The elemental and molecular composition of mineral matter in five wood types and two barks was investigated as a function of temperature using thermal gravimetric analysis, differential thermal analysis, inductively coupled plasma emission spectroscopy, and X-ray diffraction. Low temperature ash was prepared at 500°C, and samples were heated in a tube furnace at temperature increments to 1400°C. The dissociation of carbonates and the volatilization of potassium, sulfur, and trace amounts of copper and boron were investigated as a function of temperature. Overall mass loss of the mineral ash ranged from 23–48% depending on wood type. The mass of K, S, B, Na, and Cu decreased, whereas Mg, P, Mn, Al, Fe, and Si did not change with temperature relative to Ca which was assumed to be constant. Sintering of the ash occurred, but fusion of the ash did not occur. In the 600°C ash CaCO 3 and K 2 Ca(CO 3 ) 2 were identified, whereas in 1300°C ash CaO and MgO were the main compounds. The implications for ash deposition in furnaces is discussed.

https://www.fpl.fs.fed.us/documnts/pdf1993/misra93a.pdf

Wood ash composition as a function of furnace temperature

Chemical study of extracted rockrose and of chars and activated carbons prepared at different temperatures

Electrical conductivity of cementitious materials with a wide range of chemical compositions has been studied during the first 24 h of hydration. Relationships between heat of hydration and electrical conductivity curves are discussed. Results are tentatively explained in terms of some physical and chemical parameters. Further evidence that the electrical conductivity of hydrating cement pastes is related to the hydration mechanisms operating in these systems was obtained. The order in which the cations of inorganic admixtures (chlorides and hydroxides) were found to increase the peak and rate of development of the electrical conductivity is the same order that they have been found to increase the heat liberated upon hydration of systems containing these admixtures.

Influence of chemical composition and inorganic admixtures on the electrical conductivity of hydrating cement pastes

Phase relations in the system K2CO3-CaCO3 have been studied in the compositional range, X (K2CO3), from 100 to 10 mol%, at 6.0 GPa and 900–1450 °C. At 900–950 °C, the system has three intermediate compounds: K6Ca2(CO3)5, K2Ca(CO3)2, and K2Ca3(CO3)4. The K2Ca(CO3)2 compound decomposes to the K6Ca2(CO3)5 + K2Ca3(CO3)4 assembly above 950 °C. The K6Ca2(CO3)5 and K2Ca3(CO3)4 compounds melt congruently slightly above 1200 and 1300 °C, respectively. The eutectics were established at 64 and 44 mol% near 1200 °C and at 23 mol% near 1300 °C. K2CO3 remains as a liquidus phase at 1300 °C and 75 mol% and melts at 1425 ± 20 °C. Aragonite remains as a liquidus phase at 1300 °C and 20 mol% and at 1400 °C and 10 mol%. CaCO3 solubility in K2CO3 and K2CO3 solubility in aragonite are below the detection limit (<0.5 mol%).

Infiltration of subduction-derived K-rich Ca-Mg-Fe-carbonatite into the Fe-saturated mantle causes the extraction of (Mg,Fe)CO3 components from the melt, which shifts its composition toward K-Ca-carbonatite. According to our data this melt can be stable at the P-T conditions of subcratonic lithosphere with geothermal gradient of 40 mW/m2 corresponding to temperature of 1200 °C at 6 GPa.

/pdf/phase-relationships-in-the-system-k2co3-caco3-at-6-gpa-and-42cs3qvdz3.pdf

Phase relationships in the system K2CO3-CaCO3 at 6 GPa and 900-1450 °C

LiMn2O4 spinel is one of the most promising cathode materials for lithium-ion batteries because of its cheapness and eco-friendliness. Due to Jahn-Teller distortion, the capacity fades, however, upon repeated cycling. Attempts are being made to improve the cycle life of the spinel by substitution of manganese with other cations. In this paper we report the effect of partial substitution of manganese by Mg2+ ions in the LiMn2O4 phase. LiMgyMn2−yO4 (y=0 – 0.3) has been synthesized by a thermal method and characterized using XRD, TG/DTA and FTIR. The electrochemical performance is correlated with the dopant concentration.

Significance of Mg doped LiMn2O4 spinels as attractive 4 V cathode materials for use in lithium batteries

https://link.springer.com/content/pdf/10.1007/BF00720025.pdf

Kinetic study of thermal decomposition of calcium carbonate in the presence of K2CO3 and BaCO3

Variations in specific conductivity during hydration and setting of cements and clinker minerals have been reported. Measurements on the specific conductivity, for 48 hrs at regular intervals, of the suspensions of cement with adequate W/C ratio have shown two peaks in a plot of time vs specific conductivity and only one peak in case of clinker mineral. The effect of gypsum additive on specific conductivity during hydration of cement is also described. Suitable explanations for variations in conductivity, and effect of gypsum on conductivity, during hydration and setting of cements have been proposed.

R. S. Gupta

Papers

Kinetic study of thermal decomposition of calcium carbonate in the presence of K2CO3 and BaCO3

Changes in Electrical Properties during Hydration and Setting of Cements