1. Introduction
The optical and electronic properties of materials change drastically
due to the quantum confinement of the charge carriers
within the particle. SrO, an important wide band gap metal oxide
(MOX) has attracted much attention. Jose et al. [1] reported the
glass system of SrO for new broadband Raman gain media. Due
to the inherent high-energy phonons in silicate-based glasses,
usable rare-earth ions, which are optically active for optical ampli-
fication, are limited in silicate-based fibers. Because fluoride and
heavy metal oxide glasses have low energy phonons and many
rare-earth ions are optically active in them, these glasses have been
studied as rare-earth hosts to expand amplification bandwidth in
wavelength division multiplexing (WDM) systems [2]. There has
been several method for the synthesis of MOX by low-temperature
routes to obtain relatively homogeneous and small-sized grains.
These methods include chemical precipitation, hydrothermal reaction
and the sol gel method. Here we discuss chemical precipitation
method for the synthesis of SrO QDs [3].
MOX nanoparticles can exhibit unique physical and chemical
properties due to their limited size and a high density of corner
or edge surface sites. Particle size is expected to influence three
important groups of basic properties in any material. The first
one comprises the structural characteristics, namely the lattice
symmetry and cell parameters [4]. Bulk oxides are usually robust
and stable systems with well-defined crystallographic structures.
However, the growing importance of surface free energy and stress
with decreasing particle size must be considered: changes in thermodynamic
stability associated with size can induce modification
of cell parameters and/or structural transformations [5] and in extreme
cases the nanoparticle can disappear due to interactions
with its surrounding environment and a high surface free energy
[6]. Although, SrO is a dangerously radioactive isotope, it is a useful
by-product of nuclear reactors from which spent fuel is extracted.
Its high-energy radiation can be used to generate an electric current,
and for this reason it can be used in space vehicles, remote
weather stations and navigation buoys [7].
The optical conduction is one of the fundamental properties of
metal oxides and can be experimentally obtained from reflectivity
and absorption measurements. Due to quantum-size confinement,
absorption of light becomes both discrete-like and size-dependent.
In nano-crystalline semiconductors, both linear (one exciton per
particle) and non-linear optical (multiple excitons) properties arise
as a result of transitions between electron and hole discrete or
quantized electronic levels. In the first case, depending on the relationship
between the radius of the nanoparticle (R) and the Bohr
radius (RB) of the bulk exciton, the quantum confinement effect
can be divided into three categories; weak, intermediate and
strong confinement regimes, which correspond to R RB, R RB,
and R RB, respectively [8]. The effective mass theory (EMA) is
the most elegant and general theory to explain the size dependence
of the optical properties of nanometer semiconductors.
In the present work, SrO QDs are synthesized by one pot chemical
precipitation method. The direct and indirect band gaps of QDs
are determined through UV–VIS analysis. The quantum dot radius
is computed from hyperbolic band model (HBM) using UV–VIS