G. Batdemberel

Hydrogen uptake in Mg thin film alloys

The work is focused on the study of the possibility to reduce the binding energy of hydride formation by alloying metal magnesium with palladium and chromium. Hydrogen uptake in Mg-Pd and Mg-Cr films was investigated by in-situ resistance measurements. Experimental data were used to calculate the dependence of the p-ΔR-T and isotherms showing the enthalpy and entropy change were drawn. The data were then compared with bulk values for MgH2 and MgPd0.6. As a result, the conclusion is made that the enthalpy change or binding energy was reduced from -0.77 eV/H2 down to -0.65 ÷-0.5 eV/H2.

A study of stability and magnetic phase separation of Li x FePO 4 by density functional approach

We present the results of density functional calculations to understand the stability and magnetic phase separation of LiFePO4. The most stable ground state of the LixFePO4 compound is investigated using the first-principles and molecular dynamics (MD) methods within the framework of density functional approach.

Hydrogen storage in carbon based nanoclusters

We have studied the hydrogenation of small, medium sized carbon based nanoclusters. Density functional theory was used to calculate the energy and atomic forces. The average hydrogen binding energy for a hydrogen binding as an atom is calculated for all clusters.

Nanocrystalline ZnO powder prepared by high energy ball mill

We have obtained zinc oxide (ZnO) in the form of nanocrystallites with crystallite sizes from 46 nm to 3 nm by milling 1.4 micron ZnO powders in the high energy ball mill (HEBM) for the different times: 1, 5 and 8 hours. Crystal structure changes of the ZnO nanocrystallites were studied by x-ray diffraction techniquies. It was established appearance of two new phases: pure zinc (Zn) and cubic zinc oxide (ZnO) among the initial hexagonal zinc oxide phase. From the x-ray patterns by using Scherrer equation have been determined nanocrystallite sizes of samples with the different milling times. Also, by using PCCS with Nanophox we have found particle diameters, their distributions and specific surface area values for each sample. By using Rietveld method are calculated crystal lattice parameters of the hexagonal ZnO, the main phase.

A study of nanoparticles in Ulaanbaatar soil

Soils contain many kinds of inorganic and organic particles, nanoparticles. In addition, natural nanoparticles could strongly influence on solubility, transport, degradation and bioavailability of environmental pollution. The present article deals with the extraction and characterization of nanoparticles in soil. Nanoparticles were extracted from 5 soil samples in different regions of Ulaanbaatar city. The suspension of soil was prepared by a sonication and centrifugal method. Size distribution of nanoparticles was measured by using the Photon Cross Correlation Spectroscopy (PCCS). The results showed that, size distriburion interval of soil samples are 319-708 nm, 343-659 nm, 276-659 nm, 570-1094 nm and 319-612 nm respectively. On the other hand, there is not determined ultrafine nanoparticles. This result demonstrates that soil contamination and degradation of Ulaanbaatar city could be less.

A study of nanoparticle sizes and their distributions aerosols along the road in Ulaanbaatar city

Particle sizes and their distributions of aerosols along the road in Ulaanbaatar city were studied by Photon Cross Correlation Spectroscopy (PCCS) NANOPHOX (Sympatec GmbH, Germany). Mean diameter (x₀), size distribution range, specific surface area (Sv) of aerosol particles are equal to 1.1÷2.5μm, 74nm÷4.0μm and 2.38÷5.43m²/cm³ respectively. On the other hand, particles distribution is Gaussian with density 0.02÷8.15 (q₃lg) in the range of 790nm÷3.8μm. However, nanoparticles with diameters less than 74nm were not observed. The results reveal that samples contain 0.02% (volume persent) ultrafine particles or nanoparticles occur in the range of 74-100nm, 83.73% fine particles (PM2.5) occur in the range of 100nm÷2.4μm and 16.25% coarse particles (PM10) occur in the range of 2.4-4.0μm. It can be concluded that road aerosol sample contain high percent of PM2.5 particles.

A study of crystal structure and particle size of perovskite type La 1−x Cu x MnO 3+δ (x≤0.1) compounds suspended in water

Nanosized La_1-xCu_xMnO₃ (x≤0.1) was synthesized at different temperatures by using heteronuclear complexing method. X-ray diffraction analysis show that sample consists of two phases: La_1-xCu_xMnO₃ (x≤0.1) having R3̅c space group with rhombohedral symmetrical structure and La₂Cu₂O₅ having C2/c space group with monoclinic symmetrical structure. The results show the quantity of La_1-xCu_xMnO₃ increase from 91.22 to 97.62%, while quantity of La₂Cu₂O₅ compound decrease from 8.78 to 2.37% with rising of calcination temperature from 500°C to 900°C. The Photon Cross Correlation Spectroscopy (PCCS) was used to measure size distribution. The results reveal that particle mean diameter increases from (276±4) to (455±5)nm, particle specific surface area (Sv) decreases from 21.84 to 13.29 m²/cm³, particle size distribution equals to 55-761nm and particle surface and volume mean diameter (SMD, VMD) increase from 247 to 459nm.

TOF neutron scattering investigations of crystal structures in K 1−x (NH 4 ) x Cl (x=0.2, 0.8) mixed crystals

TOF neutron diffraction study shows that at the room temperature K<inf>0.2</inf>(NH<inf>4</inf>)<inf>0.8</inf>Cl and K<inf>0.8</inf>(NH<inf>4</inf>)<inf>0.2</inf>Cl compounds form cubic crystal lattices with the corresponding space groups: Fm3m and Pm3m. It was established considerable distortion of hydrogen atoms in these structures from their initial positions 8g.

X-ray diffraction studies of crystal structures and phase transitions in K 1−x (NH4) x Cl mixed salts

Crystal structures and phase transitions of K<inf>1−x</inf> (NH<inf>4</inf>)<inf>x</inf>Cl mixed salts with non-stoichiometric composition x=0.1, 0.2, 0.5, 0.6 and 0.8 have been studied by x-ray diffraction technique. It was established that at the room temperature K<inf>0.8</inf>(NH<inf>4</inf>)<inf>0.2</inf>Cl and K<inf>0.9</inf>(NH<inf>4</inf>)<inf>0.1</inf>Cl compounds have Fm3̅m symmetry and K<inf>0.2</inf>(NH<inf>4</inf>)<inf>0.8</inf>Cl compound has Pm3m, when K<inf>0.5</inf>(NH<inf>4</inf>)<inf>0.5</inf>Cl and K<inf>0.4</inf>(NH<inf>4</inf>)<inf>0.6</inf>Cl compounds consist of two phases with space groups Fm3̅m + Pm3m. Lattice parameters, positions and thermal factors of K, N and CI atoms have been refined using x-ray diffraction study for each mixed crystals.

Crystal structural investigations of Mongolian natural zeolites

We have studied zeolitic rocks discovered in Mongolia using electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD) methods. SEM, XRF and XRD measurements were carried out in the Max Plank Institute of Stuttgart, Germany. Our samples are collected from Mongolian deposits: Tsagaan tsav, Tushig uul, Urgun deposit, Bayan Zurkh Black Mountain and Mandal ovoo. Firstly, we have made chemical element analysis by using X-ray fluorescence spectroscopy which gives chemical contents of samples from all zeolite deposits. Comparing contents of above 5 deposits samples shows us that zeolite of Tushig Mountain, Dornogobi, is has the highest content of potassium and can be identified in potassium clinoptilolite- K (2.56 at %), others belong to clinoptilolite- Na. The main cations are K,Na,Ca,Mg,Fe,Ti for all the samples from the above mentioned deposits. Also, the (Si Al)/O ratio shows that the Mongolian zeolites have comparatively good qualities. We made X-ray phase analysis study on X-ray powder diffractometer Bruker-Axes D8 and refined the X-ray diffraction spectra by using ≪Match! Crystal Impact≫ program. As a result, we established that these zeolites are Na and K type of clinoptilolite with monoclinic symmetry (C2/m). Finally, the exact crystallochemical formula of clinoptilolites can be written as the next: • (Na<inf>2.02</inf>, K<inf>1.81</inf>, Mg<inf>0.49</inf>, Ca<inf>0.46</inf>, Fe<inf>0.36</inf>)(Al<inf>6.28</inf>O<inf>30.45</inf>) (Si<inf>28.47</inf>O<inf>30.45</inf>)·z·H<inf>2</inf>O for Tsagaan tsav sample. • (K<inf>2.56</inf>, Na<inf>1.69</inf>, Mg<inf>0.64</inf>, Ca<inf>0.47</inf>, Fe<inf>0.78</inf>)(Al<inf>6.39</inf>O<inf>28.15</inf>) (Si<inf>31.17</inf>O<inf>28.15</inf>)·z·H<inf>2</inf>O for Tushig Mountain sample. • (Na<inf>2.34</inf>, K<inf>1.48</inf>, Mg<inf>0.86</inf>, Ca<inf>0.57</inf>, Fe<inf>0.62</inf>)(Al<inf>7</inf>O<inf>29.03</inf>) (Si<inf>29.07</inf>O<inf>29.03</inf>)·z·H<inf>2</inf>O for Urgun deposit sample. • (Na<inf>2.14</inf>, K<inf>1.64</inf>, Mg<inf>0.53</inf>, Fe<inf>0.64</inf>, Ti<inf>0.19</inf>)(Al<inf>6.38</inf>O<inf>28.95</inf>) (Si<inf>30.59</inf>O<inf>28.95</inf>)·z·H<inf>2</inf>O for Bayan Zurh Black Mountain sample. • (Na<inf>3.59</inf>, K<inf>1.17</inf>, Ca<inf>1.17</inf>, Mg<inf>0.68</inf>, Fe<inf>0.30</inf>)(Al<inf>6.58</inf>O<inf>28.90</inf>) (Si<inf>28.65</inf>O<inf>28.90</inf>)·z·H<inf>2</inf>O for Mandalovoo sample.