Thermal hysteresis at the low temperature phase transition of ammonium dihydrogen phosphate, ammonium dihydrogen arsenate, their deuterated analogs, and of potassium dihydrogen phosphate and the effect of chromium impurity ions on the transition temperature

1979 ◽  
Vol 83 (6) ◽  
pp. 664-669 ◽  
Author(s):  
S. R. Gough ◽  
J. A. Ripmeester ◽  
N. S. Dalal ◽  
A. H. Reddoch
1998 ◽  
Vol 327-329 ◽  
pp. 391-394
Author(s):  
Keiichi Ikegami ◽  
Shin-ichi Kuroda ◽  
Tomoyuki Akutagawa ◽  
Taro Konuma ◽  
Takayoshi Nakamura ◽  
...  

1970 ◽  
Vol 41 (2) ◽  
pp. 836-838 ◽  
Author(s):  
Mitsuoki Nakahira ◽  
Shigeo Horiuchi ◽  
Hirotoshi Ooshima

2014 ◽  
Vol 809-810 ◽  
pp. 477-484
Author(s):  
Zhao Qing Qi ◽  
Hong Tao Wang ◽  
Jun Liang Dang ◽  
Shi Hao Zhang ◽  
Jian Hua Ding

The capacity of 10%, 30%, and 50% ammonium dihydrogen phosphate were replaced with an equal amount of three phosphate (potassium dihydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate) respectively. Magnesium phosphate cement was made by phosphate of replaced, which strength, setting time, fluidity, hydration temperature, and the hydration products was researched. The results show that: MPC was made that replaced with the equal amount of three kind of phosphate, which has good mechanical properties. Setting time and fluidity change along with the replacment. Three kind of phosphate replace ammonium dihydrogen phosphate, which change the hydration process of MPC. When ammonium dihydrogen phosphate was replaced by an equal amount of disodium hydrogen phosphate, the temperature of hydration is only 69.4 °C. XRD showed that the diffraction peaks of composite’s magnesium phosphate cement increases.


Author(s):  
Khai-Nghi Truong ◽  
Carina Merkens ◽  
Martin Meven ◽  
Björn Faßbänder ◽  
Richard Dronskowski ◽  
...  

Single-crystal neutron diffraction experiments at 100 and 2.5 K have been performed to determine the structure of 3-(pyridin-4-yl)pentane-2,4-dione (HacacPy) with respect to its protonation pattern and to monitor a low-temperature phase transition. Solid HacacPy exists as the enol tautomer with a short intramolecular hydrogen bond. At 100 K, its donor···acceptor distance is 2.450 (8) Å and the compound adopts space group C2/c, with the N and para-C atoms of the pyridyl ring and the central C of the acetylacetone substituent on the twofold crystallographic axis. As a consequence of the axial symmetry, the bridging hydrogen is disordered over two symmetrically equivalent positions, and the carbon–oxygen bond distances adopt intermediate values between single and double bonds. Upon cooling, a structural phase transition to the t 2 subgroup P\bar 1 occurs; the resulting twins show an ordered acetylacetone moiety. The phase transition is fully reversible but associated with an appreciable hysteresis in the large single crystal under study: transition to the low-temperature phase requires several hours at 2.5 K and heating to 80 K is required to revert the transformation. No significant hysteresis is observed in a powder sample, in agreement with the second-order nature of the phase transition.


2011 ◽  
Vol 41 (2-4) ◽  
pp. 363-370
Author(s):  
Alisa Chernenkaya ◽  
Marina Kirman ◽  
Alexei Dmitriev ◽  
Roman Morgunov ◽  
Oksana Koplak ◽  
...  

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