A method for producing crystalline α-Fe2O3 nanoparticles involving ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The method involves preparing an aqueous extract from the seeds of a plant in the family Linacae and dropwise addition of the extract to the solution of an iron (III)-containing precursor. The method yields crystalline nanoparticles of α-Fe.sub.2O.sub.3 having a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 250 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. A method for the photocatalytic decomposition of organic pollutants using the nanoparticles is disclosed. An antibacterial composition containing the crystalline α-Fe.sub.2O.sub.3 nanoparticles is also disclosed.

A method for producing crystalline α-Fe2O3 nanoparticles involving ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The method involves preparing an aqueous extract from the seeds of a plant in the family Linaceae and dropwise addition of the extract to the solution of an iron (III)-containing precursor. The method yields crystalline nanoparticles of α-Fe.sub.2O.sub.3 having a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 250 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. A method for the photocatalytic decomposition of organic pollutants using the nanoparticles is disclosed. An antibacterial composition containing the crystalline α-Fe.sub.2O.sub.3 nanoparticles is also disclosed.

A method for producing crystalline α-Fe2O3 nanoparticles involving ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The method involves preparing an aqueous extract from the seeds of a plant in the family Linaceae and dropwise addition of the extract to the solution of an iron (III)-containing precursor. The method yields crystalline nanoparticles of α-Fe.sub.2O.sub.3 having a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 250 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. A method for the photocatalytic decomposition of organic pollutants using the nanoparticles is disclosed. An antibacterial composition containing the crystalline α-Fe.sub.2O.sub.3 nanoparticles is also disclosed.

An apparatus for physical vapor transport growth of semiconductor crystals having a cylindrical vacuum enclosure defining an axis of symmetry; a reaction-cell support for supporting a reaction cell inside the vacuum enclosure; a cylindrical reaction cell made of material that is transparent to RF energy and having a height Hcell defined along the axis of symmetry; an RF coil provided around exterior of the vacuum enclosure and axially centered about the axis of symmetry, wherein the RF coil is configured to generate a uniform RF field along at least the height Hcell; and, an insulation configured for generating thermal gradient inside the reaction cell along the axis of symmetry. The ratio of height of the RF induction coil, measured along the axis of symmetry, to the height Hcell may range from 2.5 to 4.0 or from 2.8 to 4.0.

An apparatus for physical vapor transport growth of semiconductor crystals having a cylindrical vacuum enclosure defining an axis of symmetry; a reaction-cell support for supporting a reaction cell inside the vacuum enclosure; a cylindrical reaction cell made of material that is transparent to RF energy and having a height Hcell defined along the axis of symmetry; an RF coil provided around exterior of the vacuum enclosure and axially centered about the axis of symmetry, wherein the RF coil is configured to generate a uniform RF field along at least the height Hcell; and, an insulation configured for generating thermal gradient inside the reaction cell along the axis of symmetry. The ratio of height of the RF induction coil, measured along the axis of symmetry, to the height Hcell may range from 2.5 to 4.0 or from 2.8 to 4.0.

In an embodiment, a system includes a three-dimensional (3D) printer, a neutral feedstock, a p-doped feedstock, an n-doped feedstock, and a laser. The 3D printer includes a platen and an enclosure. The platen includes an inert metal. The enclosure includes an inert atmosphere. The neutral feedstock is configured to be deposited onto the platen. The neutral feedstock includes a halogenated solution and a nanoparticle having a negative electron affinity. The p-doped feedstock is configured to be deposited onto the platen. The p-doped feedstock includes a boronated compound introduced to the neutral feedstock. The n-doped feedstock is configured to be deposited onto the platen. The n-doped feedstock includes a phosphorous compound introduced to the neutral feedstock. The laser is configured to induce the nanoparticle to emit solvated electrons into the halogenated solution to form, by reduction, layers of a ceramic comprising a neutral layer, a p-doped layer, and an n-doped layer.

A method for producing crystalline -Fe2O3 nanoparticles involving ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The method involves preparing an aqueous extract from the seeds of a plant in the family Linacae and dropwise addition of the extract to the solution of an iron (III)-containing precursor. The method yields crystalline nanoparticles of -Fe.sub.2O.sub.3 having a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 250 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. A method for the photocatalytic decomposition of organic pollutants using the nanoparticles is disclosed. An antibacterial composition containing the crystalline -Fe.sub.2O.sub.3 nanoparticles is also disclosed.

A method for producing crystalline -Fe2O3 nanoparticles involving ultrasonic treatment of a solution of an iron (III)-containing precursor and an extract from the seeds of a plant in the family Linaceae. The method involves preparing an aqueous extract from the seeds of a plant in the family Linacae and dropwise addition of the extract to the solution of an iron (III)-containing precursor. The method yields crystalline nanoparticles of -Fe.sub.2O.sub.3 having a spherical morphology with a diameter of 100 nm to 300 nm, a mean surface area of 240 to 250 m.sup.2/g, and a type-II nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. A method for the photocatalytic decomposition of organic pollutants using the nanoparticles is disclosed. An antibacterial composition containing the crystalline -Fe.sub.2O.sub.3 nanoparticles is also disclosed.

In an embodiment, a system includes a three-dimensional (3D) printer, a neutral feedstock, a p-doped feedstock, an n-doped feedstock, and a laser. The 3D printer includes a platen and an enclosure. The platen includes an inert metal. The enclosure includes an inert atmosphere. The neutral feedstock is configured to be deposited onto the platen. The neutral feedstock includes a halogenated solution and a nanoparticle having a negative electron affinity. The p-doped feedstock is configured to be deposited onto the platen. The p-doped feedstock includes a boronated compound introduced to the neutral feedstock. The n-doped feedstock is configured to be deposited onto the platen. The n-doped feedstock includes a phosphorous compound introduced to the neutral feedstock. The laser is configured to induce the nanoparticle to emit solvated electrons into the halogenated solution to form, by reduction, layers of a ceramic comprising a neutral layer, a p-doped layer, and an n-doped layer.

In general, the systems and methods described in this application relate to laser-induced nucleation in continuous flow. A method of laser-induced nucleation in continuous flow includes injecting a saturated solution, undersaturated solution, or supersaturated solution through an inlet of a device. The method can include converting the saturated solution or undersaturated solution into supersaturated solution by changing a temperature of the saturated solution or undersaturated solution. The method can include passing one or more laser pulses through the supersaturated solution within the device. The method can include flowing the saturated solution, undersaturated solution, or the supersaturated solution through an outlet of the device.