Growth and optical properties of transition metal oxides single crystal solid solutions
Abstract NiO, CoO, MnO single crystals and single crystal solid solutions of Ni c Mg 1− c O, Co c Mg 1− c O and Mn c Mg 1− c O were grown by the method of chemical transport reaction (the “sandwich” technique). The nature of the observed absorption and luminescence bands is explained in terms of the electronic transition of bivalent nickel, cobalt and manganese. The fine structure of the observed bands in NiO and MnO are connected to the pure exciton transition and to the exciton-magnon excitation.
Optical absorption of MgO:Mn
Wavelength-modulated absorption measurements on MgO:Mn show the presence of Mn3+ and Mn2+. The lowest spin-allowed transition of Mn3+ occurs at 520 nm. Weak bands at 301, 356, 389 and 426 nm are attributed to transitions from 6A1g to the 4T1g(P), 4T2g(D), 4Eg(G)+4T2g(G) and 4T2g(G) states of Mn2+, respectively. The latter band shows four zero-phonon lines with an over-all splitting of 34 cm-1 revealing a spin-orbit splitting of the 4T2g(G) state reduced by a factor of four by the action of a dynamic Jahn-Teller effect. Stress experiments indicate that the dominating Jahn-Teller interaction is with T2 symmetry vibrations.
Preparation and performance evaluation of swine manure bio-oil modified rubber asphalt binder
Abstract In order to study the effect of the preparation process of swine manure bio-oil modified rubber asphalt binder on the rheological properties of the binder, the matrix asphalt and asphalt rubber were used as the control group, and swine manure bio-oil modified rubber asphalt binders were obtained by three preparation processes. Then the rheological properties of five binders were evaluated by rotational viscosity, DSR, MSCR and BBR tests. The results show that the addition of swine manure bio-oil to asphalt rubber is beneficial to the workability, but cause negative effect on its high temperature performance, fatigue performance and low temperature crack resistance. The preparation method of premixing bio-oil and rubber powder can reduce the degradation of high-temperature performance of asphalt rubber caused by addition of swine manure bio-oil to a certain extent. The fatigue properties of the three bio-binders are close, and the critical temperature is less than 25 °C. The process of premixing bio-oil and rubber powder will increase the creep stiffness and reduce the low-temperature performance. However, the low-temperature performance of the binder obtained by this process is still better than that of the matrix asphalt and can meet the requirements of use. Therefore, it is recommended to use the preparation process of premixing bio-oil and rubber powder to prepare swine manure bio-oil modified asphalt rubber.