随着温度的变化行为十分相似,但是其压力效果尤其在高压时表现出明显的差异性。认为这种差异性和π-d相互作用密切相关。在这里,用EDT-DSDTFVO表示ethylenedithiodiselenadithiafulvalenothioquinone-1,3-dithiole methide。     

Study of Phase Transformations in (Cs,NH4)4(HSO4)3(H2PO4) Crystals

Physics of the Solid State - Phase transitions in crystals of (Cs,NH4)4(HSO4)3(H2PO4) solid solutions have been investigated by synchronous thermal analysis and polarization microscopy at different...     

The Mössbauer spectrum of synthetic hureaulite: Fe5 2+(H2O)4(PO4H)2(PO4)2

The crystal structure of synthetic ferrous hureaulite, Fe₅ ²⁺ (H₂O)₄(PO₄H)₂(PO₄)₂, was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å, β=96.27(3)°, V=1463.6(6) Å³, Z=4 and D _calc=3.327 g/cm³. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO₄)³⁺ and acid (PO₄H)²⁺ tetradentate groups. These are centered on Fe²⁺ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe²⁺ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mössbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites.     

Investigation into phase diagrams of the fluorine-oxygen system: Ferroelastic-antiferroelectric (NH4)2WO2F4-(NH4)2MoO2F4

Thermal, physical, structural, optical, and dielectric investigations have been performed for oxyfluoride solid solutions (NH₄)₂W_{1 — x} Mo _x O₂F₄ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1). The character of the influence of the chemical and hydrostatic pressures on the stability of the parent (space group Cmcm) and distorted ferroelastic and antiferroelectric phases has been determined by analyzing the temperature-pressure, unit cell volume-composition, and temperature-composition phase diagrams. The specific features of the nature and mechanism of the phase transitions have been discussed using the available data on the structural, entropy, and dielectric parameters.     

Orbital order in ZnV(2)O(4)

In view of recent controversy regarding the orbital order in the frustrated spinel ZnV(2)O(4), we analyze the orbital and magnetic ground state of this system within an ab initio density functional theory approach. While local density approximation+Hubbard U calculations in the presence of a cooperative Jahn-Teller distortion stabilize an A-type staggered orbital order, the consideration of relativistic spin-orbit (SO) effects unquenches the orbital moment and leads to a uniform orbital order with a net magnetic moment close to the experimental one. Our results show that ab initio calculations are able to resolve the existing discrepancies in previous theories and that it is the SO coupling along with electronic correlations which play a significant role in determining the orbital structure in these materials.     

Anomalous Spin-Flop in Antiferromagnetic Cu(pz)2(ClO4)2

Journal of Experimental and Theoretical Physics - An explanation is proposed for the anomalous spin-flop in antiferromagnetic Cu(pz)2(ClO4)2. Due to the closeness of the monoclinic and tetrahedral...     

Superprotonic conductivity in Cs5(HSO4)2(H2PO4)3 single crystal

The conductivity of cesium hydrosulfate-phosphate single crystals obtained for the first time has been studied. It has been shown that these single crystals undergo a phase transition to a state with superprotonic conductivity. It has been found that the state with high proton conductivity is retained during thermal cycling for a long time and has a quasi-reversible nature.     

Photoluminescence properties of Ca_4La_6(SiO_4)_4(PO_4)_2O_2-based phosphors for wLEDs

The apatite compound Ca_4La_6(SiO_4)_4(PO_4)_2O_2(CLSPO) was explored as the host material for phosphors used in white light-emitting diodes(w LEDs). The crystal structure of the CLSPO host prepared by the solid-state reaction method was investigated with Rietveld refinement. The rare earth ions(Eu~(3+)/Tb~(3+)/Ce~(3+), Tb~(3+)/Tb~(3+), Mn~(2+))activated CLSPO phosphors were synthesized, and their photoluminescence properties, quantum yields, as well as thermal stabilities, were studied. Under near-ultraviolet excitations, the Eu~(3+) and Tb~(3+) -doped CLSPO compounds exhibited red and green emissions with high luminescence efficiencies. Besides, tunable emissions from green to orange were obtained by introducing Mn~(2+) ions into the Tb~(3+) -doped CLSPO samples. The results showed that the phosphors studied may have potential applications for w LEDs.     

Phase transitions in oxyfluoride (NH4)2WO2F4

(NH₄)₂WO₂F₄ single crystals are grown, and their polarization-optical, calorimetric, and birefringence properties are studied in the temperature range 90–350 K. A first-order structural phase transition is found to occur at T ₀₁↑ = 202 K with thermal hysteresis of ΔT ₀₁ ≈ 6–12 K. The phase transition is accompanied by twinning and modification of the symmetry . An additional weak anomaly in the differential scanning calorimeter signal is found at T ₀₂ ≈ 170 K. The total thermal effect of both anomalies is ∑ΔH _i = 3200 ± 400 J/mol and ∑ΔS _i = 16.5 ± 2.0 J/mol K. The phase transition at T ₀₁ is of the order-disorder type.