Linear Structural Trends and Multi-Phase Intergrowths in Helvine-Group Minerals, (Zn,Fe,Mn)8[Be6Si6O24]S2

Synchrotron high-resolution powder X-ray diffraction (HRPXRD) and Rietveld structure refinements were used to examine the crystal structure of single phases and intergrowths (either two or three phases) in 13 samples of the helvine-group minerals, (Zn,Fe,Mn)8[Be6Si6O24]S2. The helvine structure was refined in the cubic space group P4¯3n. For the intergrowths, simultaneous refinements were carried out for each phase. The structural parameters for each phase in an intergrowth are only slightly different from each other. Each phase in an intergrowth has well-defined unit-cell and structural parameters that are significantly different from the three endmembers and these do not represent exsolution or immiscibility gaps in the ternary solid-solution series. The reason for the intergrowths in the helvine-group minerals is not clear considering the similar radii, identical charge, and diffusion among the interstitial M cations (Zn2+, Fe2+, and Mn2+) that are characteristic of elongated tetrahedral coordination. The difference between the radii of Zn2+ and Mn2+ cations is 10%. Depending on the availability of the M cations, intergrowths may occur as the temperature, pressure, fugacity fS2, and fluid composition change on crystallization. The Be–Si atoms are fully ordered. The Be–O and Si–O distances are nearly constant. Several structural parameters (Be–O–Si bridging angle, M–O, M–S, average <M–O/S>[4] distances, and TO4 rotational angles) vary linearly with the a unit-cell parameter across the series because of the size of the M cation.

The Enhancement of Energy Storage Performances via Combining Relaxor Behaviors With the Crucial Point of Solubility Limit

(1-x)(0.96Na0.5Bi0.5TiO3-0.04BiMnO3)-xLaMnO3 ternary solid solution films were fabricated by Sol-gel methods. It takes advantage of the large polarization from 0.96NBT-0.04BMO limit solid solution at crucial point of solubility limit to enhance energy density. And LaMnO3 was introduced to improve the energy storage efficiency via the enhancement of relaxor behaviors. It is shown that the relaxor behaviors had been enhanced, and a large energy storage density of 87.9 J/cm3 and efficiency of 56.5 % were achieved for 0.85(NBT-BMO)-0.15LM films, with increase ratio of 4.9 % and 13.3 % respectively than 0.96NBT-0.04BMO solubility limit films. However, when LaMnO3 is beyond a certain limit, the breakdown strength is reduced due the formation of the current channel. Thus it suggests a alternative method that combining relaxor behaviors with solubility limit films, which provides a way to regulate the energy storage performances for film capacitors.

Подавление температурной зависимости длины волны излучения в светодиодных структурах со ступенчатым гетеропереходом II типа InAsSb/InAsSbP

The results of a study of the electroluminescence of the asymmetric InAs/InAs1−ySby/InAsSbP LED heterostructures with a molar fraction of InSb in the ternary solid solution in the active region y=0.15 and y=0.16 in the temperature range 4.2−300 K are presented. Based on the experimental data, the formation of a staggered type II heterojunction at the InAs1−ySby/InAsSbP heterointerface was determined. The dominant contribution of the interface radiative transitions at the type II heterointerface in the temperature range 4.2−180 K was shown, which makes it possible to minimize the temperature dependence of the operating wavelength of the LEDs.

The Phase Relations of the Co-Ni-In Ternary System at 673 K and 873 K and Magnetic Properties of Their Compounds

The phase relationships of the ternary Co-Ni-In system at 673 K and 873 K were investigated by means of powder X-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, and optical microscopy. Though CoIn2 does not exist at 873 K, the ternary solid solution Co1−xNixIn2 exists at both 673 K and 873 K with different composition ranges. The Rietveld refinements were carried out to investigate the crystal structure of Co1−xNixIn2 (x = 0.540, and 0.580) and Ni2−xCoxIn3 (x = 0.200). The magnetization dependence of temperature (MT) curves of Ni2−xCoxIn3 (x = 0.200) and Co1−xNixIn2 (x = 0.540) are similar to those of the ferromagnetic shape memory alloys Ni-Mn-A (A = Ga, Sn, and In), but do not undergo martensitic transformation. The maximum magnetic entropy changes in Ni2−xCoxIn3 (x = 0.200) and Co1−xNixIn2 (x = 0.540) under 3T are 1.25 and 1.475 J kg−1K−1, respectively.