12003-63-3Relevant articles and documents
Cristobalite-Related Phases in the KAlO2-KAlSiO4 System
Husheer, Shamus L. G.,Thompson, John G.,Melnitchenko, Alexandra
, p. 624 - 630 (1999)
A study of the K-rich end of the potassium aluminate-silica system (K1-xAl1-xSixO2; 0≤x≤0.25) at temperatures up to 1500°C has confirmed the existence of a cubic cristobalite-type solid solution extending to x≈0.235 at 1500°C. The end member, KAlO2, transforms on cooling to an orthorhombic KGaO2-type structure at 531°C (orthorhombic Pbca: a=5.4327(8), b=10.924(2), c=15.469(2) A, Z=16). The room temperature structure has been modeled using chemically restrained refinement of Guinier-Haegg X-ray powder diffraction (XRD) data by the Rietveld method (reduced χ2=0.074, wRp=0.065, Rp=0.049). With progressive substitution of SiO2 into KAlO2 the cubic-to-orthorhombic phase transition temperature is lowered. A new cristobalite-related phase field has been identified as existing close to room temperature between x≈0.10 and 0.125. The XRD data for this phase can be indexed to a tetragonal superstructure with ar=2√2ap and cr=2cp (r=resultant, p=parent). Analysis of K-rich specimens by XRD and differential scanning calorimetry required extreme care to avoid rapid degradation by atmospheric moisture.
Electron beam stimulated chemical reaction in solids
Lyakhov,Boldyrev,Voronin,Gribkov,Bochkarev,Rusakov,Auslender
, p. 21 - 31 (1995)
Use of electron beams allows to obtain new effects in high temperature chemistry of solid state. A stimulated influence of irradiation at comparable temperature conditions may be a subject of technological interest taking into account that increase of reaction rate can reach significant values.
A thermogravimetric and infrared emission spectroscopic study of alunite
Frost,Wain, Daria
, p. 267 - 274 (2008)
Thermogravimetric and differential thermogravimetric analysis has been used to characterize alunite of formula [K2(Al3+) 6(SO4)4(OH)12]. Thermal decomposition occurs in a series of steps (a) dehydration up to 225°C, (b) well defined dehydroxylation at 520°C and desulphation which takes place as a series of steps at 649, 685 and 744°C. The alunite minerals were further characterized by infrared emission spectroscopy (IES). Well defined hydroxyl stretching bands at around 3463 and 3449 cm-1 are observed. At 550°C all intensity in these bands is lost in harmony with the thermal analysis results. OH stretching bands give calculated hydrogen bond distances of 2.90 and 2.84-7 A. These hydrogen bond distances increase with increasing temperature. Characteristic (SO4)2- stretching modes are observed at 1029.5, 1086 and 1170 cm-1. These bands shift to lower wavenumbers on thermal treatment. The intensity in these bands is lost by 550°C.
Features of the synthesis of nanoparticles of Yttrium Oxide Y2O3:Nd
Tolstikova,Mikhailov,Smirnov
, (2014)
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