Spinel compounds are of continuing interest because they exhibit a wide range of novel and manipulable applications of value in electronic, magnetic, catalytic, photonic, and structural properties. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Thus, the crystal structures, phase equilibria and composition ranges of materials that form both normal and inverse spinels have been studied extensively, frequently to optimize specific properties. Properties optimization drives continuing efforts to produce new materials, extend phase fields and improve homogeneity. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] This in turn provides the impetus to develop new synthesis and processing approaches.We recently demonstrated that liquid-feed flame spray pyrolysis, LF-FSP provides access to a new hexagonal phase in nano-Y 3 Al 5 O 12 and a general route to nano-a-Al 2 O 3 (30-90 nm). [19,20] We now find that LF-FSP offers a general route to common phase pure spinel nanopowders, (MO) 1 À x (Al 2 O 3 ) x M ¼ Mg, Ni, Co, Zn, and (MgO) 0.6 (Fe 2 O 3 ) 0.4 , with compositions previously unknown thereby greatly extending their phase fields. [1,2,[13][14][15][16][17][18][19]21] Given their significant academic and commercial import, access to entirely new compositions in spinel phase materials could expand the horizons of spinel materials' properties greatly. In LF-FSP, alcohol solutions of metalloorganics [e.g. Al(OCH 2 CH 2 ) 3 N (alumatrane) and Mg(2,4-pentanedionato) 2 ] are aerosolized with O 2 into a quartz chamber (1.5 m) and combusted [22] at 1500 8-2000 8C. Quenching to %300 8C in 30 ms over %1 m gives dispersible nanopowders often with novel phases as noted above [19,20] and for example a one step synthesis of the difficult to produce Na þ doped b 00 -alumina. [22] In an effort to dope nano-a-Al 2 O 3 with MgO to prevent grain growth during sintering, [23,24] LF-FSP was used to combinatorially produce MgO doped nano-d-Al 2 O 3 as a prelude to a second pass through the LF-FSP system to produce Mg doped a-Al 2 O 3 .[24] Figure 1 shows XRDs for LF-FSP generated (MgO) x (Al 2 O 3 ) 1 À x nanopowders where x ¼ 0-0.20. Exact compositions were confirmed by XRF analyses.[22]As substantiated by numerous studies, [9][10][11][12][13][14][15][25][26][27] . In some instances, as in the nickel system, [28] the materials are mostly the inverse spinel.The reported (NiO) x (Al 2 O 3 ) 1 À x phase diagram shows a spinel phase field in the alumina rich region that extends from x ¼ 0.50 to 0.60 at 1500 8C but broadens to %0.68 at temperatures near 2000 8C.[29] Thus, our observation of a pure spinel phase at x ¼ 0.78 greatly extends this phase field. The resulting spinel is very stable, resisting transformation to the phase diagram composition even on heating for 10 h at 1150 8C, Figure 2. Similar observations are made for the (CoO) x (Al 2 O 3 ) 1 À x system, where at 1500 8C the published phase diagram in the alumina rich region extends to 45 mol % (x ¼ 0.45) but expands to 78 mol % near 1950 8C. [31,32] We observe...

We present a newly devised technique, the dynamic layer-by-layer (LbL) deposition method, that is designed to take advantage of the LbL deposition method and fluidic devices. Polyelectrolyte solutions are sequentially injected through the fluidic LbL deposition device to quickly build well-defined multilayer films on a selected region with a linear increase in the material deposited. Multilayer film fabrication by this new method on a specific region was proven to be fast and effective. The effects on film quality of the processing parameters such as concentration of polyelectrolytes, flow rate, and contact time were investigated. A half-tethered self-standing film on a substrate was fabricated to demonstrate the effectiveness and the region-selective deposition capability of the devised dynamic LbL deposition method.

Measurements of diamagnetic flux in Aditya tokamak for different discharge conditions are reported for the first time. The measured diamagnetic flux in a typical discharge is less than 0.6 mWb and therefore it has required careful compensation for various kinds of pick-ups. The hardware and software compensations employed in this measurement are described. We introduce compensation of a pick-up due to plasma current of less than 20 kA in short duration discharges, in which plasma pressure gradient is supposed to be negligible. The flux measurement during radio frequency heating is also presented in order to validate compensation.

A steady state superconducting tokamak (SST-1) has been commissioned after the successful experimental and engineering validations of its critical sub-systems. During the 'engineering validation phase' of SST-1; the cryostat was demonstrated to be leak-tight in all operational scenarios, 80 K thermal shields were demonstrated to be uniformly cooled without regions of 'thermal runaway and hot spots', the superconducting toroidal field magnets were demonstrated to be cooled to their nominal operational conditions and charged up to 1.5 T of the field at the major radius. The engineering validations further demonstrated the assembled SST-1 machine shell to be a graded, stress-strain optimized and distributed thermo-mechanical device, apart from the integrated vacuum vessel being validated to be UHV compatible etc. Subsequently, 'field error components' in SST-1 were measured to be acceptable towards plasma discharges. A successful breakdown in SST-1 was obtained in SST-1 in June 2013 assisted with electron cyclotron pre-ionization in the second harmonic mode, thus marking the 'first plasma' in SST-1 and the arrival of SST-1 into the league of contemporary steady state devices.Subsequent to the first plasma, successful repeatable plasma start-ups with E ∼ 0.4 V m −1 , and plasma current in excess of 70 kA for 400 ms assisted with electron cyclotron heating pre-ionization at a field of 1.5 T have so far been achieved in SST-1. Lengthening the plasma pulse duration with lower hybrid current drive, confinement and transport in SST-1 plasmas and magnetohydrodynamic activities typical to large aspect ratio SST-1 discharges are presently being investigated in SST-1. In parallel, SST-1 has uniquely demonstrated reliable cryo-stable high field operation of superconducting TF magnets in the two-phase cooling mode, operation of vapour-cooled current leads with cold gas instead of liquid helium and an order less dc joint resistance in superconducting magnet winding packs with high transport currents. In parallel, SST-1 is also continually getting up-graded with first wall integration, superconducting central solenoid installation and over-loaded MgB 2 -brass based current leads etc. Phase-1 of SST-1 up-gradation is scheduled by the first half of 2015, after which long pulse plasma experiments in both circular and elongated configurations have been planned in SST-1.

The influence of background plasma poloidal rotation on the rotation frequency of the m/n = 2/1 drift tearing mode (DTM) has been studied in ADITYA-U tokamak. The poloidal rotation velocity of the background plasma in the ion diamagnetic direction is increased or decreased by inducing an outward or inward radial electric field, respectively, through a biased-electrode placed in the edge region of the plasma. The rotation frequency of the preexisting drift tearing mode, rotating in the electron diamagnetic direction, concomitantly decreased or increased with the application of bias depending on its polarity. The positive-bias increases the background plasma rotation in the ion-diamagnetic direction from its pre-bias value, hence decreasing the DTM rotation frequency, whereas the negative bias reduces the plasma rotation velocity in the ion-diamagnetic direction, hence increasing the mode rotation. In addition to that, a short gas puff introduced during the positive and negative bias pulse further reduces the mode frequency, however, with different amplitudes in different bias-polarities. These observations suggest that the background plasma rotation contributes significantly toward the rotation of DTMs, and the rotation frequency of the magnetohydrodynamic modes can be modified by varying the poloidal rotation of the background plasma and/or the diamagnetic drift frequency.