Questions related to Nanocrystals
I have came across many research articles in which metal halide materials are dissolved in DMF or DMSO or combination of both solvents. Then the liquid is injected in isopropyl alcohol for getting halide perovskite nanocrystals. So now my question is can I use 1-propanol instead of isopropanol for getting halide perovskite nanocrystals?
Hello. I want to simulate the phase transitions of zirconia after doping with Y2O3 in the VASP package.
How and with the help of what program is it correct to create a surface from tetragonal ZrO2 nanocrystals and their structures stabilized by yttrium (ZrO2 + 3 mol.% Y2O3, ZrO2 + 8 mol.% Y2O3) for further study of water adsorption on their surface?
RRAM device has metal/insulator/metal structure, in which insulating layer acts as an active switching layer. I am looking for any correlation between the crystllite size of the active switching layer's nanoparticles with resistive switching mechanism. Does the size of Nanoparticles control the switching mechanism?
Please share some relevant articles.
I could not get any VESTA documentation nor any lectures for adding vacuum and removing boundry conditions for nanocrystals, especially defining their facets and in which directions the vacuum and periodic boundary conditions are to be added and destroyed respectively. Would be grateful if anyone provides any material related to this.
The s1 figure contains a CdSe quantum dot diagram/structure made from single unit cell of CdSe.
The s2 figure contains the powder diffraction simulation of CdSe quantum dot.
The powder diffraction simulation for a single unit cell of CdSe shows correct peaks.(s3 figure)
Here CdSe is taken as example.
The simulations are made in VESTA.
Hello everyone. I have conducted PL measurements on CsPbBr3 nanocrystals at 10 K. I observed a significant power-dependent blueshift (~50 meV) and spectral broadening as the laser power was raised from 1 W/cm^2 to 30 W/cm^2. I estimated that the range of induced carrier densities is around 10^14 to 10^15 cm^-3.
Given the typical temperature-dependent shift of the PL energy in this material, a 50 meV blue shift could be explained by an increase in temperature of around 150 K. However, I do not have any feeling for how strong the laser-induced heating should be in this material, under the given conditions.
As such, I was wondering if there was a simple way to confirm or dismiss the laser-heating argument in this situation.
Any insight or suggestions of relevant publications on this topic would be highly appreciated.
Most perovskite quantum dot/ nanoparticles are cubic while some are spherical also. What is the reason behind the cubic or spherical shape of the quantum dots? Why do they have different morphology or nucleation?
When Chitin and cellulose nanocrystals prepared using acid hydrolysis are mixed, I get two new peaks at 264 and 700. I have read some papers that indicate that these peaks correspond to aliphatic CC bonds but I not sure if that happens.
Note: these peaks do not show up on spectra when nanocrystals are are not mixed
Some papers quoted that synthesized zinc sulfate nano particles having the solubility of 100%. As per my little knowledge of nano technology, once the particle soluble, it will not sustain its size as in the nano meter range and converted to angstrom range. And so called particle not called as nano particle. So kindly clarify my query?
I am trying to synthesize TiO2 sol using the hydrolysis technique with Titanium Butoxide as a precursor, the reference as attached below.
The process is very simple as follow,
Beaker 1: 5 ml DI Water + 70 ml Ethanol @ 80°C, Stir
Beaker 2: 5 ml Ethanol + 0.075 ml H2SO4 + 0.18 ml Ti(Butoxide)
Add beaker 2 in Beaker 1. The clear solution will start turning turbid with time and after 12 hours a TiO2 sol will be formed.
However, when I add Ti(butoxide) in ethanol, it instantly changes to yellow color, which in reality should remain colorless (transparent).
Can anyone give his/her feedback and suggestions on what can be causing this issue?
I will be really thankful for the feedback.
I have encountered some studies doing this through some calculations involving FWHM values of PL bands but I couldn't figure that out. I am calculating radii by using the effective mass approximation. EMA predicts radii through bandgap energy, therefore, the output is unrealistically precise and doesn't have any error function. One of the reviewers especially asked for the size distribution calculation from the FWHM value of the PL band.
I have synthesized gelatin stabilized ZnIn2S4 nanocrystals, I have obtained XRD patterns which is different from its bulk cubic and hexagonal phases. I assume there is some shift due to nanostructure. However i couldn't assign the patterns even though I spent a lot of time looking at many literatures. Can you please assist?
Usually, I mix silicon nanocrystals with polymeric compounds to create a nanocomposite for the purpose of studying changes in the photophysicsl properties. The problem is that I am still having trouble knowing the concentration of the silicon crystals added to the mixture. I hope to help me in whatever method you think is good in determining the amount of silicon crystal in the mixture.
I am working on making nanocomposites from silicon nanocrystals and thiolate. I get a massive change in the photophysical properties of some composites. However, other composites did not show me any change in photophysical properties. I hope anyone can go more in-depth and explain how the interaction between radical thiolate and the surface of silicon nanocrystals works. Let us focus on the chemistry point of view.
I appreciate your time in answering my question.
I am trying to synthesize ZrS2 in the liquid phase based on this paper, but it does not work.
For some reason ZrO2 is formed.
Well-Defined Colloidal 2‑D Layered Transition-Metal Chalcogenide
Nanocrystals via Generalized Synthetic Protocols
I am working to detect the lifetime decay for silicon nanocrystal, so I read about the topic for more understanding.
Could you pick molicules as an example?. What will happen when a molecule is excited?.
Suppose, nanocrystals of two or more compounds are obtained in the form of stable sols. Is it possible to control aggregation between different (but mainly not the same) nanocrystals expressed as plane-selective aggregation to obtain molecule-like nanocomposite which can be used either by itself or in the form of bigger aggregates as novel metamaterials?
Hi I'm interested in analyzing transport in nanodevices. I don't clearly understand how to properly set the number of k-points sampling in transmission spectrum computations. Is it possible, given a certain nanostructure (e.g. molecule, nanocrystal...) to understand which number of them (in x,y,z directions) leads to a reasonable accuracy?
I use the Whatman 41 paper filter for filtering perovskite nanocrystals that synthesized by the Ruddlesden popper method but I have H3PO3 byproduct in the reaction equation which causes damage to the filter paper and led to defect within the synthesized crystals. what should I do to solve this issue?
If anyone knows an inexpensive anti acidic paper filter, I appreciate her/him for letting know.
I want to do compositional analysis of doped colloidal CsPbBr3 nanocrystals, by STEM-EDX.
However, even for short exposures, the electron beam induces carbon buildup on the sample, which dominates the EDX signal, and it becomes impossible to measure anything else.
Can someone indicate if and how they managed to do this type of measurement? Is the carbon buildup due to the organic ligands which are not attached to the nanocrystals? is there a simple way to remove them form the solution, to enable the measurement? Please note that I am not doing the measurement myself, so my knowledge of the technique is not very extensive.
please suggest me how make sample for XRD.
I've tried with spin coating on a glass substrate, but it didn't work.
Sampling will be done on a glass substrate.
I had made sample for nanocrystals in toluene as solvent.
#nanocrystal #perovskite #xrdsampling #MAPbI3 #colloid
I read one literature in past, which discusses selection of solubilization technology based on the melting point and log P of active pharmaceutical ingredient.
The faint content back of the mind is:
There were two graphs, Log P on X-axis and Melting point on Y-axis
 Dose is less than 100 mg, what are the zones, where you choose (1) nanonization (2) liquid filled capsules and (3) solid dispersion as solubilization enhancement technology
 If dose is greater than 100 mg, then the similar selection based on zones
COuld you please help me find this reference?
This article is really a good read.
Why are there a lot of approach to exfoliate graphene using nanocrystal cellulose rather than using microcrystal cellulose?
Is there any advantages of using nanocrystal rather than using microcrystal? If yes, what is the advantages?
also, it would be very kind if you can give the link for the supported statement/answer.
I am trying to perform Rietveld refinement with irf function for crystalline nanoparticles. During the refinement, I get "Resolution limited" message for apparent size and strain in Fullprof mic file. Why does this happen?
Please find attached an example of mic file.
Please suggest me how make sample for TEM. I have no idea how sample for TEM colloidal nanocrystal prepared. I had made sample for nanocrytals in toluene as solvent.
#Nanocrystals #Solvents #Imaging #TEM sample preparation
I have to do synthesis of W doped VO2 for which the oxalic acid dihydrate was used as reducing agent according to research paper :
i am limited to the access of oxalic acid dihydrate, Can I use oxalic acid anhydrous instead for my synthesis?
Does anyone know of any literatures where the hydrodynamic size range of cellulose nanocrystals and nanofibers would fall within? The literature I have seen indicates actual lengths and diameters, however I am going to be using a zetasizer and obviously this gives the hydrodynamic diameter so I am trying to see what size the transition from nanocrystal to nanofiber would occur.
A DSC run at a heating rate of 10K/min of nanocrystalline Y2Ti2O7 powders showed a broad exothermic peak spreading from 350 - 950 C. No such signature in the cooling curve! Can you please help us decipher this? Could crystallisation or relaxation of the nanocrystals result in such a peak? Simple crystallisation should have resulted in sharper peaks, isn't it?
Im having issues with interpreting the CV graph produced by my experiment.
Here are the details:
Metrohm spe gold disposable electrodes. Chemically cleaned then electrodeposition of palladium chloride with hcl mixture (-100 mV) to form nanocrystal on the surface - done using potentiostat. Then the electrodes are plasma cleaned with oxygen at med rf for 5 min. Then CV scans are taken using a sodium chloride and sodium phosphate buffer (25/25 mM) as a blank before dna immobilization.
Having trouble replicating data and understanding the shape of CV
Have also tried CVs without electrodeposition and getting similar shapes but with lower max current peaks
I have an HRTEM image of CuInSe2/ZnS core/shell nanocrystals where small individual dots can be seen. The size of the dot is roughly 0.2 nm. I summed up the ionic radius of Cu(+) +In(3+) 2* Se(2-) from the literature which is 0.616 nm. This means these small sized dots are the individual elements/ions as their size is lower than sum of ionic radius. So i assume that its possible to identify the individual elements (like Cu, In Se) based on the size of dots. However, i found it difficult to measure the exact size of the dots in picometer resolution using image J. So how do i do this? Is it possible?
Also is it possible to draw the crystal structure based on the position of these elements?
Ionic radius of Cu+ =140 pm, In3+ = 80 pm, Se2- = 198 pm
I have excluded the capping agents from this calculation
Thanks in advance
I want to extract an optical gap from the spectra of my work, I found a way to do that from other works " we took the absorption edge as the energy threshold at which the absorption is 2% of the total absorption. The same criterion was used previously for determining optical gaps in Si sRef. 31d and CdSe sRef. 32d nanocrystals and was found to yield good agreement with experiment. ". But I did not know how to implement this method practically Can you help me?
Is it reasonable to state that Stokes shift for core-shell nanostructures (e.g. CdSe/CdS) is smaller in comparison to bare core (e.g. CdSe)? If so, why this phenomenon occurs? Thanks in advance for your help!
A major infant formula manufacturer was forced to recall supplies from Australian supermarkets after their dry milk product was found to contain hazardous nanocrystals of Fluoride doped Hydroxyapatite.
I am currently most interested in the formation of covalently bound Fluoride attached to protein, heme centres and especially Phosphorus in food.
I have not found any literature with data for 19F NMR of milk samples containing Fluoride, either as a result of pollution, or the deliberate addition, as occurs in some human experimental locations in the UK or South America.
If anyone has access to NMR facilities, this could make the basis of a refereed paper reporting results of incremental addition of Fluoride to milk and measuring the effects of high temperature treatment as occurs in pasteurization.
31P NMR looking for 19F coupling could also prove useful.
Would anyone like to collaborate?
After quench the as-synthesised InP nanocrystals in toulene, I have tried to use methanol:crude product in ratio of 2:1 and centrifuge it with 4000rpm for 30 mins. However, the nanocrystals cannot be completely purified. Is there anyone have the experience on purifying InP in 1-octadecene? Please do drop some advices and opinion. Thank you.
I'm using a Delsa Nano (Beckman-Coulter) with a scattering (detection) angle fixed at 165 degrees to determine de size distribution of colloidal nanocrystals. Is there any problem if I choose a glass cuvette with two opposite clear sides instead of a typical one with four clear sides?
I want to synthesize CdSe nanocrystals with high temperature colloidal technique. I have some set up. But I want to buy a Temperature controller (temperature range upto 400 oC is fine) with J thermo-couple. Also I want to buy heating mantle 100 ml size. Please suggest the cheapest one and some website where I can buy?
If a nanocrystal sample is too small, for example, <5 nm. Is it possible to yield a smooth powder XRD pattern which is similar to that of an amorphous one?
how can we calculate the work function of 0-D (quantum dot or nanocrystal or molecules) and 3-D (bulk) materials using density functional theory?
I had prepared some polyhedral alloy nanocrystals by using PVP( Polyvinyl pyrrolidone ),then washed them by using water and
ethyl alcohol for several times. But a layer of PVP was found adsorbed on the nanocrystals' surface under the SEM. How to wash it completely?
What is nucleation energy? If I am making hybrid nanoparticles (metal oxide/metal), the reaction mixer contains both precursors (metal and metal oxide) and allowing to grow both nanocrystals simultaneously to make hybrid nanoparticles. Which nanoparticle can grow faster than the other? Does nucleation energy determine growth rate of nanoparticles?
How can I process the SAED TEM images to determine the crystalline planes of my nanocrystals?
I can see in the images the concentric cones of diffraction and marked atomic positions. But I do not know how to process the image to obtain the interplanar distance using the scale bar (5 1 / nm). How to use the Fourrier transform in this case?
Thank you for your attention.
I have been working on ternary and quaternary Cu based chalcogenide nanocrystals. I have measured the UV-vis-NIR absorption spectrum to calculate the band gap. From literature I came to know that the well known method to calculate the band gap is to use the (αhν)2vs hν graph. Where "α" is the absorption coefficient.
How to calculate the absorption coefficient of colloidal nanocrystals from absorption spectra?
I'm researching about Li absorption with hydroxide nanocrystal.
my hydroxide always perfect change crystal structure by absorb Li, fixed time.
but, When i refluxed 10M of LiCl long time until 2 weeks at 120'C, hydroxide didn't react 100%.
What's happening about 10M of LiCl solution when it was boiled 2 weeks?
Suppose we have a metal core surrounded by organic ligands. In that case, can a ligand act as/can be termed as a shell or is there any obvious difference between the two?
I have been asked to support an intern with the development of a ultrananocrystaline thin film MOS device. We have some already developed ultrananocrystaline thin films of Si-substrates, but i need to deposit a insulative thin film to form the MOS structure.
His project has a close deadline, so I need to find an insulative material that is easily compatible with ultrananocrystaline. My department currently has access to RF magnetron sputtering, evaporation and spin coating, I could access other resources. but the deadline is limiting my options.
I myself have developed MOS devices before using insulative Bismuth based aurivillius structures, but these require annealing at temperatures above 550OC, and do not know how the diamond films would be effected by this condition.
I am currently investigating depositing SiO2 by RF-Magnetron sputtering, but I do not know if it will need post deposition annealing. Also my RF-sputter is only equipped with a pure Ar gas capabilities, and I understand O2 partial pressures are necessary for Oxides.
If anyone can suggest any easily formed insulative thin films for use on ultrananocrystaline diamond films. I would be extremely grateful.
Recently, I have investigated vibration modes in NaGdF4 nanocrystal, and I came across of some bands in the resulting spectrum , somewhere at ~250, 300, and 360 cm-1. Somehow, I could not able to find any references to quantify and back the analysis. I would be grateful, if anyone insight me with your great knowledge related to this situation.
Thanks in advance and hope to hear from someone soon.
Could anyone please suggest some easy-to-prepare samples for DLS measurements for practice? The perfect system would be the one were you could vary the size of almost monodisperse nanoparticles, that could be comparatively easily and quickly obtained in the lab and stable enough to measure at the DLS.
A side similar question concerns the easy systems for zeta-potential measurements - the ones were you could have abs(z)>30 mV.
I have not seen any reports based on shelling of semiconductor nanocrystals with metal. In your opinion, do you think shelling a semiconductor nanocrystal(CdSe, CdS, CZTS) with metal(say Au or Ag) can improve a thin film solar cell?
Hello. I want to standardize a platform to prepare micrometric (900-1200 nm) drug nanosuspensions (nanocrystal dispersions), at my laboratory, of curcumin and other hydrophobic drugs. I have read about preparation methods and we are going to select first a bottom-up procedure since we don't have the equipment to employ a top-down approach. So, I know the main steps: dissolve hydrophobic compound in organic solvent and then mix it with an aqueous solution with a stabilizer. In my laboratory I have a bath sonicator, would that be enough to produce a narrow PDI? What's the setting and the procedure of the mixing of the phases and the stirring/sonication? Do you have any specific protocol paper about this? Thanks a lot.
I've been searching for cationic materials to stabilize a suspension of drug nanocrystals. We want to prepare curcumin nanocrystals (with a bottom up approach, probably) but we need them to be cationic for application purposes (targeting to dendritic cells - immunotherapy). I've found chitosan, cationic surfactants, and other cationic polymers to be a good choice to stabilize nano and microcrystals for this highly hydrophobic drug. Do you have any information about this topic or do you personally know which one would be better in term of prevent changes in size and polydispersity of the system? Thanks a lot!
PD: do you also think cellulose nanocrystals with curcumin are also a good option?
How to calculate the amount of strain generate in Si nanocrystals from Raman spectrum ? Is there any way to distinguish the component of strain and phonon induced Raman peak shift ?
It is a common phenomenon for most of the nanoparticles to aggregate especially when they are in dried form. For example, the morphology of freeze-dried cellulose nanocrystals was observed to be flake-like compared to the rod/needle-like morphology of never-dried cellulose nanocrystals. Several studies suggested using longer stirring time (24 h or more), tip sonication with higher amplitude considering lower concentration (1wt% or less) of nanocrystals in aqueous suspension as well as use of appropriate surfactants to achieve improved dispersion. However, still, the freeze-dried nanocrystals were found hard to re-disperse in an aqueous medium and get the similar rod/needle-like morphology (like never-dried cellulose nanocrystals).
Any thoughts/suggestions/comments/discussion on this issue????
I always get nucleation of metals onto the facets or on the defect sites or they just form separate islands. Any suggestions to achieve homogeneous nucleation?
I have seen few reports for the binding of silver ions to sulfur and forming silver sulfide when depositing silver on a semiconductor nanocrystals such as CdS, PbS, CZTS. Why? What are the factors associated with it? Is it a cation exchange process?
I'm looking for bibliographic reports that clearly stablish and explain the existence of band bending in very small nanocrystals of semiconducting materials, i.e. quantum dots. There are reports that claim there is no band bending in nanocrystlas while some others explain their results in terms of band bending. While the pictorial view would be not important, it became a bottle neck when quantitative electron transport in this materials is evaluated. I will apprecaite any deep and clear report that can pave the way. Than you very much!
When ternary compounds are synthesized, it is challenging to control the growth and crystallinity. As it gives impure phase. Is it possible that the diffusion of copper is happening? Due to which reason i am not getting pure CuCr2Se4 nanocrystals.
Following figure (see attachment of curve) is showing the time-resolved PL decay curves of Nanocrystals (red one is sample and black one is standard sample). I want to eliminate the hump, which is due to instrumental response, in the sample spectrum. But I don't know how to eliminate it. Does anyone have any idea? Any type of help will be appreciated...thanks!
I am studying the effects of ion irradiation on Iron Phosphate Glass (IPG). We have earlier reported that ion irradiation leads to stress induced crystallization (nano sized crystals) in IPG, observed from TEM. Now I am comparing the Oxygen K edges of EELS and XAS recorded from as prepared IPG and ion irradiated one. The O K-edges from the asprepared sample have comparable shapes. But EELS and XAS spectra taken from irradiated samples do not match. I understand XAS has poor spatial resolution but EELS has good spacial resolution. But the area probed by the ebeam while taking EELS is definitely more than that of the nanocrystals. Can anyone tell me what difference can we expect in between Oxygen K edges from XAS and EELS?
After conducting PL lifetime measurements on nanocrystals of different sizes (3 and 8 nm), I observe that the smaller particles have a longer lifetime than the bigger ones (especially the faster component: 3 vs 8 ns). It is unexpected, since a larger exciton band gap and a higher trap density should lead to faster recombination. Am I missing a mechanism here which could explain this phenomenon?
I have been working with oxygen reduction reaction (ORR), using Pd nanocrystals. I found that the in my case, the half-wave potential observed in the reverse scan (1.0 V vs. RHE while sweeping from more –ve potential to less negative potential) is better than in the forward scan (0.9 V vs. RHE). However when I do chronomperometry, I observe a value corresponding to the forward scan. I have not been able to find any literature justifying which scan value should be reported. Can anyone please advise or guide to the right literature. Thanks.
Respected Researchers !!! I have observed remarkably enhanced (282-fold) PL emission from Bi2Te3 nanosheets. However, its bulk counterpart being a narrow indirect bandgap semiconductor exhibits almost zero photoluminescence. Normally, SPR enhanced PL originates in the vicinity of metallic nanocrystals (The Purcell effect) .
I wonder if this pronounced signal originates solely from indirect to direct bandgap opening/transition or there might be the possibility of surface plasmon resonance (SPR) enhancement in photoluminescence from a single semiconductor ??? It should be noted that 2D nanostructure of Bi2Te3 also support SPR. Your answers would be highly appreciated.
We are investigating the hydrophobicity of modified CaCO3 nanocrystals. Is there any practical and simple way to measure the contact angle?
In theory, cobalt doped TiO2 thin film should be conductive. So, I was preparing cobalt doped TiO2 thin film on microscopic glass substrate to measure the conductivity. Samples contain different percentage of cobalt as dopant within the nanocrystals. Different rpm (500, 1000, 2000, 3000) were used to prepare film containing up to 20 layers of samples. Any idea why the samples aren't showing any conductivity. I tried to measure the resistance using two point probe.