Defects and Their Distribution in KH2PO4 Crystals with Embedded TiO2 Nanoparticles

2015 ◽  
Vol 1806 ◽  
pp. 13-18 ◽  
Author(s):  
Valentin Grachev ◽  
Romand Tse ◽  
Ian Vrable ◽  
Igor Pritula ◽  
Olga Bezkrovnaya ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Wave Excitation ◽  
Growth Sector ◽  
Paramagnetic Resonance ◽  
Line Intensities ◽  
Anatase Nanoparticles ◽  
Index Changes ◽  
Electron Paramagnetic ◽  
Kdp Crystals

ABSTRACTResults from the successful growth of high quality KH2PO4 (KDP) crystals with incorporated TiO2 anatase nanoparticles and the characterization of these crystals using several complementary methods are presented. Transmission and scanning electron microscopy have shown that the anatase nanoparticles were captured mainly by the pyramidal growth sector and, to a considerably lesser extent, by the prismatic growth sector. Energy dispersive x-ray analysis confirms that the growth layer stacks contain the TiO2 particles. Significant variation in the imaginary and real parts of the cubic nonlinear optical susceptibilities and refractive index changes at continuous wave excitation were found in prism and pyramid parts of pure KDP and KDP:TiO2 samples. The identified lines of electron paramagnetic resonance belong to four different centers FeA3+, FeB3+, CrR3+ and CrGB3+. From analysis of line intensities it was concluded that the concentration of non-controlled impurities in nominally pure KDP samples is several times larger than in KDP:TiO2, and that the concentration of non-controlled impurities in the prismatic part of the KDP:TiO2 boule is larger than in the pyramidal part.

scholarly journals Scalable microresonators for room-temperature detection of electron spin resonance from dilute, sub-nanoliter volume solids

2020 ◽  
Vol 6 (44) ◽  
pp. eabb0620
Author(s):  
Nandita Abhyankar ◽  
Amit Agrawal ◽  
Pragya Shrestha ◽  
Russell Maier ◽  
Robert D. McMichael ◽  
...  
Keyword(s):  
Room Temperature ◽  
Continuous Wave ◽  
Perovskite Oxide ◽  
Paramagnetic Resonance ◽  
Microwave Resonance ◽  
Temperature Detection ◽  
Spin Resonance ◽  
Low Levels ◽  
Electron Paramagnetic

We report a microresonator platform that allows room temperature detection of electron spins in volumes on the order of 100 pl, and demonstrate its utility to study low levels of dopants in perovskite oxides. We exploit the toroidal moment in a planar anapole, using a single unit of an anapole metamaterial architecture to produce a microwave resonance exhibiting a spatially confined magnetic field hotspot and simultaneously high quality-factor (Q-factor). To demonstrate the broad implementability of this design and its scalability to higher frequencies, we deploy the microresonators in a commercial electron paramagnetic resonance (EPR) spectrometer operating at 10 GHz and a NIST-built EPR spectrometer operating at 35 GHz. We report continuous-wave (CW) EPR spectra for various samples, including a dilute Mn2+-doped perovskite oxide, CaTiO3, and a transition metal complex, CuCl2.2H2O. The anapole microresonator presented here is expected to enable multifrequency EPR characterization of dopants and defects in perovskite oxide microcrystals and other volume-limited materials of technological importance.

Structural and electron paramagnetic resonance (EPR) characterization of novel vanadium(V/IV) complexes with hydroquinonate-iminodiacetate ligands exhibiting “noninnocent” activity

2012 ◽  
Vol 85 (2) ◽  
pp. 329-342 ◽  
Author(s):  
Chryssoula Drouza ◽  
Marios Stylianou ◽  
Petri Papaphilippou ◽  
Anastasios D. Keramidas
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Continuous Wave ◽  
Semiquinone Radical ◽  
Paramagnetic Resonance ◽  
Amine Nitrogen ◽  
Coordination Environment ◽  
X Ray Crystallography ◽  
X Band ◽  
Electron Paramagnetic

Reaction of KVO3 with 2-[N,N'-(carboxymethyl)aminomethyl]-5-methylhydroquinone (H4mecah) in aqueous solution at pH 8.2 results in the isolation of mononuclear K2[VV(O)2{Hmecah(-3)}]·2H2O complex. On the other hand, reaction with the 2-[N,N'-(carboxymethyl)aminomethyl]-5-tert-butylhydroquinone (H4tbutcah) under the same conditions gives the tetranuclear mixed-valent complex K6[{VVO(μ-O)VIVO}{μ-tbutbicah(-6)}]2·10.5H2O (H6tbutbicah, 2,2'-({2-[bis(carboxymethyl)amino]-3,6-dihydroxy-4-methylbenzyl}azanediyl)diacetic acid). The structures of both complexes were determined by single-crystal X-ray crystallography. The coordination environment of vanadium ions in both complexes is octahedral, with four out of the six positions to be occupied by the two cis carboxylate oxygens, one hydroquinonate oxygen, and one amine nitrogen atoms of the ligands’ tripod binding sites. The importance of the chelate ring strains in the stabilization of the p-semiquinone radical is also discussed. A protonation of the ligated to vanadium(IV) ion hydroquinonate oxygen at low pH was revealed by continuous wave (cw) X-band electron paramagnetic resonance (EPR) and UV–vis spectroscopies.

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