V. N. Molchanov's research while affiliated with Russian Academy of Sciences and other places

... It is the most common structural unit found in BaF 2 -REF 3 fluorite and fluorite related phases [16]. Nevertheless, in fluorite type BaF 2 -REF 3 (RE=Yb-Lu) phases new type of structural unit RE 8 Ba 6 F 71 (octahedral alkali earth supercluster) was recently discovered [40]. Indeed, two distinct Er 3+ sites were also found in the rhombohedral Ba 4 Yb 3 F 17 [27]. ...

... A range of the intersite CDW potential that reaches out in real space is within two lattice constants of 6~10 Å when the lattice constant in a metal is considered 4 ± 1 Å. Experimental evidence of the CDW in oxide superconductors is a distortion of octahedral structure observed just below T c 45,46 and discontinuity 27 of the bulk modulus at T c . For superconductivity, when the CDW potential is introduced, the on-site critical Coulomb energy U c in the BR picture should be present at the bipolaron, then, as a nonlocal potential, V e-ph = V CDW + U c < 0 is considered a constant, because V CDW and U c are determined as fixed values in a crystal. ...

... The thermal conductivity of a fused and, even more so, ceramic sample, can differ from the thermal conductivity of a single crystal by dozens and hundreds of times. So, the thermal conductivity can be decreased due to the thermal resistance of the boundaries between grains in an alloy and also due to a porous ceramic structure [7,8]. Thus, a very topical problem is the development of a reliable method of estimating the thermal conductivity of a material from the experimental data on their characteristics, the values of which are independent of whether a single-crystal or polycrystalline sample is used in the experiment. ...

... The reason for this behavior remains unclear a is apparently related to the thermodynamic instability of BaF2-based solid solutions at l temperatures. Many studies have been devoted to the investigations of the defect structure in c centrated solid solutions formed upon the incorporation of rare-earth fluorides of the rium group into barium fluoride [44][45][46][47]. There is no unambiguous interpretation of th from the point of view of the cluster structure of defects. ...

... LGS and its isomorphs exhibit quality and electromechanical coupling factors which are, respectively, four [2] and two times [3] greater than those of quartz. One of the most important features of LGX is its phase transition, which occurs under high temperature at its melting temperature of 1473°C and under high pressure at 10 GPa [4]. These excellent properties of LGS and its isomorphs provide promising applications for sensors and timing applications in the oil and gas industry for high-temperature and high-pressure (HTHP) applications. ...

... Stibiotantalite is isostructural with other ABO 4 typestructure series minerals (Keller 1962, Zubkova et al. 2002. Their crystal structures typically consist of chains of edge-sharing AO 6 octahedra parallel to the a axis, and BO 6 octahedral sheets are combined with AO 6 along with the c axis (Kazantsev et al. 2002, Zubkova et al. 2002. They are also characterized by the presence of cations with lone-pair electrons (Sb 3þ , Bi 3þ ) (Thornton 1977, Amador et al. 1988, which cause distortion in B 3þ O 6 octahedra. ...

... The anion core of the clusters consists of interstitial anions. According to the principle of local charge compensation, the impurity cations R 3+ are located around the anion core to form cation-anion clusters [2][3][4][5]. The presence of vacancies in the main anionic motif and interstitial anions in one or more positions is considered to be evidence of cluster formation in the disordered M 1−x R x F 2+x phases. ...

... Due to the fact that the electroneutrality condition for the refined composition is not satisfied, we assumed that a certain number of Ca 2+ ions in the structure are interstitial ones, as for the (La 2.964 ◻ 0.036 )La i(0.036) Zr 0.5 Ga 5 Si 0.5 O 14 [26]. The analysis of the residual nuclear density does not exclude such possibility. ...

... However, the use of these compounds depends on the composition (in other words, on the type and concentration of point defects), which does not coincide with the composition of the initial charge. There are quite a few works devoted to the structural investigation of CNGS [6,8,11] and LGN [6,17,18] crystals. All of them were performed using X-ray, and the occupancies were refined only in some cases. ...

... In both compounds, the absence of X-ray scattering contrast between Ga 3+ /Ge 4+ and Zn 2+ /Ge 4+ means that the distribution of these cations over the three framework sites (B, C, and D) cannot be obtained directly by conventional (non-anomalous) X-ray diffraction methods, and instead indirect routes (e.g., analysis based on refined bond distances) have been used to deduce the nature and extent of cation ordering. 17 Such isoelectronic pairs can be distinguished directly by neutron d i ff r a c t i o n ( N P D ) , a s d e m o n s t r a t e d f o r La 3 Ga 5−x Ge 1+x O 14+x/2 , 13 but NPD alone cannot be used for direct analysis of more complex systems with three or more isoelectronic cations distributed over the framework sites B, C, and D. Atomic-resolution STEM-EDS mapping offers a solution to this problem by detecting each element type directly with a spatial resolution of around 2−3 Å. While this technique is most often used qualitatively, intensities of atomic columns can be extracted by Gaussian curve fitting which is most often applied to 1D line profiles to provide quantitative information about atomic site occupancies. ...