rus
Issue #5/2024
E.V.Panfilova, V.A.Diubanov, A.R.Ibragimov, D.Yu.Shramko
LABORATORY COMPLEX FOR OBTAINING COLLOIDAL PHOTIC-CRYSTAL STRUCTURES. PART 2
LABORATORY COMPLEX FOR OBTAINING COLLOIDAL PHOTIC-CRYSTAL STRUCTURES. PART 2
DOI: https://doi.org/10.22184/1993-8578.2024.17.5.268.275
Colloidal photonic crystal structures are a promising material for nanoengineering. The goal of the work was to create a set of scalable equipment for the synthesis of monodisperse colloidal particles and the production of superlattices from them. The authors presented a description of the kit, the results of a study of the structures and formulated recommendations for the design of equipment and the implementation of technological processes.
Colloidal photonic crystal structures are a promising material for nanoengineering. The goal of the work was to create a set of scalable equipment for the synthesis of monodisperse colloidal particles and the production of superlattices from them. The authors presented a description of the kit, the results of a study of the structures and formulated recommendations for the design of equipment and the implementation of technological processes.
Теги: colloidal photonic crystal structures nanoengineering photonics superlattices коллоидные фотонно-кристаллические структуры наноинженерия сверхрешетки фотоника
EQUIPMENT AND TOOLING
The operation of substrate cleaning is implemented in an ultrasonic bath Skymen JP-010T (Skymen, China) in acetone, alcohol and deionised water sequentially. The main task of pretreatment of colloidal solution is to increase its monodispersity. It is solved by separating the solution into fractions in centrifuge ELMI CM-6MT (Elmi, Latvia), the maximum centrifuge speed is 3500 rpm.
In order to obtain SDPs of a given size, a solution synthesis scheme was proposed, in which the main variable factor is the concentration of ammonia, while the other factors considered earlier are stabilised. The laboratory bench corresponding to this scheme includes a 4-place magnetic stirrer for carrying out two parallel processes, a thermostat providing maintenance of temperatures in the range of +10...+150 °С, equipment for keeping accurate positioning of flasks, digital sensors of temperature, electrical conductivity and hydrogen indicator pH, allowing to analyse all stages of the process of particle formation. Fig.5 shows the mock-up of the laboratory bench, Fig.6 shows the assembled bench.
Self-assembly of colloidal crystals in the laboratory complex is realised on the centrifuge ELMI CM-6MT as well as two original installations.
The vertical drawing unit from colloidal solution was developed for the eponymous method of colloidal layers production (Fig.3a). It represents a three-part assembled body. The lower part contains a massive platform mounted on disc rubber vibration supports. The central part of the structure is a working chamber, the walls of which are made of transparent organic glass 3 mm thick, which allows both to monitor the drawing process and the result obtained, and to protect from external influences (e.g., air flows). A container with colloidal solution is installed in the working chamber, into which the substrate is immersed by a special mechanism. The immersion mechanism itself is located in the upper part of the unit, where the entire control system is also located. The mechanism is a 0.9° stepper motor connected to the control system via a special driver that divides each step into 256 microsteps, ensuring minimum linear movement per step. A non-stretchable belt is attached to the output shaft of the stepper motor, which limits the rotation of the substrate fixed in the substrate holder around its axis. The substrate holder in its turn can change substrate inclination relative to the pulling axis by means of a special rotary mechanism. The whole mechanism is controlled by the Arduino Mega microcontroller, values of speed and direction of pulling, length of the substrate are entered from the keyboard and LCD display on the upper part of the case. The whole mechanism allows smooth movement at speeds ranging from 0.01 mm/min to 10 mm/min.
The universal setup for obtaining colloidal structures (Fig.8) was developed to support the electrophoresis (Fig.3b), vertical deposition (Fig.3c) and Langmuir Blodgett (Fig.3d) methods. The last two methods can be realised under conditions of their support by electrophoresis, which provides the above described complex effect on the self-assembly process with automatic regulation of the applied potential difference and the possibility of applying a pulse voltage with a value from 1 to 20 V. In the installation is provided maintenance of the solution temperature during the process in the range from 12 to 55 °C. The solution pumping rate is adjustable in the range from 0.2 to 12.2 ml/min. Control of the hydrogen index of the solution is developed.
To control the unit, a software developed for Windows PC with a user-friendly interface is used (Fig.9). Connection to the unit is made using Bluetooth technology. The user interface on the PC allows to perform:
user authorisation with control of access levels;
setting of internal parameters of the unit;
error control;
viewing of parameter graphs for the performed processes with division by user identifiers;
control of solution pH;
smooth regulation of voltage, pumping speed and temperature;
control of process parameters on the screen in real time mode.
Heat treatment of polystyrene structures is implemented in a UT-4630V vacuum drying cabinet (ULAB, Russia). The process of adjusting the size and packing density of microspheres is carried out in the Sirus T2 Trion plasma chemical etching unit (RIE) (Trion Technology, USA).
RESULTS AND DISCUSSION
The proposed scheme of SDP synthesis allows to obtain microspheres with diameters from 161 to 271 nm with a standard deviation of particle sizes from 12 to 3%, respectively. Varying the size of the obtained particles is carried out by changing composition of the reaction mixture and duration of the process. Fig.10 shows the dependence of the size of formed SDPs on the amount of ammonia in the mixture.
Spectrophotometric study, AFM and SEM control demonstrate the photonic-crystalline nature of the samples. Fig.10 shows SEM images of colloidal films after their preparation, heat treatment and plasma etching. The formation of "bridges" during film hardening and transformation of the structure into a loosely packed crystal during its plasma treatment can be clearly seen. Fig.13 shows the reflection spectra of films obtained by centrifugation and vertical deposition methods.
Control of solution parameters in combination with process parameters allows to form ordered colloidal photonic-crystalline films with controlled number of layers (Fig.12), including monolayer.
Visual inspection of the formed structures reveals pronounced opalescence, which confirms that their structure corresponds to the photonic-crystal superlattice.
CONCLUSIONS
The laboratory complex for production of colloidal photonic-crystalline structures, firstly, makes it possible to produce high-quality samples with reproducible properties, secondly, it provides an opportunity to carry out research into the process of nanostructure formation at a modern and methodologically competent level, thirdly, it is a source of materials for improving the methodological and metrological bases of research, fourthly, it is used in the educational process to develop and consolidate practical skills and competences in the field of nanostructures, fourthly, it is used in the educational process to develop and consolidate practical skills and competences in the field of nanostructures.
The elaboration of theoretical, hardware and software base in the development of the complex can serve as a basis for the design of real production taking into account the main aspects and key influencing factors. Each part of the complex can be scaled up to ensure the required productivity of production of products based on colloidal photonic-crystalline films.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
The operation of substrate cleaning is implemented in an ultrasonic bath Skymen JP-010T (Skymen, China) in acetone, alcohol and deionised water sequentially. The main task of pretreatment of colloidal solution is to increase its monodispersity. It is solved by separating the solution into fractions in centrifuge ELMI CM-6MT (Elmi, Latvia), the maximum centrifuge speed is 3500 rpm.
In order to obtain SDPs of a given size, a solution synthesis scheme was proposed, in which the main variable factor is the concentration of ammonia, while the other factors considered earlier are stabilised. The laboratory bench corresponding to this scheme includes a 4-place magnetic stirrer for carrying out two parallel processes, a thermostat providing maintenance of temperatures in the range of +10...+150 °С, equipment for keeping accurate positioning of flasks, digital sensors of temperature, electrical conductivity and hydrogen indicator pH, allowing to analyse all stages of the process of particle formation. Fig.5 shows the mock-up of the laboratory bench, Fig.6 shows the assembled bench.
Self-assembly of colloidal crystals in the laboratory complex is realised on the centrifuge ELMI CM-6MT as well as two original installations.
The vertical drawing unit from colloidal solution was developed for the eponymous method of colloidal layers production (Fig.3a). It represents a three-part assembled body. The lower part contains a massive platform mounted on disc rubber vibration supports. The central part of the structure is a working chamber, the walls of which are made of transparent organic glass 3 mm thick, which allows both to monitor the drawing process and the result obtained, and to protect from external influences (e.g., air flows). A container with colloidal solution is installed in the working chamber, into which the substrate is immersed by a special mechanism. The immersion mechanism itself is located in the upper part of the unit, where the entire control system is also located. The mechanism is a 0.9° stepper motor connected to the control system via a special driver that divides each step into 256 microsteps, ensuring minimum linear movement per step. A non-stretchable belt is attached to the output shaft of the stepper motor, which limits the rotation of the substrate fixed in the substrate holder around its axis. The substrate holder in its turn can change substrate inclination relative to the pulling axis by means of a special rotary mechanism. The whole mechanism is controlled by the Arduino Mega microcontroller, values of speed and direction of pulling, length of the substrate are entered from the keyboard and LCD display on the upper part of the case. The whole mechanism allows smooth movement at speeds ranging from 0.01 mm/min to 10 mm/min.
The universal setup for obtaining colloidal structures (Fig.8) was developed to support the electrophoresis (Fig.3b), vertical deposition (Fig.3c) and Langmuir Blodgett (Fig.3d) methods. The last two methods can be realised under conditions of their support by electrophoresis, which provides the above described complex effect on the self-assembly process with automatic regulation of the applied potential difference and the possibility of applying a pulse voltage with a value from 1 to 20 V. In the installation is provided maintenance of the solution temperature during the process in the range from 12 to 55 °C. The solution pumping rate is adjustable in the range from 0.2 to 12.2 ml/min. Control of the hydrogen index of the solution is developed.
To control the unit, a software developed for Windows PC with a user-friendly interface is used (Fig.9). Connection to the unit is made using Bluetooth technology. The user interface on the PC allows to perform:
user authorisation with control of access levels;
setting of internal parameters of the unit;
error control;
viewing of parameter graphs for the performed processes with division by user identifiers;
control of solution pH;
smooth regulation of voltage, pumping speed and temperature;
control of process parameters on the screen in real time mode.
Heat treatment of polystyrene structures is implemented in a UT-4630V vacuum drying cabinet (ULAB, Russia). The process of adjusting the size and packing density of microspheres is carried out in the Sirus T2 Trion plasma chemical etching unit (RIE) (Trion Technology, USA).
RESULTS AND DISCUSSION
The proposed scheme of SDP synthesis allows to obtain microspheres with diameters from 161 to 271 nm with a standard deviation of particle sizes from 12 to 3%, respectively. Varying the size of the obtained particles is carried out by changing composition of the reaction mixture and duration of the process. Fig.10 shows the dependence of the size of formed SDPs on the amount of ammonia in the mixture.
Spectrophotometric study, AFM and SEM control demonstrate the photonic-crystalline nature of the samples. Fig.10 shows SEM images of colloidal films after their preparation, heat treatment and plasma etching. The formation of "bridges" during film hardening and transformation of the structure into a loosely packed crystal during its plasma treatment can be clearly seen. Fig.13 shows the reflection spectra of films obtained by centrifugation and vertical deposition methods.
Control of solution parameters in combination with process parameters allows to form ordered colloidal photonic-crystalline films with controlled number of layers (Fig.12), including monolayer.
Visual inspection of the formed structures reveals pronounced opalescence, which confirms that their structure corresponds to the photonic-crystal superlattice.
CONCLUSIONS
The laboratory complex for production of colloidal photonic-crystalline structures, firstly, makes it possible to produce high-quality samples with reproducible properties, secondly, it provides an opportunity to carry out research into the process of nanostructure formation at a modern and methodologically competent level, thirdly, it is a source of materials for improving the methodological and metrological bases of research, fourthly, it is used in the educational process to develop and consolidate practical skills and competences in the field of nanostructures, fourthly, it is used in the educational process to develop and consolidate practical skills and competences in the field of nanostructures.
The elaboration of theoretical, hardware and software base in the development of the complex can serve as a basis for the design of real production taking into account the main aspects and key influencing factors. Each part of the complex can be scaled up to ensure the required productivity of production of products based on colloidal photonic-crystalline films.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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