Properties Of Alkaline-earth Metals Research Articles

Synthesis, structures and properties of alkaline earth metal benzene-1,4-dioxylacetates with three-dimensional hybrid networks

Three novel alkaline earth metal benzene-1,4-dioxylacetates M(L)H 2O (M = Ca, Sr or Ba, L = benzene-1,4-dioxylacetate) with three-dimensional (3D) hybrid frameworks were reported. Both Ca(L)H 2O ( 1) and Sr(L)H 2O ( 2) crystallize in the monoclinic space group P2 1/ c while Ba(L)H 2O ( 3) in the monoclinic space group P2 1. As determined by X-ray single-crystal analysis, in these compounds each metal ion is coordinated by eight O atoms: four from different carboxylate groups, two from one carboxylate group, one from the ether oxygen and one from one water molecule. Each L 2− ligand coordinates to five alkaline earth metal centers through one of its ether oxygen atoms and two carboxylate groups adopting novel μ 3-η 2:η 2-bridging and μ 2-η 1:η 1-bridging coordination modes to give rise to a 3D network. The luminescence analysis shows that complexes 1 and 2 exhibit fluorescence in the solid state at room temperature.

Application of Barium-bearing Alloys in Steelmakig.

Based on the understanding of the physico-chemical properties of alkaline earth metals, an overview on the investigation of application of Ba-bearing alloys in steel is given in the paper. As calcium it is, barium has a strong affinity for oxygen and sulfur in steel; barium can also modify the inclusions in the steel. The barium-bearing inclusions easily float out from steel. The residual barium-bearing inclusions exist in spherical complex aluminates and randomly distribute in the steel. The mechanical properties such as fatigue, transverse impact toughness and anisotropic properties of steels treated with barium-bearing alloys are improved. The effect of calcium and barium on microstructure of steel is discussed. Some characteristics of production of barium-bearing alloys are also discussed.

Compatibility of alkaline earth metal (Mg, Ca, Sr)-doped lanthanum chromites as separators in planar-type high-temperature solid oxide fuel cells

The mechanical, electrical and thermal properties of alkaline earth metal (Mg, Ca and Sr)-doped LaCrO3 have been examined as separators in planar-type high-temperature solid oxide fuel cells. The maximum three-point bending strength at 1000°C in air was measured and found to be 186 MPa for LaCr0.9Mg0.1O3, 36 MPa for La0.9Ca0.1CrO3 and 77 MPa for La0.9Sr0.1CrO3. The La0.8Sr0.2CrO3 separator placed in both an oxidizing and a reducing environment at 1000°C showed almost the same electrical conductivities of the H2 atmosphere, and the conductivity was independent of sample thickness in the range 0.5–3.0 mm. For all the doped LaCrO3 perovskites, a difference between the thermal expansion behaviours of air and the H2 atmosphere was observed. In particular, the thermal expansion slope for the first heating cycle under the H2 atmosphere showed a marked change. The volume changes were due to the formation of oxygen defects in the perovskite structure.

Mechanical and Electrical Properties of Alkaline Earth Metal Doped Lanthanum Chromites

Mechanical and electrical properties of alkaline earth metal doped lanthanum chromites have been investigated. The 3-point bending strength at 1000 °C was measured to be 19.0 kgf/mm2 for La(Cr0.9Mg0.1)O3, 3.7 kgf/mm2 for (La0.9Ca0.1)CrO3 and 7.9 kgf/mm2 for (La0.9Sr0.1)CrO3. The highest electrical conductivity of 12.1 S/cm at 1000 °C was obtained for (La0.9Ca0.1)CrO3 in air. In reducing atmosphere, the conductivity decreased, and the highest conductivity was 2.70 S/cm at 1000 °C for (La0.9Ca0.1)CrO3 in H2

General study of the thermophysical properties of alkaline earth metals

Several experimental devices are used to measure the density, surface tension, viscosity, and heat capacity of barium, calcium, and cesium from their melting points to 1800°K. Measurement methods are described and results presented.