02765nas a2200253   4500008004100000022001400041245015000055210006900205260000800274300001200282490000800294520180700302653003902109653003502148653005102183653003602234100002302270700002002293700001902313700001502332700001502347700001802362856013102380       2018                        eng d  a1359-645400aReversible phase transformation phenomenon in titanium dioxide films: evidence beyond interface-nucleation and dissolution-precipitation kinetics0 aReversible phase transformation phenomenon in titanium dioxide f  cMAR  a253-2640 v1463 a<p>The re-crystallization kinetics and rutile to anatase reversible phase transformation (PT) in nano crystalline titanium dioxide (TiO2) are reported. Initially, an amorphous TiO2 film is used for the present study and in situ isothermal annealing dependent nucleation and growth kinetics of anatase and rutile phase is studied at low temperature (similar to 523 K) and well explained using Johnson Mehl AvramiKolmogorov (JMAK) model. The anatase nanocrystallite (NCs) transformation into rutile phase is reported with isothermal annealing for longer time and temperature dependent annealing in lower temperature range 523 K-673 K and explained using interface-nucleation mechanism. Furthermore, the thermodynamic stability of rutile NCs and lattice stress-induced reversible PT in nano-sized rutile TiO2 are confirmed in moderate temperature range (623 K- 973 K) and well explained using x-ray diffraction, micro-Raman spectroscopy and near edge x-ray absorption fine structure spectroscopy studies. However, annealing at higher temperature (1123 K- 1323 K) induces the growth of anatase NCs and their natural transform into rutile phase are explained by well-known dissolution precipitation mechanism. Activation energy of rutile PT is quantified and found higher for dissolution-precipitation mechanism than that for interface nucleation at earlier stage. Thus, overall PT kinetics at different temperature range is well understood by invoking in three step mechanism: 1) early stage anatase-to-rutile transformation is dominated by interface-nucleation, II) then intermediate stage reversible rutile-to-anatase PT and, Ill) at later stages, anatase-to-rutile PT is controlled by dissolution precipitation mechanism. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</p>10aDissolution-precipitation kinetics10aInterface-nucleation mechanism10aJohnson-Mehl-Avrami-Kolmogorov (JMAK) approach10aReversible phase transformation1 aGautam, Subodh, K.1 aSingh, Jitendra1 aShukla, D., K.1 aPippel, E.1 aPoddar, P.1 aSingh, Fouran  uhttps://library.ncl.res.in/content/reversible-phase-transformation-phenomenon-titanium-dioxide-films-evidence-beyond-interface02145nas a2200265   4500008004100000022001400041245015500055210006900210260000800279300001400287490000700301520116100308653002601469653003001495653003501525653003501560653003301595100002601628700002001654700002201674700001801696700002201714700001801736856012501754       2019                        eng d  a0018-938300aIn situ study of radiation stability and associated conduction mechanisms of Nb-Doped TiO2/p-Si heterojunction diode under swift heavy ion irradiation0 aIn situ study of radiation stability and associated conduction m  cMAR  a1475-14810 v663 a<p>In situ current-voltage characteristics of Nb-doped TiO2/p-Si-based heterojunction diode have been studied under dense electronic excitations of 84-MeV Si6+ ions. The diode parameters such as ideality factor (eta), barrier height (phi(B)), reverse saturation current (J(s)), and series resistance (R-s) are found to be a strong function of ion irradiation fluence. The observed anomalies of fluence dependence of barrier height and ideality factor are explained in terms of irradiation-induced created defects complexes, modification of interface states and structural properties of Nbdoped-TiO2 (NTO) layer. Several mechanisms suchas barrier height inhomogeneity, donor defects-induced enchantment in n-NTO layer conductivity, and various current conduction mechanisms involved at different voltage ranges are discussed as a function of fluence with the help of constructed energy band diagram. Such in situ studies on n-NTO/p-Si heterojunction diode under radiation harsh environment are very appropriate for the better understanding of heterojunction interface properties and make it suitable for use in aerospace industry and nuclear reactors.</p>
10aBarrier height tuning10an-NTO/p-Si heterojunction10aradiation stability of devices10asecondary electron irradiation10aspace-charge limited current1 aGautam, Subodh, Kumar1 aSingh, Jitendra1 aSingh, Ram, Gopal1 aGautam, Naina1 aTrivedi, Priyanka1 aSingh, Fouran  uhttps://library.ncl.res.in/content/situ-study-radiation-stability-and-associated-conduction-mechanisms-nb-doped-tio2p-si