The lubrication of Micro-Electro-Mechanical Systems (MEMS) has been a major obstacle to the micromachine industry, limiting the designs commercially available and actuating/sensing mechanisms in micro actuators/sensors to mostly non-contacting ones. MEMS are traditionally made of silicon (Si), which has very poor tribological properties. Lubrication techniques for MEMS usually involve highly expensive processes such as vapour deposition and complex hermetic packaging to ensure longer wear life. The present study proposes a novel method of locally delivering a required amount of lubricant onto a specific location on a MEMS device, extending its wear life by several orders of magnitudes. To study the feasibility of this process, a fixed amount of PFPE was delivered to a contact between two flat Si pieces which were then subjected to reciprocation sliding at an applied normal load of 0.5N and a sliding velocity of 5mms−1. Tribological properties such as coefficient of friction and wear behaviour were studied to ascertain the effectiveness of this lubrication method. The results have revealed that the current localized lubrication method is very effective in reducing the coefficient of friction and increasing wear life.

A 60 MeV Ag primary ion beam was used to generate secondary recoil ion beams of Cl, K, Ca, Sc, Ti, V, Mn and Cu in the energy range 0.1-0.6 MeV . The stopping power in the carbon absorber was measured and compared with Lindhard, Scharff and Schiott (LSS) theory, the Northcliffe and Schilling model and semiempirical estimates of Ziegler et al (1985). Data for heavier ions of Ag, I and Au from other sources was also considered in order to extend the scope of such a comparison. LSS theory was found to satisfy the data within a narrow mid-velocity range (-, where is Bohr velocity). Estimates made by Ziegler et al were seen to generally agree to within a few per cent except for energies below 0.2 MeV , where deviations as high as 25% were seen. Expected oscillations could not be discerned down to the lowest ion velocities so far attempted.

Catastrophic Dechanneling Resonance (CDR) has been used for probing important properties of Strained Layer Superlattice (SLS). We have undertaken systematic experimented and theoretical studies on strain and strain relieving mechanisms in techno logically important SLS using ion channeling methods. Here ne present the theoretical calculations on CDR for a He-4 ion bean along the (110) plane in InxGa1-xAs/GaAs superlattice using Moliere, Shell and Biersack's universal planar potentials.

We have been carrying out systematic random stopping power experiments in the low velocity region (ν0 to 5ν0, where ν0 is the Bohr velocity) using heavy ions (Z1 = 8 to 29). The objective is to supplement in a significant way the currently available scanty data in this region. In order to optimise the data collection for a variety of heavy ions, we have used our recently developed technique of adopting a twin detector in conjunction with Elastic Recoil Detection Analysis (ERDA) technique. In continuation, we now report energy losses of Si, Fe, Ni and Cu ions in carbon foil in the energy range 0.1-1.1 MeV/u. Here we are reporting experimental stopping power data for Ni ions in the velocity region of 0.1-0.6 MeV/u. Most of the experimental data have an error of around 6%. Comparison of the now available data have been made with existing theoretical and semiempirical models.

Abstract Stopping powers for ions of O, Cl, Sc, Ti, Cr, Mn, Fe and Cu in the energy range 0.2–1.0 MeV/n have been measured in carbon foils using the elastic recoil ion technique and a twin detector system. Very heavy ions of Gold and Iodine of energy around 100 MeV have been employed to generate the various recoil ions using pure thin (≈ 1000A) elemental/compound targets. The data have an overall average accuracy of 6%. The stopping power for Sc, Mn and Fe ions in the energy region 0.2–1.0 MeV/n as well as those for Ti and Cu ions in the energy region below 0.45 MeV/n are perhaps the first such measurements. The limitations of LSS theory even within the range of its applicability has been demonstrated. Varelas and Biersack estimates agree well in the region of their applicability lying above the ion velocity limit set for LSS theory. Northcliffe and Schilling predictions as well as the TRIM estimates provide the best fit with data. However, one does notice variations upto 25% for some ions at lower energi...

The possibility of pions and muons being used as probe particles for defects studies in materials research has been investigated for the past thirty years or so. We discuss here the similarities of π+ and µ+ with positrons and tritons so that they can be treated as light hydrogen isotopes. Incident pions occupy a lattice site (substitutional or interstitial) and then decay into muons of energy 4.12 MeV which undergo channeling effects. The scattering cross-section of pions in tantalum single crystal with oxygen impurities has been evaluated applying Born approximation and using a double screened potential. The same calculation is applicable for muons after making some relativistic corrections. This model should also be applicable in various other situations where dechanneling by heavy ion impurities existing in multiple charge states takes place in an otherwise perfect single crystal.

A simple double screening model is used to calculate the interaction potential between an energetic channeled mu(+) and an impurity (O) in an otherwise perfect single crystal (Ta). The twofold screening of the nuclear charge of the impurity is first due to the atomic electrons and second due to conduction electrons of the host crystal (Ta). Using this potential the dechanneling cross-section of muons due to the oxygen impurity in the lattice of Ta along various planes is evaluated. Three charge states of the oxygen impurity are considered and the corresponding dechanneling cross-sections are predicted.

Stopping powers for O and Ti ions were measured in a mylar foil 2 μm thick. The choice of the foil was made because of its wide application in elastic recoil detection analysis experiments and thin windows for gaseous detectors. As a new approach, recoil ions produced in heavy ion scattering were utilized for (dE/dx) measurements. The energy loss of the recoil ions was measured by keeping two surface barrier detectors, with and without the mylar foil, at the same recoil angle, with their gains matched with pulsers before the experiment. Different energies of the secondary beam could be selected by changing the detection angle. Also, various species of secondary ions could be obtained by merely changing the target. We demonstrate here our new technique and some of the results obtained.