scholarly journals “Restricted Geometry” Effect on Phase Transitions in KDP, ADP, and CDP Nanocrystals

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 593
Author(s):  
Vladislav V. Tarnavich ◽  
Alexander S. Sidorkin ◽  
Tatiana N. Korotkova ◽  
Ewa Rysiakiewicz-Pasek ◽  
Leonid N. Korotkov ◽  
...  

The dielectric properties of composite materials prepared by the embedding of ferroelectrics potassium dihydrogen phosphate (KDP), cesium dihydrophosphate (CDP), as well as antiferroelectric ammonium dihydrogen phosphate (ADP) into porous glass matrices with an average size of through pores of 7, 46, and 320 nm have been studied. It was found that an increase occurred in the phase transitions temperature (TC) for embedded particles in comparison with corresponding bulk materials. Some possible mechanisms of influence of “restricted geometry” on the Curie temperature are discussed. Estimates of TC shifting as a result of the “pressure effect” caused by elastic stresses in embedded particles as well as the result of bias electric field influence arising due to the piezoelectric effect are made. The possibility of using the tunneling Ising model to explain the experimental results is discussed.

1985 ◽  
Vol 40 (11) ◽  
pp. 1164-1166
Author(s):  
O. P. Agarwal ◽  
Prem Chand

Results of the optical absorption study of vanadyl ion doped in magnesium ammonium sulphate hexahydrate, rubidium sulphate and potassium dihydrogen phosphate single crystals at RT are reported. The nature of optical bands suggests a C4v symmetry of the Vanadyl complexes in conformity with the EPR results. Powder EPR data and optical data are correlated to obtain the MO coefficients.


Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 369
Author(s):  
Jianhui Mao ◽  
Wenjun Liu ◽  
Dongfang Li ◽  
Chenkai Zhang ◽  
Yi Ma

As an excellent multifunctional single crystal, potassium dihydrogen phosphate (KDP) is a well-known, difficult-to-process material for its soft-brittle and deliquescent nature. The surface mechanical properties are critical to the machining process; however, the characteristics of deformation behavior for KDP crystals have not been well studied. In this work, the strain rate effect on hardness was investigated on the mechanically polished tripler plane of a KDP crystal relying on nanoindentation technology. By increasing the strain rate from 0.001 to 0.1 s−1, hardness increased from 1.67 to 2.07 GPa. Hence, the strain rate sensitivity was determined as 0.053, and the activation volume of dislocation nucleation was 169 Å3. Based on the constant load-holding method, creep deformation was studied at various holding depths at room temperature. Under the spherical tip, creep deformation could be greatly enhanced with increasing holding depth, which was mainly due to the enlarged holding strain. Under the self-similar Berkovich indenter, creep strain could be reduced at a deeper location. Such an indentation size effect on creep deformation was firstly reported for KDP crystals. The strain rate sensitivity of the steady-state creep flow was estimated, and the creep mechanism was qualitatively discussed.


Author(s):  
A. Sivakumar ◽  
S. Sahaya Jude Dhas ◽  
P. Sivaprakash ◽  
Abdulrahman I. Almansour ◽  
Raju Suresh Kumar ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document