The ferroelastic monoclinic low temperature modification of ammonium hydrogen oxalate hemihydrate

1982 ◽  
Vol 158 (1-2) ◽  
Author(s):  
H. L. Keller
Keyword(s):  
Low Temperature ◽  
Temperature Modification ◽  
Ammonium Hydrogen

scholarly journals Crystal structure of the low-temperature modification of trilithium heptaarsenide, LT-Li3As7

2002 ◽  
Vol 217 (1) ◽  
pp. 485-486
Author(s):  
W. Hönle ◽  
J. Buresch ◽  
K. Peters ◽  
J. H. Chang ◽  
H. G. von Schnering
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Temperature Modification

Die Kristallstruktur von α-ΚΖnΡΟ4 / The Crystal Structure of α-KZnPO4

1992 ◽  
Vol 47 (9) ◽  
pp. 1249-1254 ◽  
Author(s):  
Martina Andratschke ◽  
Klaus-Jürgen Range ◽  
Heinz Haase ◽  
Ulrich Klement
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Low Temperature ◽  
Single Crystals ◽  
Potassium Ions ◽  
Space Group ◽  
Temperature Modification ◽  
Type Apparatus

Single crystals of a-KZnPO4, the low-temperature modification of potassium zinc orthophosphate, were obtained from KZnPO4 powder by high pressure experiments in a modified Belt-type apparatus. The crystals are hexagonal, space group P 63, with a = 18.155(2), c = 8.504(1) Å, c/a = 0.4684 and Z = 24. The crystal structure, refined from diffractometer data to R = 0.077, Rw = 0.068, comprises an ordered network of ZnO4 and PO4 tetrahedra with rings of six tetrahedra vertical to the c-axis. The potassium ions are located in cavities formed by the rings.

Low-temperature preparation of dense 10 mol%-Y2O3-doped CeO2 ceramics using powders synthesized via carbonate coprecipitation

2003 ◽  
Vol 18 (5) ◽  
pp. 1239-1246 ◽  
Author(s):  
Yarong Wang ◽  
Toshiyuki Mori ◽  
Ji-Guang Li ◽  
Takayasu Ikegami ◽  
Yoshiyuki Yajima
Keyword(s):  
Low Temperature ◽  
Ultrafine Particle ◽  
Particle Morphology ◽  
Molar Ratio ◽  
Low Temperature Preparation ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen ◽  
Final Yield ◽  
Carbonate Coprecipitation Method ◽  
Very Low Temperature

A carbonate coprecipitation method was used for the facile synthesis of highly reactive 10 mol%-Y2O3-doped CeO2 (20YDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE3+ (RE = Ce + Y) molar ratio (R) and the reaction temperature (T) significantly affect the final yield and precursor properties, including chemical composition and particle morphology. Suitable processing conditions are T = 60 °C and R = 2.5 to 10, under which precipitation is complete, and the resultant precursors show ultrafine particle size, spherical particle shape, and good dispersion. The thus-processed precursors are basic carbonates with an approximate formula of Ce0.8Y0.2(OH)CO3 · 2H2O, which directly yield oxide solid solutions upon thermal decomposition at a very low temperature of approximately 400 °C. The 20YDC solid-solution powders calcined at 700 °C show excellent reactivity and were densified to >99% of theoretical via pressureless sintering at a very low temperature of 950 °C for 6 h.

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