I have synthesized SnO2 nanoparticles and found the average size 14 nm using Scherrer Formula, but I want to synthesize nanoparticles of about 5 nm in size. The detail of experimental procedure is mentioned below:
For 0.1M solution, 3.50 gm of Tin chloride (SnCl2.5H2O) was added in 100 ml ethanol in a beaker. The solution was set at stirring for 10 min on magnetic stirrer at 100 C at the rate of 550 rpm. 2ml acetic acid was then added drop by drop. After which, 5ml ammonia solution (NH4OH) was added drop by drop in the solution to increase the pH value of the solution which results in nucleation (the basic phenomena of precipitate formation in chemical co precipitation). When pH value reached at 5, precipitates were found in the solution and its colour become white. The value of pH was set at 5 and the solution was left on stirring for 1 hour at 550 rpm at 100 C◦.After 1 hour, this the solution was aged at room temperature for 1 hour. Then it was centrifuged and washed with distilled water 3 times. The centrifugation rate was 3000 rpm and time was 3 minutes each time. Then the solution has been kept in an oven for drying overnight at 80 C◦. Next day the dried product is grinded in powder form. Grinded powder then kept in furnace at 600C for 5 hours.
Hi Muhammed,
You might implement high energy sonication which is expected to break the particles into smaller fragments.
You are working on oxide nanoparticles, and I would think that you can play with 2 types of methods.
One should be physically "ultrasonic". If it is possible, please find a ultrasonic source and effort to your solution during reaction. The turburlence occurr from the strong ultrasonic might dispense the particles from each other. We are doing this process for ZnO and MnO colloids, and it works.
On the other hand, you can play chemically with the surfactants, with their concentrations and with their structure. My tips are that the higher concentration the smaller particles you should have, but please pay attention to pH value (lower pH value might against the formation of your particles). You are using acetic acid, which is quite well hydrophilic and they would attach to the surface of the forming particles, hence create an electronic pushing force between the particles, while the organic form might release the acidity of the solution. Please try with other organic acid, such as malic acid, citric acid or higher such as pyruvic acid.
Best luck !
Thanks a lot.
- Should I ultrasonicate the stock solution before centrifugation ?
- You quoted that "please pay attention to pH value (lower pH value might against the formation of your particles)." What do you mean by this, at low pH value particle size will be large? or you want to say that at low pH quantity of particles will be less? I know that as we increase the pH value of the solution, the precipitate formation also increases.
Dear Ali,
You could sonicate the stock solution, but please put them into ice-bath, because the ultrasonic might increase the temparature very fast. However, i would rather ultrasonicate only during the reaction (adding amonium water).
You can see that lower pH might create acidic environment and your colloids are oxide. Lower pH solution (lower than 3) would dissolve your colloids. However, in some cases, pH value lower than 5 might slow down the reaction rate and make the size of the particles becomes smaller.
Thanks. I got it.
- Do you have any idea about the effect of pH value on the activity of nanoparticles?
- Do you know about effect of stirring time,temperature and rpm on particle size?
- You mean by ultrasonication during reaction is that I should ultrasoicate and add ammonia solution simultaneously ?
As I read that you are synthesizing SnO2 on graphene and would rather to study the dielectrical properties of the materials, I assume that the "activity" that you mentioned here is the "dieclectric" ?
It is a very complicated question when we are talking about the hydrodynamic problem when using stirring in order to effect the size of the particles. I would prepare my sample while stirring when I try to make the solution being homogenous constantly. The temperature then would be a very good agent that effect on particles sizes. As physics point of view, when you try to increase the temperature, the reaction rate increase consequently; hence might increase the creation rate of oxide (notedly the reactionrate depends on the temperature by Arrhenius formula - exponentially), thus makes the particles size increase. However, I prefer to create oxide particles at about 60-80oC (experiently in this tem. the oxide formation effeciency become optimic).
Yes, i do think about that you can ultrasonicate during reaction. Please note that ultrasonic make the size of the particles become smaller, but we could not controll the turbulence during the ultrasonic, that why it is very hard to controll the size distribution of the partilces (normally impossible).
We also used ultrasonic for synthesis PbS during wet-chemical method, and mostly without any surfactants the size of the particles become smaller than 10 nm, and very dispersive.
In your case, if you try to stick the particles on graphene surface during reaction, I would rather not to use ultrasonic !
Thanks a lot for your guidance.
Yes, its dielectric. SnO2-Graphene Nanocomposites exhibit improved dielectric properties. These nanocomposites have wide range of applications in Li-ion batteries and supercapacitors.
I am not going to stick particles on graphene during the reaction rather I suppose to load them on graphene by some other chemical route.
Sintering temperature should be low 400-450 and for less time.
See the this paper.
http://www.electrochemsci.org/papers/vol9/90100081.pdf
http://pubs.rsc.org/en/content/articlepdf/2014/CE/C3CE42659A
According to my experience the firing temperature is the main factor to control the grain size. If you fire the xerogel at 300 or 400 C the grain size will be smaller. However, you will have to fire much longer time in order to terminate the oxide formation process. Lower times is important only to prevent recrystallization at higher temperatures.
By adding HCl in the reaction also helps to reduce the size of the particles, because it controls the growth rate and suppress the hydrolysis process. This leads to the formation of SnO2 phase and gives the reduced particle size
I tried to made SnO2 from SnCl.2H2O and NaOH but the solution becomes black? Is there step of color changing of SnO2 process??
I want to know the use of acetic acid here. And is this stannous or stannic chloride?
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