Radiation-induced paramagnetic centers whose unpaired electron is localized on a phosphorus ion were investigated with ESR in glassy and polycrystalline metaphosphates. Hyperfine doublet absorptions due to a 31P nucleus with a separation of 70-120mT were analyzed.The mean values and fluctuation widths of ESR parameters for the centers in the glasses were determined by the lineshape simulation of the observed spectra. The results obtained are summarized as follows:(1) AP4+ center having fourfold coordination was observed in the as-irradiated (77K) glassy and polycrystalline hosts. This center is considered to be derived from a PO4 unit on capturing an electron.(2) On thermal annealing of as-irradiated glasses, the above center is converted into a P4+ center having threefold coordination of C3 symmetry, detaching an oxygen from its coordination sphere. The resulting defect center is an analogue of Si E-center, the unpaired electron occupying a non-bonding level which is exclusively composed of sp3 hybrid orbital of phosphorus.(3) The formation of the fourfold-coordinated center and its thermal relaxation into the threefold-coordinated one are identical with the results of As (V) which has an electronic configuration analogous to P (V). It is suggested that these results are the common characteristics of NWFs which belong to the V group on the periodic table. This fact may be ascribed to that these NWFs provide a coulombic potential for an electron trapping because their valence is greater than its coordination number.[

New manganese arsenides CsMnAs, RbMnAs, and KMnAs were synthesized by solid-state reaction. They consist of edge-sharing MnAs tetrahedra, which are a building block similar to those of Fe-based superconductors. CsMnAs and RbMnAs adopt the KCuS-type structure (tetragonal P4/ mmm space group, No. 123) with a MnAs double layer, while KMnAs has the CaFeAs-type structure (orthorhombic Pnma space group, No. 62) with a MnAs tunnel framework. The structural change from CsMnAs and RbMnAs to KMnAs as well as the structural trend of the other ternary A-Mn-As (A = alkali metal) and AE-Mn-As (AE = alkaline-earth metal) compounds is understood as a consequence of reduction of the coordination number around the A and AE sites owing to the decrease of the ionic radius from Cs to Mg. Electrical resistivity measurements confirm that the three new phases are Mott insulators with band gaps of 0.52 (CsMnAs), 0.43 (RbMnAs), and 0.31 eV (KMnAs). Magnetic and heat capacity measurements revealed that CsMnAs and RbMnAs are antiferromagnets without apparent phase transitions below 400 K, which is similar to the magnetism of LaMnAsO and BaMnAs, while the existence of the ferromagnetic component was indicated in KMnAs with a magnetic transition at 179 K.

Species of electrical charge carriers in oxide glasses containing neither alkali ions nor transition metal ions is the subject of considerable uncertainty. Two different approaches adopted here made it clear that protons in 45BaO-55P205 glasses are the charge carriers. One approach adopted is of a change in color by formation of H~WOs, which was caused by injection of the protons of the glass into WO3 thin film under an electrical field, and the other is of a change in electrical conductivity by H+-D + substitution in the glasses.