China
Africa
Explore chapters and articles related to this topic
Characteristics of the Metal–Metal Oxide Reaction Matrix
Published in Anthony Peter Gordon Shaw, Thermitic Thermodynamics, 2020
Sodium bismuthate, NaBiO3, is an extraordinary oxidizer that contains bismuth in the +5 oxidation state [38]. The commercial product is reportedly an impure, moisture-sensitive, yellow or brown powder that dissolves in acidic solutions to form an uncharacterized Bi5+ complex [39]. Manganese and manganese compounds are oxidized to permanganate in such solutions. Thus, NaBiO3 is a stronger oxidizer than KMnO4. There do not appear to be any reports concerning the use of powdered NaBiO3 in pyrotechnic compositions.
Hydrothermal synthesis of KTi2(PO4)3, α-Ti(HPO4)2·H2O and γ-Ti(PO4)(H2PO4)·2H2O from a lepidocrocite-type titanate
Published in Journal of Asian Ceramic Societies, 2019
Nobuhiro Kumada, Akihito Imase, Sayaka Yanagida, Takahiro Takei, Akira Miura, Nobuki Itoi, Toshiki Goto
Hydrothermal or solvothermal reaction is an attractive synthesis method for inorganic compounds or inorganic-organic complexes, particularly new compounds. We have reported hydrothermal synthesis and crystal structure analysis for new zirconium phosphates and new bismuth oxides [1]. A variety of bismuthates were synthesized by low-temperature hydrothermal reactions using a hydrate sodium bismuthate, NaBiO3·nH2O [2–24]. These bismuthates had never been prepared by high-temperature solid-state reaction. As for zirconium phosphates, seven types of zirconium phosphates were obtained by hydrothermal reaction using a hydrate zirconium oxychloride, ZrOCl2·8H2O [25–29]. The structural features of these zirconium phosphates can be described as one-, two- or three-dimensional structures built up by corner-sharing of ZrO6 octahedra and PO4 tetrahedra. Both bismuthates and zirconium phosphates with a variety of crystal structures were obtainable from only one kind of starting compound, and this capability is one of the attractive aspects of hydrothermal synthesis. For this work, we chose a layered lepidocrocite-type titanate as one of the starting compounds for hydrothermal synthesis, in which alkaline ions in the interlayer are ion-exchangeable [30,31]. Hydrothermal reaction with this starting compound in H3PO4 solution produced KTi2(PO4)3, and by using the protonated titanate derived from lepidocrocite-type potassium titanate, α-Ti(HPO4)2·H2O and γ-Ti(PO4)(H2PO4)·2H2O were obtained. Potassium titanium phosphate, KTi2(PO4)3, has a NASICON-like rhombohedral structure [32], and this structural type is adopted in AM2(PO4)3 (A; Na, K, M; Ti, Zr). It was reported that some of these exhibited a low thermal expansion coefficient [33–35], but, the thermal expansion coefficient of KTi2(PO4)3 has not yet been reported. On the other hand, layered titanium phosphates [36], α-Ti(HPO4)2·H2O and γ-Ti(PO4)(H2PO4)·2H2O, have the same crystal structures of α-Zr(HPO4)2·H2O [37] and γ-Zr(PO4)(H2PO4)·2H2O [38], respectively, and various synthetic methods have been reported for both layered titanium phosphates [39–42]. This paper describes a new synthetic route to both layered titanium phosphates using a lepidocrocite-type potassium titanate.