Magnetic Structure of Inorganic–Organic Hybrid (C6H5CH2CH2NH3)2MnCl4 Using Magnetic Space Group Concept

Previously, we reported that inorganic–organic hybrid (C6H5CH2CH2NH3)2MnCl4 (Mn-PEA) is antiferromagnetic below 44 K by using magnetic susceptibility and neutron diffraction measurements. Generally, when an antiferromagnetic system is investigated by the neutron diffraction method, half-integer forbidden peaks, which indicate an enlargement of the magnetic cell compared to the chemical cell, should be present. However, in the case of the title compound, integer forbidden peaks are observed, suggesting that the size of the magnetic cell is the same as that of the chemical cell. This phenomenon was until now only theoretically predicted. During our former study, using an irreducible representation method, we suggested that four spin arrangements could be possible candidates and a magnetic cell and chemical cell should coincide. Recently, a magnetic structure analysis employing a magnetic space group has been developed. To confirm our former result by the representation method, in this work we employed a magnetic space group concept, and from this analysis, we show that the magnetic cell must coincide with the nuclear cell because only the Black–White 1 group (equi-translation or same translation group) is possible.

Neutron diffraction study of the crystal structure of TlInSe2 at high pressure

We have investigated the crystal structure of strongly anisotropic semiconductor TlInSe2 by neutron diffraction method under high pressure upto P = 3.3 GPa. It was shown that the tetragonal phase of TlInSe2 crystal (the space group I4/mcm) is stable in the whole investigated range of pressure. The lattice parameters dependence of the pressure and the unit cell volume are obtained, the linear coefficients of compressibility and the bulk moduli are calculated. At the low pressure, obtained value of compressibility for the lattice parameter a is k[Formula: see text] = 14.23 × 10[Formula: see text] GPa[Formula: see text] and for c is k[Formula: see text] = 5.93 × 10[Formula: see text] GPa[Formula: see text]. Obtained values for bulk modulus B0 and its pressure derivative B[Formula: see text] in tetragonal phase are 30(7) GPa and 4(1), respectively.

Nanocrystalline Features of Structure and Luminescent Properties of (Y1−xLax)3(Al1−yGay)5O12:Ce3+ Garnets

The compounds of (Y[Formula: see text]Lax)3(Al[Formula: see text]Gay)5O[Formula: see text]:Ce[Formula: see text] compositions with partial substitution of Y[Formula: see text] and Al[Formula: see text] by La[Formula: see text] and Ga[Formula: see text], respectively, were fabricated by the co-precipitation method using different precipitants. Detailed investigations of the crystalline structure were made using the neutron diffraction method. The influence of the precipitant, quantity and type of the substituted ions on the structural and luminescent properties of the compounds was established. Distortion of the oxygen dodecahedron in the crystals has the strongest impact on their luminescent properties.

Hydrogen Distribution in Partly Desorbed MgH2 Samples

The structure of MgH2 samples has been investigated by the neutron diffraction method at room temperature and 5 K. Samples of MgH2 have been prepared with vacuum extraction technique at high temperature. Obtained neutron data demonstrated that samples contain coexisting Mg and MgH2 phases in different rate. The distribution of hydrogen atoms in the structure of the samples is comparable at both temperatures. Collected neutron data and results of X-ray analysis show that microstructure of the samples is different at room and at low temperature. Non-stability of partly desorbed MgH2 samples after low temperature treatment has been discussed on basis of different diffusion of hydrogen atoms in varied microstructure.