Charu Lata Dube

Growth of Si0.75Ge0.25 alloy nanowires in a separated H-field by microwave processing

This paper presents a rapid and novel technique of growing nanowires of Si0.75Ge0.25 alloy at 900 °C in less than 10 min by processing the constituents in a TE011 single mode cylindrical resonant cavity, operated at 2.45 GHz and ∼300 W. The microstructural, crystal structural, and x-ray photoelectron spectroscopic studies of the nanowires have been carried out to establish their dimensions, crystallographic structure, and composition, respectively. It is proposed that the growth of nanowires is due to electromagnetic field assisted morphological transformation.

Synthesis of Silicon Nanowires Using Microwave Energy for Optical Devices

ABSTRACT In the present work, silicon nanowires have been grown in a TE011 single-mode cylindrical microwave resonant cavity operating at 2.45 GHz. The microstructural, structural, elemental, and room temperature photoluminiscence studies have been carried out of the grown nanowires. The wires are encapsulated by an ultrathin layer of silicon oxynitride. The observed strong visile photoluminescenc is ascribed to ballistic transport and radiative recombination (at Si/SiON interface) of the carriers generated due to light absorption.

Microwave processing of ZnO based dilute magnetic semiconductors

In the present work, polycrystalline ferromagnetic Zn0.95Co0.05O samples have been synthesized in a TM011 single mode cylindrical microwave resonant cavity operating at 2.45 GHz. The synthesized specimen is analyzed for its crystallographic and electronic structure along with magnetic and electron transport properties. The X-ray diffractogram and photoelectron spectroscopy of Zn0.95Co0.05O establish the incorporation of cobalt atoms into ZnO lattice. The room temperature magnetization study confirms the ferromagnetic ordering in the microwave processed highly resistive samples; which can be attributed to bound magnetic polarons model.

Synthesis of Si‐Ge Alloys in Microwave H‐field

Polycrystalline Si0.9Ge0.1 alloy has been synthesized by microwave processing in a H011 single mode cylindrical resonant cavity (2.45 GHz, 450 W) at 950°C in about 4 minutes. The X‐ray diffractograms of mixture recorded before and after the exposure to microwaves confirm the formation of Si‐Ge alloy. IR absorption spectrum also confirms Si‐Ge alloy formation along with the presence of silicon and germanium oxide in the sample. Band gap estimated from the electrical conductivity versus temperature measurement comes ∼1.08 eV. With an increase in heating time from 4 to 12 minutes, the grain size marginally increases from ∼94 to 104 nm.

Microwave synthesis and mechanical characterization of functionally graded material for applications in fusion devices

Functionally graded tungsten–copper bimetallic compact with fine microstructure and good mechanical property has been synthesized by employing microwave heating method at a temperature of 800 °C and in a short processing time of 30 min. Scanning electron microscopy and energy dispersive X-ray analysis revealed the graded structure of synthesized sample. The fine microstructure of tungsten in each layer is caused by arrested grain growth because of the short sintering time. The overall relative density of the W/Cu functionally graded sample has reached 87% of the theoretical density. Vickers microhardness measurements, across the length of a compact, show increase in hardness value of the sample with the increase in tungsten content. The experimental hardness values match well with the theoretically calculated hardness values.

Rapid decrystallization of a polycrystalline hard ferrite by separated H-field microwave processing

Microwave (MW) processing of materials has recently emerged as a powerful and potential green technique. In addition to being volumetric and fast, the MW heating of a sample can modify the structure and microstructure (e.g. decrystallization, new phase formation and growth of nanowires), and is thus capable of tailoring a material to yield desired properties.