TY - JOUR
T1 - Defect states and morphological evolution in mechanically processed ZnO +
T2 - X C nanosystems as studied by EPR and photoluminescence spectroscopy
AU - Kakazey, M.
AU - Vlasova, M.
AU - Juarez-Arellano, E. A.
AU - Torchynska, T.
AU - Basiuk, V. A.
N1 - Publisher Copyright:
This journal is © The Royal Society of Chemistry 2016.
PY - 2016
Y1 - 2016
N2 - An evolution of electron paramagnetic resonance (EPR) and photoluminescence (PL) spectra of various active states (hydrogen donor DH EPR centers, Zn vacancy-related EPR centers, EPR DS centers from shallow donors (g = 1.9640) in ZnOW, Mn2+ ions in ZnOZB, C EPR centers in carbon nanoparticles, forming the near-band-edge (NBE) PL emission, PL emission typical for Zn-, O- and N-enriched ZnOW particles, as well as oxidized carbon nanodots (OCN)) was observed in the mixtures of ZnO + xC nanoparticles during prolonged high-energy mechanical processing (MP) in a hermetically sealed grinding chamber. The results of EPR and PL spectroscopy, X-ray diffraction analysis, as well as morphological analysis by means of atomic force microscopy (AFM) and laser particle sizer (LPS) measurements show a wide variety of interrelated series-parallel processes in the samples with increasing MP processing time (tMP). These processes include: (a) dramatic reduction in intensity of the DH EPR signal and PL bands at 3.14 (1.57), 2.53 and 2.3 eV during the first minutes of MP, which correlate with sample disaggregation; (b) grinding of ZnO particles and formation of Zn vacancy-related EPR centers in the area of destruction (AD); (c) an increase in sample temperature; (d) annealing of the Zn vacancy-related EPR centers formed; (e) initiation of carbon nanoparticle interaction with oxygen in the grinding chamber; (f) formation and growth of the EPR signal due to carbon nanoparticles; (g) formation of a reducing environment in the grinding chamber; (h) stabilization of donor DS-centers in AD of ZnO nanoparticles; (i) an increase in CO concentration in the grinding chamber; (j) inhibition of DS paramagnetic centers in ZnO; (k) initiation of the EPR signals due to Mn2+ ions in ZnOZB sphalerite phase in the sample with the lowest carbon content; (l) inhibition of nitrogen PL centers in ZnO; (m) the formation of oxidized carbon nanodots (OCN) showing a PL band at 2.8 eV. A detailed analysis for the localization of EPR and PL centers in the MP samples is presented.
AB - An evolution of electron paramagnetic resonance (EPR) and photoluminescence (PL) spectra of various active states (hydrogen donor DH EPR centers, Zn vacancy-related EPR centers, EPR DS centers from shallow donors (g = 1.9640) in ZnOW, Mn2+ ions in ZnOZB, C EPR centers in carbon nanoparticles, forming the near-band-edge (NBE) PL emission, PL emission typical for Zn-, O- and N-enriched ZnOW particles, as well as oxidized carbon nanodots (OCN)) was observed in the mixtures of ZnO + xC nanoparticles during prolonged high-energy mechanical processing (MP) in a hermetically sealed grinding chamber. The results of EPR and PL spectroscopy, X-ray diffraction analysis, as well as morphological analysis by means of atomic force microscopy (AFM) and laser particle sizer (LPS) measurements show a wide variety of interrelated series-parallel processes in the samples with increasing MP processing time (tMP). These processes include: (a) dramatic reduction in intensity of the DH EPR signal and PL bands at 3.14 (1.57), 2.53 and 2.3 eV during the first minutes of MP, which correlate with sample disaggregation; (b) grinding of ZnO particles and formation of Zn vacancy-related EPR centers in the area of destruction (AD); (c) an increase in sample temperature; (d) annealing of the Zn vacancy-related EPR centers formed; (e) initiation of carbon nanoparticle interaction with oxygen in the grinding chamber; (f) formation and growth of the EPR signal due to carbon nanoparticles; (g) formation of a reducing environment in the grinding chamber; (h) stabilization of donor DS-centers in AD of ZnO nanoparticles; (i) an increase in CO concentration in the grinding chamber; (j) inhibition of DS paramagnetic centers in ZnO; (k) initiation of the EPR signals due to Mn2+ ions in ZnOZB sphalerite phase in the sample with the lowest carbon content; (l) inhibition of nitrogen PL centers in ZnO; (m) the formation of oxidized carbon nanodots (OCN) showing a PL band at 2.8 eV. A detailed analysis for the localization of EPR and PL centers in the MP samples is presented.
UR - http://www.scopus.com/inward/record.url?scp=84976590371&partnerID=8YFLogxK
U2 - 10.1039/c6ra12190j
DO - 10.1039/c6ra12190j
M3 - Artículo
SN - 2046-2069
VL - 6
SP - 58709
EP - 58722
JO - RSC Advances
JF - RSC Advances
IS - 63
ER -