1. Introduction

1.1 Purpose of the study
Zinc sulfate crystals possesses wide range of applications in the field of telecommunication, solar systems for solar energy storage, coagulation bath for rayon & optical information storage devices and even in many of our daily products. (Saha & Podder, 2011) Crystals are used in many appliances because of their electrical and magnetic properties. They are used for radio sound waves and television light waves. Hence, the presence of a magnetic field on the rate of growth of the zinc sulfate crystals is being investigated, as we particularly want to know how the crystal’s growth can be affected by the various changes in its surroundings.

1.2 Background Research  
This literature review is mainly focused on the effects of magnetic field on the crystallization from solutions. The first article focuses on the influence of the magnetic field on the crystallization form of calcium carbonate with a magnetic field.  CaCO crystals were grown from tap water and model water both with and withou
Figure 1

t a magnetic field.  Experiments were performed in parallel runs. One of the runs was treated with a magnetic field and the other was not. For the magnetic treatment, an applied DC field of between 0.5 and 1.3 T used. Results from the X-ray analysis showed that there was a difference in the amount of the three crystallographic forms of CaCO³ if the model water was treated with a magnetic field. Fig. 1 shows the X-ray diffraction spectra of the crystals obtained from magnetically treated and untreated samples. Particles crystallized
in the absence of the magnetic field were found to be in the well-crystallised calcite phase.The results of the diffraction analysis show:
- significantly more aragonite in the magnetically treated sample;
- relatively high proportions of vaterite in both samples.

Vaterite is a metastable crystal modification of calcium carbonate that often precipitates first, but usually transforms quickly to calcite.
Figure 2
Therefore, it has been proven that the existence, and preferential growth, of the crystal
form does not cause scaling, or at least not to such an extent as calcite. (Kobe, Dražić, McGuiness & Stražišar, 2001)

The second article is on the influences of high magnetic field on glycine crystal growth. The effects of a horizontal magnetic field of 8 T on glycine a-form crystals, which is one of the typical amino acid crystals, and its growth rate, in order to examine the effects of horizontal magnetic field were investigated. A horizontal magnetic field was applied using a superconducting magnet on all the solutions and seed crystals were prepared from super saturated glycine solution. Crystal growth rates in the absence and presence of a magnetic field of 8 T were obtained using the same crystal, since the absolute growth rate varies slightly from crystal to crystal. The magnetic field was changed from 0 to 8 T or 8 to 0 T during the crystal growth, as it takes 18 min to change the field intensity. Fig. 2 shows photographs of a-form glycine crystals in the absence and presence of a magnetic field of 8 T. In both cases, the growth rate is decreased by about 20% by applying a magnetic field of 8 T. Thus, it is shown that a horizontal field affects not only crystal orientation but also crystal growth rate. (Sueda, Katsuki, Fujiwara & Tanimoto, 2006)

In the third article the effect of magnetic field on the crystallization of diamagnetic zinc sulfate was investigated in a series of controlled batch cooling experiments. When the zinc sulfate solutions were exposed to magnetic fields of different intensities, up to a maximum of 0.7T, a clear influence of magnetic field on its crystallization parameters was found. There was observed to be an increase in experimental saturation temperature, an increase in average growth rate about 41% and the average crystal size was 38% higher, whereas the metastable zone width decreased by 43% compared to the control that was set up. However, there was no significant change in these parameters when the magnetic field intensity was increased from 0.3 to 0.7 T. Hence, it is probable that the magnetic field effect reaches saturation at some value below 0.3 T. (Freitas, Landgraf, Seckler & Giulietti, 1999)

1.3 Research Question
What is the effect of the presence of a magnetic field on the growth of zinc sulfate crystals?

1.4 Hypothesis
The presence of a magnetic field will increase the rate of growth of the zinc sulfate crystals.

1.4.1 Independent variable(s)
Presence of a magnetic field

1.4.2 Dependent variable
The size of crystals, the mass of crystals grown, the visible structure of the crystals grown

1.4.3 Constants
  • Humidity of the surrounding air
  • Concentration of zinc sulfate used
  • Total volume of zinc sulfate solution used
  • Temperature of the surrounding air
  • Saturation of solution
  • The length of time for both solutions to grow crystals

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